Entity Framework Video Content

8/10/2019 Entity Framework Video Content

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Part 1 - What is Entity Framework

What is Entity Framework

Entity Framework is an ORM framework. ORM stands for Object Relational Mapping.

What is Object Relational Mapping framework

Object Relational Mapping framework automatically creates classes based on database tables, and

the vice versa is also true, that is, it can also automatically generate necessary SQL to create

database tables based on classes.

Let's understand what entity framework can provide with an example. Assume we have the

following 2 tables

We want to display the above data from both the tables in a webform as shown below.

To achieve this

1. We need to create Department and Employee classes

2. Write ADO.NET code to retrieve data from the database3. Once the data is retrieved we need to create Department and Employee objects and populate


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them with data.

Entity Framework can do all of the above automatically, if we provide it with the database

schema.

Installing NuGet Package Manager

1. From Visual Studio 2010 Tools menu, select Extension Manager

2. Click on Online Gallery in the Extension Manager window

3. Search for NuGet

4. Finally Download NuGet Package Manager and install

Please note:You must restart visual studio for the changes to take effect.

Step 1: Create a new "Empty ASP.NET Web Application" with name=Demo.

Step 2: Installing Entity Framework

a)Click on Tools - NuGet Package Manager - Manage NuGet Packages for solution

b)Click on "Online" tab in "Manage NuGet Packages" window

c)Type "EntityFramework" in the search textbox on the top right hand corner

d)Finally click on the "Install" button.


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At this point Entity Framework version 6.1is installed and a reference to EntityFrameworkassembly is also automatically added.

Step 3:Create "Departments" and "Employees" tables.

CreatetableDepartments

(

ID intprimarykeyidentity,

Name nvarchar(50),

Location nvarchar(50))

CreatetableEmployees

(


FirstName nvarchar(50),

LastName nvarchar(50),

Gender nvarchar(50),

Salary int,

DepartmentId intforeignkeyreferencesDepartments(Id))


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Step 4:Populate the tables created in Step 3, with data

InsertintoDepartments values ('IT', 'New York')

InsertintoDepartments values ('HR', 'London')

InsertintoDepartments values ('Payroll', 'Sydney')

InsertintoEmployees values ('Mark', 'Hastings', 'Male', 60000, 1)

InsertintoEmployees values ('Steve', 'Pound', 'Male', 45000, 3)

InsertintoEmployees values ('Ben', 'Hoskins', 'Male', 70000, 1)

InsertintoEmployees values ('Philip', 'Hastings', 'Male', 45000, 2)

InsertintoEmployees values ('Mary', 'Lambeth', 'Female', 30000, 2)

InsertintoEmployees values ('Valarie', 'Vikings', 'Female', 35000, 3)

InsertintoEmployees values ('John', 'Stanmore', 'Male', 80000, 1)

Step 5:Right click on the project in solution explorer and add ADO.NET Entity Data Model.

Change the name from Model1.edmxto EmployeeModel.edmx

Step 6:Select "Generate from database"and click "Next"

Step 7:Choose Your Data Connection

a)Click on "New Connection" button

b)Select "Microsoft SQL Server" as Data source, and ".Net Framework Data Provider for SQL

Server" option from "Data provider" dropdownlist. Click Continue.

c)On "Connection Properties" screen, specify SQL Server Name. If you are using local installationof SQL Server then use (local) or . in the "server name" dropdownlist.


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d)Specify the Authentication you want to use.

e)Select the database from "Select or enter database name" dropdownlist.

f)Finally "Test connection" and click "OK"

g)At this point we should be back on "Choose Your Data Connection" window. Make sure "Save

entity connection settings in Web.Config as" checkbox is selected and change the name of theconnection string to "EmployeeDBContext" and then Click "Next"

Step 8:On "Choose Your Database Objects" screen, select "Departments" and "Employees"

tables. Change the Model Namespace to "EmployeeModel" and click "Finish". At this point you

should have EmployeeModel.edmx created.

EmployeeModel.Designer.csfile is also generated. This file contains Employee and Departmentclasses. Tables are mapped to classes and columns are mapped to class properties.

Step 9: Add a webform. Drag and drop a GridView and an EntityDataSource control on the

webform.

Step 10:Build the solution. Flip the WebForm1.aspx to design mode.

a)Right click on EntityDataSource control and select "Show smart tag" option from the context

menu.

b)Click on "Configure Data Source" link

c)Select "Named Connection" radiobutton and select "EmployeeDBContext" from the

dropdownlist.

d)Select "EmployeeDBContext" option from "DefaultContainerName" dropdownlist and click

"Next"

e)On "Configure Data Selection" screen, select "Departments" from "EntitySetName"

dropdownlist and click "Finish"

f)Right click on "GridView1" control and select "Show smart tag" option.

g)Click on "Auto Format" link and select "Colorful" option from "AutoFormat" window and click

"OK".


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h)Select "EntityDataSource1" from "Choose Data Source" dropdownlist.

I)Click on "Eidt Columns" link and add a "Template Field". Set HeaderText=Employees and click

OK.

j)Now click "Edit Templates" link.

k)Drag and drop a GridView controll)Select "Edit DataBindings" link

m)Select "Custom binding" radiobutton and type Eval("Employees") in "Code expression"

textbox and click OK.

n)Select "End Template Editing" option from "GridView1" smart tasks pane.

Step 11: Right click on "EntityDataSource1" control and select "Properties". In properties window

set Include=Employees

Run the web application and notice that Departments and Employees are displayed as expected.We have achieved all this without writing a single line of code.

In this demo, we have used schema first approach of entity framework. We can also use Model

First or Code First approaches. We will discuss these in our subsequent videos.

Part 2 - Entity Framework Model First Approach

Suggested Videos


In this video we will discuss using Model First Approach of Entity Framework. This is continuation

toPart 1.Please watchPart 1before proceeding.

Entity Framework supports the following three approaches

1.Schema First Approach - Discussed inPart 12.Model First Approach - In this video.
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3.Code First Approach - Next Video

In the Model First Approach, We first create the Entity Model. That is we create

1.Entities

2.Relationships Between Entities

3.Inheritance hierarchies etc.

We do all this directly on the design surface of the EDMX file. We will be continuing with the

same example that we started inPart 1ofEntity Framework Tutorial.

Step 1:First delete the "EmployeeModel.edmx" file from the existing solution

Step 2:Add a new "ADO.NET Entity Data Model" file with name = EmployeeModel.

Step 3: On "Choose Model Contents" screen, select "Empty Model" and click "Finish"

Step 4:At this point, we have a blank EmployeeModel.edmx file added to the solution. Now, right

click on the designer surface and then select : Add - Entity. Set,

Entity Name = Department

Base Type = None

Entity Set = Departments

Create Key property = Select the check box

Property Name = Id

Property Type = Int32

Finally click OK.
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Step 5:Right click on "Department" entity and select "Add - Scalar Property". Change the

property name to "Name". Right click on the "Name" property that we just added and select

"properties" from the context menu. Notice that the "Type" of "Name" property is set to

"String".

Step 6: Similarly add "Location" property for the "Department" entity. At this point, the

"Department" entity should look as shown below.

Step 7:Add "Employee" entity and the following scalar properties.

FirstName (Type = string)

LastName (Type = string)


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Gender (Type = string)

Salary (Type = int)

Step 8: At this point, Department and Employee entities should look as shown below.

Step 9:We need to add "Employees" navigation property for the "Department" entity, and

"Department" navigation property for the "Employee" entity. To do this, right click on

the design surface and select "Add - Association". In the "Add Association" window, set values as

shown in the image below and click "OK"


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Step 10:At this point, we should have the following created.

a)Employees navigation property in the Department entity

b)Department navigation property in the Employee entity

c)DepartmentId scalar property

Step 11:Right click on the design surface, and select "Genedrate Database from Model..." option

Step 12: On "Choose Your Data Connection"screen, click "Next"

Step 13: At this point, we should have the required SQL generated to create

a)Departments table

b)Employees table

c)Primary key constraints for Departments and Employees tablesd)Foreign key constraint

e)Indexes

Step 14: Click Finish. Now, we should have "EmployeeModel.edmx.sql" file generated with the

required SQL. If you already have "Departments" and "Employees" tables in the database, delete

them. Right click on the file and select "Execute SQL" option from the context menu.

Step 15: Populate the "Departments" and "Employees" tables with sample data using the script

below.

InsertintoDepartments values ('IT', 'New York')InsertintoDepartments values ('HR', 'London')







InsertintoEmployees values ('Valarie', 'Vikings', 'Female', 35000, 3)

InsertintoEmployees values ('John', 'Stanmore', 'Male', 80000, 1)


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Step 16:Run the application by pressing CTRL + F5. We will get the following runtime error.

The specified default EntityContainer name 'EmployeeDBContext' could not be found in the

mapping and metadata information.

Parameter name: defaultContainerName

Step 17:Open WebForm1.aspx in source mode, and set ConnectionString and

DefaultContainerName properties of EntityDataSource control as shown below.

At this point we should get the output we expect.

Part 3 - Entity Framework Code First Approach

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Entity Framework supports

1.Database first or schema first approach -Discussed in Part 12.Model first appraoch -Discussed in Part 2

3.Code first approach - In this video

Code-first approach allows us to create our custom classes first and based on those custom

classes entity framework can generate database automatically for us.Let's understand this with

an example. We will be modifying the example we worked with inPart 2.

Step 1:Delete EmployeeModel.edmx && EmployeeModel.edmx.sql files from the solution

explorer.

Step 2: Add a class file to the project. Name it Employee.cs. Copy and paste the following code.

publicclassEmployee

{

// Scalar Properties

publicintId{ get; set; }

publicstringFirstName{ get; set; }

publicstringLastName{ get; set; }

publicstringGender{ get; set; }

publicintSalary{ get; set; }

// Navigation Property
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publicDepartmentDepartment{ get; set; }

}

Step 3: Add a class file to the project. Name it Department.cs. Copy and paste the following code.

publicclassDepartment

{

// Scalar Properties


publicstringName{ get; set; }

publicstringLocation{ get; set; }

// Navigation Property

publicListEmployees{ get; set; }

}

Step 4:Add a class file to the project. Name it EmployeeDBContext.cs. Copy and paste thefollowing code.

// EmployeeDBContext class must inherit from DbContext

// present in System.Data.Entity namespace

publicclassEmployeeDBContext: DbContext

{

publicDbSetDepartments{ get; set; }

publicDbSetEmployees{ get; set; }

}

Step 5:Add a class file to the project. Name it EmployeeRepository.cs . Copy and paste thefollowing code.

publicclassEmployeeRepository

{

publicListGetDepartments()

{

EmployeeDBContextemployeeDBContext=newEmployeeDBContext();

returnemployeeDBContext.Departments.Include("Employees").ToList();

}

}

Step 6:Add the database connection string in web.config file.

Please Note:If ProviderName is not specified the following runtime error will be thrown.

The connection string 'EmployeeDBContext' in the application's configuration file does not contain

the required providerName attribute."


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Step 7:Configure Object Data Source control

a)Delete EntityDataSource control, that is already there in WebForm1.aspx.

b)Drag and Drop ObjectDataSource control.

c)Right click on ObjectDataSource control and select "Show Smart Tag" option from the context

menu

d)Click on "Configure Data Source..." link

e)On "Choose a Business Object" screen, select "EmployeeRepository" and click "Next"

f)On "Define Data Methods" screen, select GetDepartments() method and click "Finish"

Step 8: Configure GridView control

a)Right click on GridView control and select "Show Smart Tag" option from the context menu

b)Select "ObjectDataSource1" from "Choose Data Source" dropdownlist

c)Click "No" to "Refresh Fields and Keys for GridView1" when prompted

Step 9: Rebuild the solution.

Step 10: Delete the already existing database from SQL Server Management Studio.

Step 11: Run the application by pressing CTRL + F5. Notice that we don't have any data displayed

on WebForm1. This is because we don't have any data in the Departments and Employees tables.

At this point We have the following created automatically.

a)Sample database

b)Departments table

c)Employees table

Step 12: Use the SQL script to populate the tables with data.InsertintoDepartments values ('IT', 'New York')








InsertintoEmployees values ('Valarie', 'Vikings', 'Female', 35000, 3)InsertintoEmployees values ('John', 'Stanmore', 'Male', 80000, 1)

Step 13 :Refresh the Web Form and we should see the data we expect.


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Part 4 - Customizing table, column and foreign key column names when using entity

framework code first approach

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In this vide we will discuss, customizing table, column and foreign key column names when using

entity framework code first approach. This is continuation toPart 3.Please watchPart 3before

proceeding.

InPart 3,we have discussed generating Departments and Employees tables using Entity

Framework Code first approach.

Entity Framework generated the following Employees table. Notice the column names.

Department_Idcolumn has an underscore in it's name. Let's say we want the column to be

generated as DepartmenId(without an underscore)

Entity Framework generated the above Employees table based on the following custom Employee

class that we created.

publicclassEmployee

{







}

To achieve this use the ForeignKey attribute present in

System.ComponentModel.DataAnnotations.Schemanamespace. Modify the Employee class as

shown below.

publicclassEmployee

{



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publicintDepartmentId{ get; set; }

[ForeignKey("DepartmentId")]


}

Rebuild the solution, and run the application.

You will get the following error. We will discuss the reasons for this error and how to fix it the

right way in a later video session.

The model backing the 'EmployeeDBContext' context has changed since the database was

created. Consider using Code First Migrations to update the database

(http://go.microsoft.com/fwlink/?LinkId=238269).

For now to get around the error, delete the Sample database using SQL Server ManagementStudio, and then try to run the application again. A blank webform will be displayed. Now check

the Employees tables using SQL Server Management Studio and notice that the DepartmentId

column is created without an underscore as expected.

To customize the table name, use Table attribute and to customize column name use Column

attribute.

For example, to change

Table name from Employees to tblEmployees and

FirstName column to First_Name

We would modify the Employee class as shown below.

[Table("tblEmployees")]

publicclassEmployee

{


[Column("First_Name")]






[ForeignKey("DepartmentId")]publicDepartmentDepartment{ get; set; }


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}

Entity Framework would then generate the following. Notice the table name and First_Name

column.

Part 5 - How to handle model changes in entity framework

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Part 4 - Customizing table & column names

In this video we will discuss, how to handle model changes after the database is already created.

This is continuation toPart 4.Please watchPart 4before proceeding.

At the moment the Employee class is as shown below


publicclassEmployee

{










}

The following is the table Entity Framework has generated based on the above Employee class
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Now let us add JobTitle property to the Employee class. The modified Employee class is shown

below.


publicclassEmployee

{


[Column("First_Name")]publicstringFirstName{ get; set; }







publicstringJobTitle{ get; set; }

}

At this point if we run the application, we get the following error.

The model backing the 'EmployeeDBContext' context has changed since the database was

created. Consider using Code First Migrations to update the database

(http://go.microsoft.com/fwlink/?LinkId=238269).

This is because the model (i.e Employee class) has changed since the database was created. This

means the Model and the database are no longer in sync and hence we get the error. To check if

the model has changed since the database was created, entity framework uses

__MigrationHistory table that is auto-generated.

To fix this error, we have to tell entity framework what to do when the model changes.

Add Global.asax file to the web application project. Include the following code in

Application_Start() method. Here, we are telling the entity framework to drop and recreate

database every time the model changes.

Database.SetInitializer(newDropCreateDatabaseIfModelChanges());

Another option is, to drop and recreate the database always. To drop and recreate the database

always we would change the code in Application_Start() method as shown below.

Database.SetInitializer(newDropCreateDatabaseAlways());

Please Note:Database class is present in System.Data.Entity namespace.


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Run the application, and notice that the database is dropped and recreated. But the webform

does not display any data, as there is no data in Departments and tblEmployees tables. For now

let's manually populate the tables using the followng SQL script.

InsertintoDepartments values ('IT', 'New York')



InsertintotblEmployees values ('Mark', 'Hastings', 'Male', 60000, 1, 'Developer')

InsertintotblEmployees values ('Steve', 'Pound', 'Male', 45000, 3, 'Manager')

InsertintotblEmployees values ('Ben', 'Hoskins', 'Male', 70000, 1, 'Developer')

InsertintotblEmployees values ('Philip', 'Hastings', 'Male', 45000, 2, 'Recruiter')

InsertintotblEmployees values ('Mary', 'Lambeth', 'Female', 30000, 2, 'Recruiter')

InsertintotblEmployees values ('Valarie', 'Vikings', 'Female', 35000, 3, 'Manager')

InsertintotblEmployees values ('John', 'Stanmore', 'Male', 80000, 1, 'Developer')

Referesh the webform. Notice that JobTitle is not displayed on the WebForm. To fix this add a

boundfield to the GridView control that displays Employees details as shown below.

Part 6 - How to seed database with test data using entity framework

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So far in this video series, we have been manually populating the database with test data using

the insert sql script. Entity Framework can automate this. We will be working with the example we

worked with inPart 5.Here are the steps.

Step 1:Right click on the project in solution explorer and add a class file with name =

EmployeeDBContextSeeder.cs

Step 2: Copy and paste the following code in EmployeeDBContextSeeder.cs file

usingSystem.Collections.Generic;usingSystem.Data.Entity;
http://csharp-video-tutorials.blogspot.com/2014/05/part-3-entity-framework-code-first_6.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-3-entity-framework-code-first_6.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-4-customizing-table-column-and.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-4-customizing-table-column-and.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-4-customizing-table-column-and.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-3-entity-framework-code-first_6.html


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namespaceEntityFrameworkDemo

{

publicclassEmployeeDBContextSeeder:

DropCreateDatabaseIfModelChanges

{

protectedoverridevoidSeed(EmployeeDBContextcontext)

{

Departmentdepartment1=newDepartment()

{

Name="IT",

Location="New York",

Employees=newList()

{

newEmployee()

{

FirstName="Mark",LastName="Hastings",

Gender="Male",

Salary=60000,

JobTitle="Developer"

},

newEmployee()

{

FirstName="Ben",

LastName="Hoskins",

Gender="Male",Salary=70000,

JobTitle="Sr. Developer"

},

newEmployee()

{

FirstName="John",

LastName="Stanmore",

Gender="Male",

Salary=80000,

JobTitle="Project Manager"}

}

};


{

Name="HR",

Location="London",

Employees=newList()

{newEmployee()


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{

FirstName="Philip",

LastName="Hastings",

Gender="Male",

Salary=45000,

JobTitle="Recruiter"

},

newEmployee()

{

FirstName="Mary",

LastName="Lambeth",

Gender="Female",

Salary=30000,

JobTitle="Sr. Recruiter"

}

}};


{

Name="Payroll",

Location="Sydney",

Employees=newList()

{

newEmployee()

{

FirstName="Steve",LastName="Pound",

Gender="Male",

Salary=45000,

JobTitle="Sr. Payroll Admin",

},

newEmployee()

{

FirstName="Valarie",

LastName="Vikings",

Gender="Female",Salary=35000,

JobTitle="Payroll Admin",

}

}

};

context.Departments.Add(department1);



base.Seed(context);


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}

}

}

Step 3:Copy and paste the following line in Application_Start() method Global.asax file

Database.SetInitializer(newEmployeeDBContextSeeder());

Step 4:Remove the following Table and Column attributes from Employee.cs file.



At this point Employee class should look as shown below

publicclassEmployee

{


publicstringFirstName{ get; set; }publicstringLastName{ get; set; }






publicstringJobTitle{ get; set; }

}

Step 5:Run the application and notice that the Sample database, Departments and Employeestables are created and populated with test data automatically.

Part 7 - Using stored procedures with entity framework

Suggested Videos




In this video we will discuss using our own custom stored procedures to perform Insert, Update

and Delete operations using entity framework. We will be using the following Employees table

for this demo.
http://csharp-video-tutorials.blogspot.com/2014/05/part-4-customizing-table-column-and.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-4-customizing-table-column-and.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-6-how-to-seed-database-with-test.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-6-how-to-seed-database-with-test.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-6-how-to-seed-database-with-test.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-4-customizing-table-column-and.html


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Step 1:Use the following SQL Script to create and populate Employee table.


(


Name nvarchar(50),

Gender nvarchar(50),Salary int

)

InsertintoEmployees values ('Mark', 'Male', 60000)

InsertintoEmployees values ('Steve', 'Male', 45000)

InsertintoEmployees values ('Ben', 'Male', 70000)

InsertintoEmployees values ('Philip', 'Male', 45000)

InsertintoEmployees values ('Mary', 'Female', 30000)

InsertintoEmployees values ('Valarie', 'Female', 35000)

InsertintoEmployees values ('John', 'Male', 80000)

Step 2:Create Insert, Update and Delete stored procedures

CreateprocedureInsertEmployee

@Name nvarchar(50),

@Gender nvarchar(50),

@Salary int

as

Begin

InsertintoEmployees values (@Name, @Gender, @Salary)

End

Go

CreateprocedureUpdateEmployee

@ID int,

@Name nvarchar(50),

@Gender nvarchar(50),

@Salary int

as

Begin

UpdateEmployees SetName = @Name, Gender = @Gender,

Salary = @Salary


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whereID = @ID

End

Go

CreateprocedureDeleteEmployee

@ID int

as

Begin

DeletefromEmployees whereID = @ID

End

Go

Step 3:Create a new empty asp.net web application

Step 4: Add a new ADO.NET Entity Data Model.

a)On Choose Model Contentsscreen select "Generate from database"option and click Next

b)On "Choose Your Data Connections" screen give a meaningful name for the connection string

that will be stored in the web.config file. I have named it EmployeeDBContext. Click Next.

c)On "Choose Your Database Objects" screen, select Employees Table and the 3 storedprocedures (InsertEmployee, UpdateEmployee, DeleteEmployee). Provide a meaningful name for

the Model namespace. I have named it EmployeeModel. CLick Finish.


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At this point on the ADO.NET Entity Model designer surface, we should be able to see the

Employee entity but not the stored procedures.

To view the stored procedures,

1.Right click on entity model designer surface and select "Model Broswer" from the context

menu.

2.Expand Stored Procedures folder

Step 5:Add a web form to the project. Drag and drop the following 3 controls and build thesolution.


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1.GridView

2.DetailsView

3.EntityDataSource

Step 6: Configure EntityDataSource control

a). Right click on EntityDataSource control and select "Show Smart Tag" option

b)Click on Configure Data Source link

c)Select EmployeeDBContext from the Named Connection dropdownlist and click Next

d)Select the options on "Configure Data Selection" screen as shown in the image below and click

Finish

Step 7:Configure GridView control

a). Right click on GridView control and select "Show Smart Tag" option

b)Click on "Auto Format" link and select "Colourful" scheme

c)Select "EntityDataSource1" from "Choose Data Source" dropdownlist


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d)Select Enable Editing and Enable Deleting checkboxes

Step 8:Configure DetailsView control

a)Right click on DetailsView control and select "Show Smart Tag" option



d)Select Enable Inserting checkbox

e)Set DeafultMode=Insert. Use properties window to set this.

f)Set InsertVisible="false" for the ID BoundField. You can do this directly in the HTML Source.g)Generate ItemInserted event handler method for DetailsView control. Copy and paste the

following code.

protectedvoidDetailsView1_ItemInserted (objectsender, DetailsViewInsertedEventArgse)

{

GridView1.DataBind();

}

At this point if you run the application, and if you insert, update and delete employees, by default

entity framework will use the sql it auto-generates and not our custom stored procedures.

To tell the entity framework to use the stored procedures, we have to map them to the Employee

entity.

Here are the steps.

1.Right click on "Employee" entity on "EmployeeModel.edmx" and select "Stored Procedure

Mapping" option from the context menu.

2.In the "Mapping Details" windows specify the Insert, Update and Delete stored procedures

that you want to use with "Employee" entity


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At this point,

1.Run SQL Profiler

2.Run the application

3.Insert, Update and Delete Employee, and notice that the respective stored procedures are

being called now.

Part 8 - Using stored procedures with entity framework code first approach

Suggested Videos




In this video we will discuss using stored procedures to perform Insert, Update and Deleteoperations using entity framework code first approach.

Step 1:Create a new empty asp.net web application project. Name it Demo. Install entity

framework if it's not already installed.

Step 2:Add a class file to the project. Name it Employee.cs. Copy and paste the following code.

namespaceDemo

{

publicclassEmployee

{ publicintID { get; set; }
http://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-6-how-to-seed-database-with-test.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-6-how-to-seed-database-with-test.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-7-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-7-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-7-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-6-how-to-seed-database-with-test.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-5-how-to-handle-model-changes-in.html


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publicstringName { get; set; }

publicstringGender { get; set; }

publicintSalary { get; set; }

}

}

Step 3:Add a class file to the project. Name it EmployeeDBContext.cs. Copy and paste the

following code.

usingSystem.Data.Entity;

namespaceDemo

{


{

publicDbSet Employees { get; set; }

protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder){

// This line will tell entity framework to use stored procedures

// when inserting, updating and deleting Employees

modelBuilder.Entity().MapToStoredProcedures();

base.OnModelCreating(modelBuilder);

}

}

}

Step 4:Add a class file to the project. Name it EmployeeRepository.cs . Copy and paste thefollowing code.

usingSystem.Collections.Generic;

usingSystem.Linq;

namespaceDemo

{

publicclassEmployeeRepository

{

EmployeeDBContextemployeeDBContext = newEmployeeDBContext();

publicList GetEmployees(){

returnemployeeDBContext.Employees.ToList();

}

publicvoidInsertEmployee(Employeeemployee)

{

employeeDBContext.Employees.Add(employee);

employeeDBContext.SaveChanges();

}

publicvoidUpdateEmployee(Employeeemployee)


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{

EmployeeemployeeToUpdate = employeeDBContext

.Employees.SingleOrDefault(x => x.ID == employee.ID);

employeeToUpdate.Name = employee.Name;

employeeToUpdate.Gender = employee.Gender;

employeeToUpdate.Salary = employee.Salary;


}

publicvoidDeleteEmployee(Employeeemployee)

{

EmployeeemployeeToDelete = employeeDBContext

.Employees.SingleOrDefault(x => x.ID == employee.ID);

employeeDBContext.Employees.Remove(employeeToDelete);


}}

}


Step 6:Add a webform to the project. Drag and drop the following 3 controls and build the

solution.

1.GridView

2.DetailsView

3.ObjectDataSource

Step 7:Configure ObjectDataSource control

a). Right click on ObjectDataSource control and select "Show Smart Tag" option


c)Select Demo.EmployeeRepository on Choose a Business Object screen and click Nextd)On Define Data Methods screen

i)On SELECT tab - Select GetEmployees() method

ii)On UPDATE tab - Select UpdateEmployees(Employee employee) method

iii)On INSERT tab - Select InsertEmployees(Employee employee) method

iv)On DELETE tab - Select DeletEmployees(Employee employee) method




c)Select "ObjectDataSource1" from "Choose Data Source" dropdownlistd)Select Enable Editing and Enable Deleting checkboxes


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e)Set DataKeyNames="ID". Do this in the properties window of the GridView control

Step 9: Configure DetailsView control


b)Click on "Auto Format"link and select "Colourful" scheme

c)Select "ObjectDataSource1" from "Choose Data Source" dropdownlist



f)Set InsertVisible="false" for the ID BoundField. You can do this directly in the HTML Source.

Step 10:If you already have Sample database in SQL Server. Delete it from SQL Server

Management Studio.

Step 11: Run the application by pressing CTRL + F5. Notice that we don't have any data displayed

on WebForm1. This is because we don't have any data in the Employees table.

At this point we have the Sample database and Employees table created automatically. The

following stored procedures are also automatically created.

Employee_Delete

Employee_Insert

Employee_Update

By default, the following should be the naming convention for the stored procedures.

INSERT stored procedure - [Entity_Name]_Insert. Insert Stored procedure should return the auto-

generated identity column value.

UPDATE stored procedure- [Entity_Name]_UpdateDELETE stored procedure- [Entity_Name]_Delete

Step 12:Use the below SQL script to populate Employees tables with test data.

InsertintoEmployees values ('Mark', 'Male', 60000)

InsertintoEmployees values ('Steve', 'Male', 45000)

InsertintoEmployees values ('Ben', 'Male', 70000)

InsertintoEmployees values ('Philip', 'Male', 45000)

InsertintoEmployees values ('Mary', 'Female', 30000)

InsertintoEmployees values ('Valarie', 'Female', 35000)

InsertintoEmployees values ('John', 'Male', 80000)

At this point,

1.Run SQL Prrofiler

2.Run the application

3.Insert, Update and Delete Employees, and notice that the respective stored procedures are

being called as expected.


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Part 9 - Overriding stored procedure defaults with entity framework code first

approach

Suggested Videos



Part 8 - Using stored procedures with entity frameowrk code first approach

In this video we will discuss, changing the default Insert, Update and Delete stored procedure

names that are auto-generated by entity framework code first approach. This is continuation to

Part 8.Please watchPart 8before proceeding.


{


protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder)

{

modelBuilder.Entity().MapToStoredProcedures();


}

}

By default, the code above generates the following 3 stored procedures for Inserting, Updating

and Deleting Employee objects.Employee_Insert

Employee_Update

Employee_Delete

If you want to override or change the default names of auto-generated stored procedures, change

the code in EmployeeDBContext class as shown below.


{



{

modelBuilder.Entity()

.MapToStoredProcedures(p => p.Insert(x => x.HasName("InsertEmployee")));


.MapToStoredProcedures(p => p.Update(x => x.HasName("UpdateEmployee")));


.MapToStoredProcedures(p => p.Delete(x => x.HasName("DeleteEmployee")));

base.OnModelCreating(modelBuilder);}
http://csharp-video-tutorials.blogspot.com/2014/05/part-6-how-to-seed-database-with-test.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-6-how-to-seed-database-with-test.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-7-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-7-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-7-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-6-how-to-seed-database-with-test.html


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}

At this point delete the Sample database and run WebForm1 again. Notice that the generated

stored procedures now have the names we specified.

The above code can also be rewritten as shown below


{



{

modelBuilder.Entity().MapToStoredProcedures

(p => p.Insert(i => i.HasName("InsertEmployee"))

.Update(u => u.HasName("UpdateEmployee"))

.Delete(d => d.HasName("DeleteEmployee"))

);


}

}

The default parameter names of the stored procedures can also be changed using the following

code.


{



{

modelBuilder.Entity().MapToStoredProcedures

(p => p.Insert(i => i.HasName("InsertEmployee")

.Parameter(n => n.Name, "EmployeeName")

.Parameter(n => n.Gender, "EmployeeGender")

.Parameter(n => n.Salary, "EmployeeSalary"))

.Update(u => u.HasName("UpdateEmployee")

.Parameter(n => n.ID, "EmployeeID")

.Parameter(n => n.Name, "EmployeeName")

.Parameter(n => n.Gender, "EmployeeGender")

.Parameter(n => n.Salary, "EmployeeSalary"))

.Delete(d => d.HasName("DeleteEmployee")

.Parameter(n => n.ID, "EmployeeID")));


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}

}

At this point drop the Sample database and run WebForm1 again. Notice that the stored

procedure parameters have the names we specified.

Part 10 - Entity splitting in entity framework

Suggested Videos



Part 9 - Overriding stored procedure defaults with entity frameowrk code first approach

Entity splitting refers to mapping an entity to two or more tables when the tables share a

common key. Let us understand Entity splitting with an example.

We have the following 2 tables. Notice that both the table share the common key - EmployeeID.

Employees Table
http://csharp-video-tutorials.blogspot.com/2014/05/part-7-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-7-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-9-overriding-stored-procedure.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-9-overriding-stored-procedure.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-9-overriding-stored-procedure.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-7-using-stored-procedures-with.html


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EmployeeContactDetails Table

SQL Script to create the database objects and populate them with test data


(

EmployeeID intprimarykeyidentity,



Gender nvarchar(50))

GO

CreatetableEmployeeContactDetails

(

EmployeeID intprimarykey,

Email nvarchar(50),

Mobile nvarchar(50),

LandLine nvarchar(50)

)

GO

InsertintoEmployees values ('Mark', 'Hastings', 'Male')

InsertintoEmployees values ('Steve', 'Pound', 'Male')

InsertintoEmployees values ('Ben', 'Hoskins', 'Male')

InsertintoEmployees values ('Philip', 'Hastings', 'Male')

InsertintoEmployees values ('Mary', 'Lambeth', 'Female')

InsertintoEmployeeContactDetails values

(1, '[email protected]', '111111111', '111111111')


(2, '[email protected]', '2222222222', '2222222222')


(3, '[email protected]', '3333333333', '3333333333')


(4, '[email protected]', '44444444444', '44444444444')


(5, '[email protected]', '5555555555', '5555555555')

Now, when we use ADO.NET Entity Framework to generate entities from the database using

database first approach, by default 2 entities will be created, i.e Empoyee andEmployeeContactDetail entities.


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There is a one to one mapping between tables and entities. We want a single Employee to map to

both Employees &EmployeeContactDetailstable.

To achieve this

1.Cut Email, Mobile and LandLine properties from EmployeeContactDetail entity and paste them

in Employeeentity

2.Delete EmployeeContactDetail entity. On "Delete Unmapped Tables and Views" window click

NO.

3.Right click on Employee entity and select "Table Mapping" option from the context menu. Map

EmployeeId, Email, Mobile and LandLine properties to the respective columns of

EmployeeContactDetails table.

At this point we have only one Entity. Build the solution. Add a WebForm. Drag and drop the

following 3 controls.

1.GridView

2.DetailsView

3.EntityDataSource

Configure EntityDataSource controla). Right click on EntityDataSource control and select "Show Smart Tag" option


36/61


c)Select EmployeeDBContext from the Named Connection dropdownlist and click Next

d)Select Employees from EntitySetName dropdownlist and enable Inserts, Updates and Deletes.

Configure GridView control





Configure DetailsView control





e)Set DeafultMode=Insert. Use properties window to set this.f)Set InsertVisible="false" for the EmployeeID BoundField. You can do this directly in the HTML

Source.

g)Generate ItemInserted event handler method for DetailsView control. Copy and paste the

following code.

protectedvoidDetailsView1_ItemInserted(objectsender, DetailsViewInsertedEventArgse)

{


}

At this point run the application. Insert, update and delete an Employee, and notice that both the

tables (Employees and EmployeeContactDetails) are updated as expected.

Part 11 - Entity splitting in entity framework with code first approach

Suggested Videos




Entity splitting refers to mapping an entity to two or more tableswhen the tables share a

common key. We discussed, Entity splitting with database first approach inPart 10.In this video

we will discuss Entity splitting with code first approach.

Step 1:Create a new empty asp.net web application project. Name it Demo. Install entityframework if it's not already installed.
http://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-9-overriding-stored-procedure.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-9-overriding-stored-procedure.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-9-overriding-stored-procedure.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-8-using-stored-procedures-with.html


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Step 2: Add a class file to the project. Name it Employee.cs. Copy and paste the following code.

namespaceDemo

{

publicclassEmployee

{

// These property values should be stored in Employees Table

publicintEmployeeId{ get; set; }




// These property values should be stored in EmployeeContactDetails Table

publicstringEmail{ get; set; }

publicstringMobile{ get; set; }

publicstringLandline{ get; set; }}

}

Step 3: Add a class file to the project. Name it EmployeeDBContext.cs. Copy and paste the

following code.

usingSystem.Data.Entity;

namespaceDemo

{


{publicDbSetEmployees{ get; set; }

}

}

Step 4:Add a class file to the project. Name it EmployeeRepository.cs. Copy and paste the

following code.

usingSystem.Collections.Generic;

usingSystem.Linq;

namespaceDemo

{publicclassEmployeeRepository

{


publicListGetEmployees()

{

returnemployeeDBContext.Employees.ToList();

}

publicvoidInsertEmployee(Employeeemployee){


38/61


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ii) On UPDATE tab - Select UpdateEmployee(Employee employee) method

iii) On INSERT tab - Select InsertEmployee(Employee employee) method

iv) On DELETE tab - Select DeletEmployee(Employee employee) method




c)Select "ObjectDataSource1" from "Choose Data Source" dropdownlist


e)Set DataKeyNames="EmployeeId". Do this in the properties window of the GridView control

f)Set ReadOnly="true" for the EmployeeId BoundField. You can do this directly in the HTML

Source.

Step 9: Configure DetailsView control


b)Click on "Auto Format" link and select "Colourful" schemec)Select "ObjectDataSource1" from "Choose Data Source" dropdownlist



f)Set InsertVisible="false" for the EmployeeId BoundField. You can do this directly in the HTML

Source.

g)Generate ItemInserted event handler method for DetailsView control. Copy and paste the

following code.

protectedvoidDetailsView1_ItemInserted(objectsender, DetailsViewInsertedEventArgse)

{

GridView1.DataBind();}

Step 10: If you already have Sample database in SQL Server. Delete it from SQL Server

Management Studio.

Step 11: Run the application by pressing CTRL + F5. By default entity framework creates one Table

i.e Employees table.But we want entity framework to create the following 2 tables.

a)Employees table with columns EmployeeId, FirstName, LastName and Gender

b)EmployeeContactDetails table with columns EmployeeId, Email, Mobile and Landline

Step 12: Override OnModelCreating() method to tell entity framework to generate 2

tables(Employees& EmployeeContactDetails) for the Employee entity. OnModelCreating()

method is a virtual method present in DbContext class. So, modify EmployeeDBContext class in

EmployeeDBContext.csfile as shown below.


{

publicDbSetEmployees{ get; set; }


{modelBuilder.Entity()


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// Specify properties to map to Employees table

.Map(map=>

{

map.Properties(p=>new

{

p.EmployeeId,

p.FirstName,

p.LastName,

p.Gender

});

map.ToTable("Employees");

})

// Specify properties to map to EmployeeContactDetails table

.Map(map=>

{map.Properties(p=>new

{

p.EmployeeId,

p.Email,

p.Mobile,

p.Landline

});

map.ToTable("EmployeeContactDetails");

});


}

}

Step 13:Delete the Sample database and run the web application.

Step 14: Notice that now we have 2 tablesgenerated by entity framework as expected.


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Step 15:Execute the following SQL script to populate the tables with test data.

InsertintoEmployees values ('Mark', 'Hastings', 'Male')

InsertintoEmployees values ('Steve', 'Pound', 'Male')

InsertintoEmployees values ('Ben', 'Hoskins', 'Male')

InsertintoEmployees values ('Philip', 'Hastings', 'Male')

InsertintoEmployees values ('Mary', 'Lambeth', 'Female')


(1, '[email protected]', '111111111', '111111111')


(2, '[email protected]', '2222222222', '2222222222')


(3, '[email protected]', '3333333333', '3333333333')InsertintoEmployeeContactDetails values

(4, '[email protected]', '44444444444', '44444444444')


(5, '[email protected]', '5555555555', '5555555555')

Step 16:At this point run the application. Insert, update and delete an Employee, and notice that

both the tables (Employees and EmployeeContactDetails) are updated as expected.


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Part 12 - Table splitting in entity framework

Suggested Videos




In this video we will discuss Table splitting in entity framework with database first approach.

Table Splitting is the opposite of Entity Splitting.

We discussed Entity Splitting inPart 10and11ofEntity Framework tutorial.

Entity Splittingrefers to mapping an entity to two or more tables when the tables share a

common key.

Mapping multiple entities to a single table is called table splitting .
http://csharp-video-tutorials.blogspot.com/2014/05/part-9-overriding-stored-procedure.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-9-overriding-stored-procedure.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttps://www.youtube.com/playlist?list=PL6n9fhu94yhUPBSX-E2aJCnCR3-_6zBZxhttps://www.youtube.com/playlist?list=PL6n9fhu94yhUPBSX-E2aJCnCR3-_6zBZxhttps://www.youtube.com/playlist?list=PL6n9fhu94yhUPBSX-E2aJCnCR3-_6zBZxhttps://www.youtube.com/playlist?list=PL6n9fhu94yhUPBSX-E2aJCnCR3-_6zBZxhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-9-overriding-stored-procedure.html


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One common entity framework interview question is, What is the main reason for using Table

Splitting?

Table Splitting is useful when you want to delay the loading of some properties with large data

when using lazy loading.

For example, if you have Employee entity and if it contains Photo property that would return large

binary data, and if we use this Photo property only on a few pages in our application, then it does

not make sense from a performance perspective to load this property every time we load the

Employee entity. Using lazy loading load it only on the pages where we need to display Employee

photo.

We will be using the following Employees table

SQL script to create the table


(



LastName nvarchar(50),Gender nvarchar(50),


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Email nvarchar(50),

Mobile nvarchar(50),

LandLine nvarchar(50)

)

InsertintoEmployees values ('Mark', 'Hastings', 'Male', '[email protected]', 'XXX', 'XXX')

InsertintoEmployees values ('Steve', 'Pound', 'Male', '[email protected]', 'YYY', 'YYY')

InsertintoEmployees values ('Ben', 'Hoskins', 'Male', '[email protected]', 'ZZZ', 'ZZZ')

InsertintoEmployees values ('Philip', 'Hastings', 'Male', '[email protected]', 'AAA', 'AAA')

InsertintoEmployees values ('Mary', 'Lambeth', 'Female', '[email protected]', 'BBB', 'BBB')

Now, when we use ADO.NET Entity Framework to generate entities from the database using

database first approach, by default one entity will be created, i.e Empoyee entity.

Let's say, we will not be using Email, Mobile and Landline properties as often as we would be

using FirstName, LastName, and Gender properties. If all of these properties are present in one

Employee entity, then every time we load this entity, all the properties will be automatically

loaded. So let's create 2 entities (Employee & EmployeeContactDetail). This enables us to load

EmployeeContactDetails only when needed.

To achieve this:

1.Right click on the entity designer and select "Add Entity" option from the context menu. Set

a)Entity Name = EmployeeContactDetail

b)Bae type = (None)c)Entity Set = EmployeeContactDetails

d)Create Key Property = Checked

e)Property Name = EmployeeID


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2.Cut Email, Mobile and LandLine properties from Employee entity and paste them in

EmployeeContactDetail entity

3.Right click on the entity designer and select "Add - Association" option from the context menu.

Fill the details shown below.


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4.Right click on the association and select "Properties". In the Properties window, click on the

ellipsis button next to "Referential Constraint" property and fill in the details as shown below.

5.Right click on "EmployeeContactDetail" entity and select "Table Mapping" option from the


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context menu. Select "Employees" table and map EmployeeId, Email, Mobile andLandline

properties of the entity to the respective columns of the table.

6.Add a webform. Copy and paste the following HTML in the ASPX page.

7.Copy and paste the following code in the code-behind file.

publicpartialclassWebForm1: System.Web.UI.Page

{

privateDataTableGetEmployeeData()

{


List employees = employeeDBContext.Employees.ToList();

DataTabledataTable = newDataTable();DataColumn[] columns = { newDataColumn("EmployeeID"),

newDataColumn("FirstName"),

newDataColumn("LastName"),

newDataColumn("Gender")};

dataTable.Columns.AddRange(columns);

foreach(Employeeemployee inemployees)

{

DataRowdr = dataTable.NewRow();dr["EmployeeID"] = employee.EmployeeID;


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dr["FirstName"] = employee.FirstName;

dr["LastName"] = employee.LastName;

dr["Gender"] = employee.Gender;

dataTable.Rows.Add(dr);

}

returndataTable;

}

privateDataTableGetEmployeeDataIncludingContactDetails()

{


List employees = employeeDBContext.Employees

.Include("EmployeeContactDetail").ToList();

DataTabledataTable = newDataTable();

DataColumn[] columns = { newDataColumn("EmployeeID"),



newDataColumn("Gender"),

newDataColumn("Email"),

newDataColumn("Mobile"),

newDataColumn("LandLine") };


foreach(Employeeemployee inemployees)

{

DataRowdr = dataTable.NewRow();

dr["EmployeeID"] = employee.EmployeeID;


dr["LastName"] = employee.LastName;

dr["Gender"] = employee.Gender;

dr["Email"] = employee.EmployeeContactDetail.Email;

dr["Mobile"] = employee.EmployeeContactDetail.Mobile;

dr["LandLine"] = employee.EmployeeContactDetail.LandLine;


}

returndataTable;

}

protectedvoidButton1_Click(objectsender, EventArgse)

{

if(checkBoxIncludeContactDetails.Checked){


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GridView1.DataSource = GetEmployeeDataIncludingContactDetails();

}

else

{

GridView1.DataSource = GetEmployeeData();

}


}

}

At this point, run the application and when you retrieve Employees without checking "Include

Contact Details" checkbox, the following query is generated by the entity framework. Use SQL

Profilerto view the generated query. Notice that Email, Mobile and LandLine column values are

not loaded.

SELECT

[Extent1].[EmployeeID] AS[EmployeeID],[Extent1].[FirstName] AS[FirstName],

[Extent1].[LastName] AS[LastName],

[Extent1].[Gender] AS[Gender]

FROM[dbo].[Employees] AS[Extent1]

When you check "Include Contact Details" checkbox, the following query is generated

SELECT

[Extent1].[EmployeeID] AS[EmployeeID],

[Extent1].[FirstName] AS[FirstName],

[Extent1].[LastName] AS[LastName],[Extent1].[Gender] AS[Gender],

[Extent1].[Email] AS[Email],

[Extent1].[Mobile] AS[Mobile],

[Extent1].[LandLine] AS[LandLine]



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Part 13 - Table splitting in entity framework with code first approach

Suggested Videos




In this video we will discuss Table splitting in entity framework with code first approach. We

discussed Table Splitting with database first approach inPart 12.

Mapping multiple entities to a single table is called table splitting .

Step 1:Create a new empty asp.net web application project. Name it Demo. Install entity

framework if it's not already installed.

Step 2: Add a class file to the project. Name it Employee.cs. Copy and paste the following code.namespaceDemo

{

publicclassEmployee

{

publicintEmployeeID { get; set; }

publicstringFirstName { get; set; }

publicstringLastName { get; set; }

publicstringGender { get; set; }

publicEmployeeContactDetailEmployeeContactDetail { get; set; }}

}

Step 3:Add a class file to the project. Name it EmployeeContactDetail.cs. Copy and paste the

following code.

namespaceDemo

{

publicclassEmployeeContactDetail

{

publicintEmployeeID { get; set; }publicstringEmail { get; set; }

publicstringMobile { get; set; }

publicstringLandLine { get; set; }

publicEmployeeEmployee { get; set; }

}

}

Step 4:Add a class file to the project. Name it EmployeeDBContext.cs. Copy and paste the

following code.usingSystem.Data.Entity;
http://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-10-entity-splitting-in-entity.html


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namespaceDemo

{


{



{


.HasKey(pk => pk.EmployeeID)

.ToTable("Employees");


.HasKey(pk => pk.EmployeeID)

.ToTable("Employees");


.HasRequired(p => p.EmployeeContactDetail)

.WithRequiredPrincipal(c => c.Employee);

}

}

}


Step 6:Add a web form to the project. Copy and paste the following HTML in the aspx page

Step 7:Copy and paste the following code in the code-behind file.

publicpartialclassWebForm1: System.Web.UI.Page

{

privateDataTable GetEmployeeData()

{EmployeeDBContext employeeDBContext = newEmployeeDBContext();


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List employees = employeeDBContext.Employees.ToList();

DataTable dataTable = newDataTable();




newDataColumn("Gender")};


foreach(Employee employee inemployees)

{

DataRow dr = dataTable.NewRow();



dr["LastName"] = employee.LastName;dr["Gender"] = employee.Gender;


}

returndataTable;

}

privateDataTable GetEmployeeDataIncludingContactDetails()

{EmployeeDBContext employeeDBContext = newEmployeeDBContext();

List employees = employeeDBContext.Employees

.Include("EmployeeContactDetail").ToList();

DataTable dataTable = newDataTable();




newDataColumn("Gender"),

newDataColumn("Email"),newDataColumn("Mobile"),

newDataColumn("LandLine") };


foreach(Employee employee inemployees)

{

DataRow dr = dataTable.NewRow();



dr["LastName"] = employee.LastName;dr["Gender"] = employee.Gender;


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dr["Email"] = employee.EmployeeContactDetail.Email;

dr["Mobile"] = employee.EmployeeContactDetail.Mobile;

dr["LandLine"] = employee.EmployeeContactDetail.LandLine;


}

returndataTable;

}

protectedvoidButton1_Click(objectsender, EventArgs e)

{

if(checkBoxIncludeContactDetails.Checked)

{

GridView1.DataSource = GetEmployeeDataIncludingContactDetails();

}

else{

GridView1.DataSource = GetEmployeeData();

}


}

}

At this point, run the application. Sample database and Employees table should be created by the

entity framework.

Step 8: Insert test data using the following SQL script

InsertintoEmployees values ('Mark', 'Hastings', 'Male', '[email protected]', 'XXX', 'XXX')

InsertintoEmployees values ('Steve', 'Pound', 'Male', '[email protected]', 'YYY', 'YYY')

InsertintoEmployees values ('Ben', 'Hoskins', 'Male', '[email protected]', 'ZZZ', 'ZZZ')

InsertintoEmployees values ('Philip', 'Hastings', 'Male', '[email protected]', 'AAA', 'AAA')

InsertintoEmployees values ('Mary', 'Lambeth', 'Female', '[email protected]', 'BBB', 'BBB')

When you retrieve Employees without checking "Include Contact Details" checkbox, the following

query is generated by the entity framework. Use SQL Profile to view the generated query. Notice

that Email, Mobile and LandLine column values are not loaded.SELECT




[Extent1].[Gender] AS[Gender]


When you check "Include Contact Details" checkbox, the following query is generated

SELECT

[Extent1].[EmployeeID] AS[EmployeeID],[Extent1].[FirstName] AS[FirstName],


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[Extent1].[Gender] AS[Gender],

[Extent1].[Email] AS[Email],

[Extent1].[Mobile] AS[Mobile],

[Extent1].[LandLine] AS[LandLine]


Part 14 - Conditional Mapping in entity framework

Suggested Videos



Part 13 - Table splitting in entity framework with code first approach

In this video we will discuss Conditional Mapping feature in entity framework with database first

approach. Let us understand what Conditional Mapping can do with an example.

We will be using the following Employees table in this demo. IsTerminated column determines if

an employee is a terminated employee or not.

SQL Query to create Employees table


(




Gender nvarchar(50),

IsTerminated bitnot null

)

GO

InsertintoEmployees values ('Mark', 'Hastings', 'Male', 0)

InsertintoEmployees values ('Steve', 'Pound', 'Male', 0)

InsertintoEmployees values ('Ben', 'Hoskins', 'Male', 0)

InsertintoEmployees values ('Philip', 'Hastings', 'Male', 1)

InsertintoEmployees values ('Mary', 'Lambeth', 'Female', 0)

InsertintoEmployees values ('Valarie', 'Vikings', 'Female', 0)

InsertintoEmployees values ('John', 'Stanmore', 'Male', 1)
http://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-13-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-13-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-13-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-12-table-splitting-in-entity.htmlhttp://csharp-video-tutorials.blogspot.com/2014/05/part-11-entity-splitting-in-entity.html


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If the application that we are developing always need only the employees who are not

terminated, then in the query we will have to always include the filter across our entire

application. Conditional Mappingcan be used to apply such a permanent filter on the entity, so

that the generated SQL query always have the WHERE clause.

To use Conditional Mapping,

1.Right click on the entity and select "Table Mapping" option from the context menu

2.Add the condition - When Is Terminated = false

At this point, if you build the solution or validate the model, you will get the following error

Problem in mapping fragments starting at line 46:Condition member 'Employees.IsTerminated'

with a condition other than 'IsNull=False' is mapped. Either remove the condition on

Employees.IsTerminated or remove it from the mapping

This is because, a table column cannot be mapped more than once. We have used IsTerminated

column in conditional mapping, so it cannot be used in property mapping as well. For this reason

delete it from Employee entity.

Add a web form to the project. Drag and drop a GridView control. Copy and paste the following

code in the code-behind file.

protectedvoidPage_Load(objectsender, EventArgse)

{


GridView1.DataSource=employeeDBContext.Employees;GridView1.DataBind();

}

Open SQL profiler and run the webform. Notice that the select query has a where clause, which

will always return employees who are not terminated.

SELECT




[Extent1].[Gender] AS[Gender]FROM[dbo].[Employees] AS[Extent1]


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WHERE[Extent1].[IsTerminated] = 0

Part 15 - Conditional Mapping in entity framework with code first

Suggested Videos


Part 13 - Table splitting

Documents

Entity Framework Video Content