In version 1.1, what we do is utilize the bindModel() and unbindModel(). We do not declare all associations in the Model class yet. This was a good solution. I was looking for this option in version 1.2 and I found the Containable Behavior. Studying containable was a little rough before but there are documents now that are really helpful.

• Cakephp Book: Containable
• CakeBaker: New Core Behavior – Containable
• StudioCanaria: Cakephp Containable Behavior

Today, I’ll be showing you how to use Containable in pagination and in regular find method. You must have a fair understanding of the behavior so I suggest you read the above articles first. If you are ready, follow the instructions below:

1. Download the latest 1.2 release of cake. As of this writing, I tested it in cake_1.2.0.7296-rc2. Do the usual cake installation procedures.
2. Download this file and unzip. It must contain an “app” folder
3. Replace the /app from #1 with the /app from #2 but leave the config file of #1.
4. Use the /app/class.sql to setup your database

The idea of the sample is taken from a virtual school application. So we have Departments, Courses, Classes, Students and Teachers, Students Comments on Class and Students Ratings on Class. The following is an explanation of tables declared in class.sql so you can follow the relationships:

Exampe1: List of Classes

What we will do is get only the basic information for the list of classes. Those includes:

• Class title
• Course it belongs to
• Department it belongs to
• Teacher name

It will look like this (replace the http://localhost with your local address)
http://localhost/cake/my_classes/index

Let’s compare the recursive and containable method.

Using The Recursive Method
Check the MyClassesController::unfiltered_result() for your reference. First try is I added the ffg line
$this->MyClass->recursive = 1;
but the problem is that I could not get the Department name. Then I tried
$this->MyClass->recursive = 2;
and there I have all the information I need. The problem is that there are just to many data I do not need. Another option is to use the the paginate fields filter. Try adding this:
$this->paginate['MyClass']['fields'] = array( 'Course.title', 'MyClass.title' );

The result? Check it for yourself in http://localhost/cake/my_classes/unfiltered_result

Using Containable Behavior
If you look at MyClassesController::index2(), you would see the ffg:

$this->paginate['MyClass']['contain'] = array (
'Teacher',
'Course' => array (
'Department' => array (
'fields' => array (
'Department.title',
'Department.id'
)
)
)
);

That basically tells cake to find the Class Teacher and return all fields, the course it belongs to and return all the fields and finally the course’ Department title and ID. Now run this http://localhost/cake/my_classes/filtered_result and compare the result with the previous example. It became cleaner isn’t it?

With Containable, you can specify which tables to include and what fields to include each table. You can also add order and limit filters and also conditions. It took me a while to grasp the format because at first glance it is a bit difficult to follow. I use the following format:


$this->Model0->contain( array(
'Model1' => array (
'fields' => array( 'modelField1', 'modelField2' ),
'conditions' => array( 'your condition here' ),
'order' => array( 'id' => 'asc' ),
),
'Model2',
'Model2'
)
)


Example2: Class View

This is just to show you a more complicated containable query. We want to get more information about the class. That includes:

• Class title
• Course it belongs to
• Department it belongs to
• Teacher name
• Student comments that were approved and student name
• Student ratings that were approved and student name

We can achieve the desired results using recursive but then again we will be wasting so much process time. In containable, we’ll just have to declare what we want.


$this->MyClass->contain( array(
'Teacher',
'Rating' => array(
'Student',
'order' => array( 'created' => 'desc' ),
'conditions' => array( 'approved' => 1 )
),
'Comment' => array(
'Student',
'order' => array( 'RAND()' ),
'limit' => 3 ,
'conditions' => array( 'approved' => 1 )
),
'Course' => array(
'Department' => array(
'fields' => array(
'Department.title',
'Department.id'
)
)
)
)
);


Can you see the format now? Play around with the codes and check their results to get more comfortable with it. Happy Baking!

One nice thing I like about cake is the use of MVC pattern which makes my codes more organized. And I like how the querying is done which is made more simple because you wouldn’t need to declare associated tables within your query if you have already specified the associations within your model. Fantastic! One of the most powerful features of CakePHP is the relational mapping provided by the model. At first, I didn’t want to touch anything in the models coz I was confused about associations. Besides I was scared I might break the code. But when I finally understood how, I declared the necessary associations within my models most especially “messages”, coz in isupport this is often being used and it has a lot of associated tables in it. But sometimes, when you query, your association settings in the model file are giving you too much (or not enough) information. What I mean to say is, sometimes you wouldn’t need some of the associated tables in your query result. So you have to think of a way how to minimize the result, and that is where unbindModel & bindModel model functions are used which allow you to change your association settings on the fly. But as quoted from the bakery section of cakephp.org by TommyO,

Changing the requirements of a bind done in this way means going through your controllers and changing the bindModel call, often in multiple places. Using unbindModel in a controller also means every time a new association is added you may need to go back into your controllers and unbind the new associations in order to optimize your code.

Silly, but true. Thanks to TommyO, he created a method to simplify this using the approach:

binding to other Models only when needed or unbinding existing relations to minimize the size of your result set.

But just an overview, you would just need to add a function within your appmodel. Then in your model class, just define your associations within an array called $assoc. You will see an example from the link. So easy huh?

So in your controller:

<?php
MessageController extends AppController {
function index($id) {
// establish necessary associations
$this->Message->expects(array('Comments', 'User'));
$results = $this->Message->findAll();
}
}
?>

Now you have it. But that’s not all. Ive read another post in the bakery related to TommyO’s method for model associations. In TommyO’s approach, there’s a slight difference on the way you define your model association and the models get loaded *when* you call the expects() function. According to Mariano, the author of the post, he said he’s not a fan of changing how things are done in cakephp, neither do I. His approach is to use the Cakephp way of defining associations in the models and then specify which relations he’s interested in getting back when querying a model. This way, models behave the way models are supposed to. The main idea here is that you define your associations in the model the cakephp way. Then in your controller, if you want the standard result cakephp brings then you don’t need to call expects() (With TommyO’s approach, you will need to call expects() with all the necessary values). Use expects(), only when you want to limit the result of your query. And if you want to unbindAll just call expects() with no parameters. You will need to add three functions in your appmodel which you will find here. There are additional topics included here like “making multiple expects in one call“. And if I’m a little confusing in explaining, I think you can understand it better when you visit the links. hehehehe.

Good luck!