A BLINK INTO THE “RAILS MAGIC”

The meta-programming in Rails / Rails as a code generator

Some rights reservedNikos Dimitrakopoulos, 2009

http://blog.nikosd.com

The “classic” rails ingredients

MVCDRYCOC…

Not for today…

MVCDRYCOC…

Rails as a code generator

PART I :

100% Static

The directory structure

Models + Tests

Controllers / views + tests

Resources (the whole set)

Even with *implemented* views & controllers (a.k.a. “scaffolds”)

Static(*) API

Nothing special so far…

PART II :

100% On-the-fly

This is where the actual fun begins!

Some basic stuff: ORM

How does Rails map the attributes???

The truth is in the source…

A blink into the “magic”

if we haven’t already generated the “dynamic” methods

if we haven’t already generated the “dynamic” methods

• generate them

if we haven’t already generated the “dynamic” methods

• generate them

•try to call the method with the given name again!

for each column on the db table :

for each column on the db table :

• define a “read” method

for each column on the db table :

• define a “read” method (for example the Guest#name)

for each column on the db table :

• define a “read” method(for example the Guest#name)

• define a “write” method

for each column on the db table :

• define a “read” method(for example the Guest#name)

• define a “write” method(for example the Guest#name = …)

for each column on the db table :

• define a “read” method(for example the Guest#name)

• define a “write” method(for example the Guest#name = …)

• define a “question” method

for each column on the db table :

• define a “read” method(for example the Guest#name)

• define a “write” method(for example the Guest#name = …)

• define a “question” method(for example the Guest#name?)

PART III :

Magic happens Everywhere

On the routes / Controllers

+ 3 more by default

More info on “resources” : http://api.rubyonrails.org/classes/ActionController/Resources.html

+ 3 more by default

On the ORM / Models

Dynamic finders

Dynamic finders

As said this is just a “blink”

Look for more in :

• ActiveRecord associations• ActiveRecord named_scopes

• ActionController routes• ActionController rendering• ActionController format

• etc…

What do we get from this?

What do we get from this?

•Glue code

What do we get from this?

•Glue code•Domain-aware code

What do we get from this?

•Glue code•Domain-aware code

•Out of the box

What do we get from this?

•Glue code•Domain-aware code

•Out of the box• Every time

What do we get from this?

• Glue code• Domain-aware code

• Out of the box• Every time

• On every app

Compare it with Java or .Net “enterprise”

solutions…

Compare it with Java or .Net “enterprise”

solutions…

© Rubyrags.com

Implement your own!!!

Implement your own!!!

(Jim will give you a hint tomorrow at the Ruby

Meetup)

Thanks for your time

Thanks for your time

And welcome to the magic world of

Ruby and Ruby on Rails