Models¶

Example User Model, saved in /app/models/user.php¶

<?php

//AppModel gives you all of Cake's Model functionality

class User extends AppModel
{
    // Its always good practice to include this variable.
    var $name = 'User';

    // This is used for validation, see Chapter "Data Validation".
    var $validate = array();

    // You can also define associations.
    // See section 6.3 for more information.

    var $hasMany = array('Image' =>
                   array('className' => 'Image')
                   );

    // You can also include your own functions:
    function makeInactive($uid)
    {
        //Put your own logic here...
    }
}

User-Defined Functions¶

An example of a table-specific method in the model is a pair of methods for hiding/unhiding posts in a blog.

Example Model Functions¶

<?php
class Post extends AppModel
{
   var $name = 'Post';

   function hide ($id=null)
   {
      if ($id)
      {
          $this->id = $id;
          $this->saveField('hidden', '1');
      }
   }

   function unhide ($id=null)
   {
      if ($id)
      {
          $this->id = $id;
          $this->saveField('hidden', '0');
      }
   }
}

Retrieving Your Data¶

Below are a few of the standard ways of getting to your data using a model:

• findAll

• string $conditions

• array $fields

• string $order

• int $limit

• int $page

• int $recursive

Returns the specified fields up to $limit records matching $conditions (if any), start listing from page $page (default is page 1). $conditions should look like they would in an SQL statement: $conditions = “race = ‘wookie’ AND thermal_detonators > 3”, for example.

When the $recursive option is set to an integer value greater than 1, the findAll() operation will make an effort to return the models associated to the ones found by the findAll(). If your property has many owners who in turn have many contracts, a recursive findAll() on your Property model will return those associated models.

Set $recursive to -1 if you want no associated data fetched during the find.

• find

• string $conditions

• array $fields

• string $order

• int $recursive

Returns the specified (or all if not specified) fields from the first record that matches $conditions.

When the $recursive option is set to an integer value between 1 and 3, the find() operation will make an effort to return the models associated to the ones found by the find(). The recursive find can go up to three levels deep. If your property has many owners who in turn have many contracts, a recursive find() on your Property model will return up to three levels deep of associated models.

Set $recursive to -1 if you want no associated data fetched durint the find.

• findBy<fieldName>

• string $value

• findAllBy<fieldName>

• string $value

These magic functions can be used as a shortcut to search your tables for a row given a certain field, and a certain value. Just tack on the name of the field you wish to search, and CamelCase it (depending on your PHP version). Examples (as used in a Controller) might be:

<?php
//PHP 5 Users
$this->Post->findByTitle('My First Blog Post');
$this->Author->findByLastName('Rogers');
$this->Property->findAllByState('AZ');
$this->Specimen->findAllByKingdom('Animalia');
$this->Foo->findAllByThreeWordField('bar');

//PHP 4 Users
$this->Post->findByTitle('My First Blog Post');
$this->Author->findByLast_name('Rogers');        //PHP4 isn't as case-friendly
$this->Property->findAllByState('AZ');
$this->Specimen->findAllByKingdom('Animalia');
$this->Foo->findAllByThree_word_field('bar');    //PHP4 isn't as case-friendly

The returned result is an array formatted just as would be from find() or findAll().

• findNeighbours

• string $conditions

• array $field

• string $value

Returns an array with the neighboring models (with only the specified fields), specified by $field and $value, filtered by the SQL conditions, $conditions.

This is useful in situations where you want ‘Previous’ and ‘Next’ links that walk users through some ordered sequence through your model entries. It only works for numeric and date based fields:

<?php
class ImagesController extends AppController
{
    function view($id)
    {
        // Say we want to show the image...

        $this->set('image', $this->Image->find("id = $id"));

        // But we also want the previous and next images...

        $this->set('neighbours', $this->Image->findNeighbours(null, 'id', $id));

    }
}

This gives us the full $image[‘Image’] array, along with $neighbours[‘prev’][‘Image’][‘id’] and $neighbours[‘next’][‘Image’][‘id’] in our view.

• field

• string $name

• string $conditions

• string $order

Returns as a string a single field from the first record matched by $conditions as ordered by $order.

• findCount

• string $conditions

Returns the number of records that match the given conditions.

• generateList

• string $conditions

• string $order

• int $limit

• string $keyPath

• string $valuePath

This function is a shortcut to getting a list of key value pairs - especially handy for creating a html select tag from a list of your models. Use the $conditions, $order, and $limit parameters just as you would for a findAll() request. The $keyPath and $valuePath are where you tell the model where to find the keys and values for your generated list. For example, if you wanted to generate a list of roles based on your Role model, keyed by their integer ids, the full call might look something like:

<?php
$this->set(
    'Roles',
    $this->Role->generateList(null, 'role_name ASC', null, '{n}.Role.id', '{n}.Role.role_name')
);

//This would return something like:
array(
    '1' => 'Account Manager',
    '2' => 'Account Viewer',
    '3' => 'System Manager',
    '4' => 'Site Visitor'
);

• read

• string $fields

• string $id

Use this function to get the fields and their values from the currently loaded record, or the record specified by $id.

The recursiveness of the result depends on the value of $recursive in the model.

• query

• string $query

• execute

• string $query

Custom SQL calls can be made using the model’s query() and execute() methods. The difference between the two is that query() is used to make custom SQL queries (the results of which are returned), and execute() is used to make custom SQL commands (which require no return value).

Custom Sql Calls with query()¶

<?php
class Post extends AppModel
{
    var $name = 'Post';

    function posterFirstName()
    {
        $ret = $this->query("SELECT first_name FROM posters_table
                                 WHERE poster_id = 1");
        $firstName = $ret[0]['first_name'];
        return $firstName;
    }
}

Complex Find Conditions (using arrays)¶

Most of the model’s finder calls involve passing sets of conditions in one way or another. The simplest approach to this is to use a WHERE clause snippet of SQL, but if you need more control, you can use arrays. Using arrays is clearer and easier to read, and also makes it very easy to build queries. This syntax also breaks out the elements of your query (fields, values, operators, etc.) into discrete, manipulatable parts. This allows Cake to generate the most efficient query possible, ensure proper SQL syntax, and properly escape each individual part of the query.

At it’s most basic, an array-based query looks like this:

Basic find conditions array usage example:¶

<?php
$conditions = array("Post.title" => "This is a post");

//Example usage with a model:
$this->Post->find($conditions);

The structure is fairly self-explanatory: it will find any post where the title matches the string “This is a post”. Note that we could have used just “title” as the field name, but when building queries, it is good practice to always specify the model name, as it improves the clarity of the code, and helps prevent collisions in the future, should you choose to change your schema. What about other types of matches? These are equally simple. Let’s say we wanted to find all the posts where the title is not “This is a post”:

<?php
array("Post.title" => "<> This is a post")

All that was added was ‘<>’ before the expression. Cake can parse out any valid SQL comparison operator, including match expressions using LIKE, BETWEEN, or REGEX, as long as you leave a space between the operator an the expression or value. The one exception here is IN (…)-style matches. Let’s say you wanted to find posts where the title was in a given set of values:

<?php
array("Post.title" => array("First post", "Second post", "Third post"))

Adding additional filters to the conditions is as simple as adding additional key/value pairs to the array:

<?php
array
(
    "Post.title"   => array("First post", "Second post", "Third post"),
    "Post.created" => "> " . date('Y-m-d', strtotime("-2 weeks"))
)

By default, Cake joins multiple conditions with boolean AND; which means, the snippet above would only match posts that have been created in the past two weeks, and have a title that matches one in the given set. However, we could just as easily find posts that match either condition:

<?php
array
("or" =>
    array
    (
        "Post.title" => array("First post", "Second post", "Third post"),
        "Post.created" => "> " . date('Y-m-d', strtotime("-2 weeks"))
    )
)

Cake accepts all valid SQL boolean operations, including AND, OR, NOT, XOR, etc., and they can be upper or lower case, whichever you prefer. These conditions are also infinitely nestable. Let’s say you had a hasMany/belongsTo relationship between Posts and Authors, which would result in a LEFT JOIN on the find done on Post. Let’s say you wanted to find all the posts that contained a certain keyword or were created in the past two weeks, but you want to restrict your search to posts written by Bob:

<?php
array
("Author.name" => "Bob", "or" => array
    (
        "Post.title" => "LIKE %magic%",
        "Post.created" => "> " . date('Y-m-d', strtotime("-2 weeks")
    )
)

Model::recursive options¶

$transactional

Tells Cake whether or not to enable transactions for this model (i.e. begin/commit/rollback). Set to a boolean value. Only available for supporting databases.

$useTable

If the database table you wish to use isn’t the plural form of the model name (and you don’t wish to change the table name), set this variable to the name of the table you’d like this model to use.

$validate

An array used to validate the data passed to this model. See Chapter “Data Validation”.

$useDbConfig

Remember the database settings you can configure in /app/config/database.php? Use this variable to switch between them - just use the name of the database connection variable you’ve created in your database configuration file. The default is, you guessed it, ‘default’.

Introduction¶

One of the most powerful features of CakePHP is the relational mapping provided by the model. In CakePHP, the links between tables are handled through associations. Associations are the glue between related logical units.

There are four types of associations in CakePHP:

1. hasOne

2. hasMany

3. belongsTo

4. hasAndBelongsToMany

When associations between models have been defined, Cake will automagically fetch models related to the model you are working with. For example, if a Post model is related to an Author model using a hasMany association, making a call to $this->Post->findAll() in a controller will fetch Post records, as well as all the Author records they are related to.

To use the association correctly it is best to follow the CakePHP naming conventions (see Appendix “Cake Conventions”). If you use CakePHP’s naming conventions, you can use scaffolding to visualize your application data, because scaffolding detects and uses the associations between models. Of course you can always customize model associations to work outside of Cake’s naming conventions, but we’ll save those tips for later. For now, let’s just stick to the conventions. The naming conventions that concern us here are the foreign keys, model names, and table names.

Here’s a review of what Cake expects for the names of these different elements: (see Appendix “Cake Conventions” for more information on naming)

• Foreign Keys: [singular model name]_id. For example, a foreign key in the “authors” table pointing back to the Post a given Author belongs to would be named “post_id”.

• Table Names: [plural object name]. Since we’d like to store information about blog posts and their authors, the table names are “posts” and “authors”, respectively.

• Model Names: [CamelCased, singular form of table name]. The model name for the “posts” table is “Post”, and the model name for the “authors” table is “Author”.

CakePHP’s scaffolding expects your associations to be in the same order as your columns. So if I have an Article that belongsTo three other models (Author, Editor, and Publisher), I would need three keys: author_id, editor_id, and publisher_id. Scaffolding would expect your associations in the same order as the keys in the table (e.g. first Author, second Editor, lastly Publisher).

In order to illustrate how some of these associations work, let’s continue using the blog application as an example. Imagine that we’re going to create a simple user management system for the blog. I suppose it goes without saying we’ll want to keep track of Users, but we’d also like each user to have an associated Profile (User hasOne Profile). Users will also be able to create comments and remain associated to them (User hasMany Comments). Once we have the user system working, we’ll move to allowing Posts to be related to Tag objects using the hasAndBelongsToMany relationship (Post hasAndBelongsToMany Tags).

Defining and Querying with hasOne¶

In order to set up this association, we’ll assume that you’ve already created the User and Profile models. To define the hasOne assocation between them, we’ll need to add an array to the models to tell Cake how they relate:

/app/models/user.php hasOne¶

<?php
class User extends AppModel
{
    var $name = 'User';
    var $hasOne = array('Profile' =>
                        array('className'    => 'Profile',
                              'conditions'   => '',
                              'order'        => '',
                              'dependent'    =>  true,
                              'foreignKey'   => 'user_id'
                        )
                  );
}

The $hasOne array is what Cake uses to build the association between the User and Profile models. Each key in the array allows you to further configure the association:

1. className (required): the classname of the model you’d like to associate

   For our example, we want to specify the ‘Profile’ model class name.

2. conditions: SQL condition fragments that define the relationship

   We could use this to tell Cake to only associate a Profile that has a green header, if we wished. To define conditions like this, you’d specify a SQL conditions fragment as the value for this key: “Profile.header_color = ‘green’”.

3. order: the ordering of the associated models

   If you’d like your associated models in a specific order, set the value for this key using an SQL order predicate: “Profile.name ASC”, for example.

4. dependent: if set to true, the associated model is destroyed when this one is.

   For example, if the “Cool Blue” profile is associated to “Bob”, and I delete the user “Bob”, the profile “Cool Blue” will also be deleted.

5. foreignKey: the name of the foreign key that points to the associated model.

   This is here in case you’re working with a database that doesn’t follow Cake’s naming conventions.

Now, when we execute find() or findAll() calls using the Profile model, we should see our associated User model there as well:

<?php
$user = $this->User->read(null, '25');
print_r($user);

//output:

Array
(
    [User] => Array
        (
            [id] => 25
            [first_name] => John
            [last_name] => Anderson
            [username] => psychic
            [password] => c4k3roxx
        )

    [Profile] => Array
        (
            [id] => 4
            [name] => Cool Blue
            [header_color] => aquamarine
            [user_id] = 25
        )
)

Defining and Querying with belongsTo¶

Now that a User can see its Profile, we’ll need to define an association so Profile can see its User. This is done in Cake using the belongsTo assocation. In the Profile model, we’d do the following:

/app/models/profile.php belongsTo¶

<?php
class Profile extends AppModel
{
    var $name = 'Profile';
    var $belongsTo = array('User' =>
                           array('className'  => 'User',
                                 'conditions' => '',
                                 'order'      => '',
                                 'foreignKey' => 'user_id'
                           )
                     );
}

The $belongsTo array is what Cake uses to build the association between the User and Profile models. Each key in the array allows you to further configure the association:

1. className (required): the classname of the model you’d like to associate

   For our example, we want to specify the ‘User’ model class name.

2. conditions: SQL condition fragments that define the relationship

   We could use this to tell Cake to only associate a User that is active. You would do this by setting the value of the key to be “User.active = ‘1’”, or something similar.

3. order: the ordering of the associated models

   If you’d like your associated models in a specific order, set the value for this key using an SQL order predicate: “User.last_name ASC”, for example.

4. foreignKey: the name of the foreign key that points to the associated model.

   This is here in case you’re working with a database that doesn’t follow Cake’s naming conventions.

Now, when we execute find() or findAll() calls using the Profile model, we should see our associated User model there as well:

<?php
$profile = $this->Profile->read(null, '4');
print_r($profile);

//output:

Array
(

    [Profile] => Array
        (
            [id] => 4
            [name] => Cool Blue
            [header_color] => aquamarine
            [user_id] = 25
        )

    [User] => Array
        (
            [id] => 25
            [first_name] => John
            [last_name] => Anderson
            [username] => psychic
            [password] => c4k3roxx
        )
)

/app/models/user.php hasMany¶

<?php
class User extends AppModel
{
    var $name = 'User';
    var $hasMany = array('Comment' =>
                         array('className'     => 'Comment',
                               'conditions'    => 'Comment.moderated = 1',
                               'order'         => 'Comment.created DESC',
                               'limit'         => '5',
                               'foreignKey'    => 'user_id',
                               'dependent'     => true,
                               'exclusive'     => false,
                               'finderQuery'   => '',
                               'fields'        => '',
                               'offset'        => '',
                               'counterQuery'  => ''
                         )
                  );

    // Here's the hasOne relationship we defined earlier...
    var $hasOne = array('Profile' =>
                        array('className'    => 'Profile',
                              'conditions'   => '',
                              'order'        => '',
                              'dependent'    =>  true,
                              'foreignKey'   => 'user_id'
                        )
                  );
}

The $hasMany array is what Cake uses to build the association between the User and Comment models. Each key in the array allows you to further configure the association:

1. className (required): the classname of the model you’d like to associate

   For our example, we want to specify the ‘Comment’ model class name.

2. conditions: SQL condition fragments that define the relationship

   We could use this to tell Cake to only associate a Comment that has been moderated. You would do this by setting the value of the key to be “Comment.moderated = 1”, or something similar.

3. order: the ordering of the associated models

   If you’d like your associated models in a specific order, set the value for this key using an SQL order predicate: “Comment.created DESC”, for example.

4. limit: the maximum number of associated models you’d like Cake to fetch.

   For this example, we didn’t want to fetch *all* of the user’s comments, just five.

5. foreignKey: the name of the foreign key that points to the associated model.

   This is here in case you’re working with a database that doesn’t follow Cake’s naming conventions.

6. dependent: if set to true, the associated models are destroyed when this one is.

   For example, if the “Cool Blue” and “Hot Red” profiles are associated to “Bob”, and I delete the user “Bob”, the profiles “Cool Blue” and “Hot Red” will also be deleted.

7. exclusive: If set to true, all the associated objects are deleted in one SQL statement without having their beforeDelete callback run.

   Good for use for simpler associations, because it can be much faster.

8. finderQuery: Specify a complete SQL statement to fetch the association.

   This is a good way to go for complex associations that depends on multiple tables. If Cake’s automatic assocations aren’t working for you, here’s where you customize it.

9. fields: Specify the fields from the associated model you wish to fetch.

   This is useful for associations where not all the fields are needed with every find() call. Limiting the amount of fields you request can increase database performance.

10. offset: The number of records to skip before associating to the current model.

11. counterQuery: Specify a complete SQL statement used to count the number of records that should be associated.

Now, when we execute find() or findAll() calls using the User model, we should see our associated Comment models there as well:

<?php
$user = $this->User->read(null, '25');
print_r($user);

//output:

Array
(
    [User] => Array
        (
            [id] => 25
            [first_name] => John
            [last_name] => Anderson
            [username] => psychic
            [password] => c4k3roxx
        )

    [Profile] => Array
        (
            [id] => 4
            [name] => Cool Blue
            [header_color] => aquamarine
            [user_id] = 25
        )

    [Comment] => Array
        (
            [0] => Array
                (
                    [id] => 247
                    [user_id] => 25
                    [body] => The hasMany assocation is nice to have.
                )

            [1] => Array
                (
                    [id] => 256
                    [user_id] => 25
                    [body] => The hasMany assocation is really nice to have.
                )

            [2] => Array
                (
                    [id] => 269
                    [user_id] => 25
                    [body] => The hasMany assocation is really, really nice to have.
                )

            [3] => Array
                (
                    [id] => 285
                    [user_id] => 25
                    [body] => The hasMany assocation is extremely nice to have.
                )

            [4] => Array
                (
                    [id] => 286
                    [user_id] => 25
                    [body] => The hasMany assocation is super nice to have.
                )

        )
)

While we won’t document the process here, it would be a great idea to define the “Comment belongsTo User” association as well, so that both models can see each other. Not defining assocations from both models is often a common gotcha when trying to use scaffolding.

HABTM Join Tables: Sample models and their join table names¶

1. Posts and Tags: posts_tags

2. Monkeys and IceCubes: ice_cubes_monkeys

3. Categories and Articles: articles_categories

HABTM join tables need to at least consist of the two foreign keys of the models they link. For our example, “post_id” and “tag_id” is all we’ll need.

Here’s what the SQL dumps will look like for our Posts HABTM Tags example:

--
-- Table structure for table `posts`
--

CREATE TABLE `posts` (
  `id` int(10) unsigned NOT NULL auto_increment,
  `user_id` int(10) default NULL,
  `title` varchar(50) default NULL,
  `body` text,
  `created` datetime default NULL,
  `modified` datetime default NULL,
  `status` tinyint(1) NOT NULL default '0',
  PRIMARY KEY  (`id`)
) TYPE=MyISAM;

-- --------------------------------------------------------

--
-- Table structure for table `posts_tags`
--

CREATE TABLE `posts_tags` (
  `post_id` int(10) unsigned NOT NULL default '0',
  `tag_id` int(10) unsigned NOT NULL default '0',
  PRIMARY KEY  (`post_id`,`tag_id`)
) TYPE=MyISAM;

-- --------------------------------------------------------

--
-- Table structure for table `tags`
--

CREATE TABLE `tags` (
  `id` int(10) unsigned NOT NULL auto_increment,
  `tag` varchar(100) default NULL,
  PRIMARY KEY  (`id`)
) TYPE=MyISAM;

With our tables set up, let’s define the association in the Post model:

/app/models/post.php hasAndBelongsToMany¶

<?php
class Post extends AppModel
{
    var $name = 'Post';
    var $hasAndBelongsToMany = array('Tag' =>
                               array('className'    => 'Tag',
                                     'joinTable'    => 'posts_tags',
                                     'foreignKey'   => 'post_id',
                                     'associationForeignKey'=> 'tag_id',
                                     'conditions'   => '',
                                     'order'        => '',
                                     'limit'        => '',
                                     'unique'       => true,
                                     'finderQuery'  => '',
                                     'deleteQuery'  => '',
                               )
                               );
}
?>

The $hasAndBelongsToMany array is what Cake uses to build the association between the Post and Tag models. Each key in the array allows you to further configure the association:

1. className (required): the classname of the model you’d like to associate

   For our example, we want to specify the ‘Tag’ model class name.

2. joinTable: this is here for a database that doesn’t adhere to Cake’s naming conventions. If your table doesn’t look like [plural model1]_[plural model2] in lexical order, you can specify the name of your table here.

3. foreignKey: the name of the foreign key in the join table that points to the current model.

   This is here in case you’re working with a database that doesn’t follow Cake’s naming conventions.

4. associationForeignKey: the name of the foreign key that points to the associated model.

5. conditions: SQL condition fragments that define the relationship

   We could use this to tell Cake to only associate a Tag that has been approved. You would do this by setting the value of the key to be “Tag.approved = 1”, or something similar.

6. order: the ordering of the associated models

   If you’d like your associated models in a specific order, set the value for this key using an SQL order predicate: “Tag.tag DESC”, for example.

7. limit: the maximum number of associated models you’d like Cake to fetch.

   Used to limit the number of associated Tags to be fetched.

8. unique: If set to true, duplicate associated objects will be ignored by accessors and query methods.

   Basically, if the associations are distinct, set this to true. That way the Tag “Awesomeness” can only be assigned to the Post “Cake Model Associations” once, and will only show up once in result arrays.

9. finderQuery: Specify a complete SQL statement to fetch the association.

   This is a good way to go for complex associations that depends on multiple tables. If Cake’s automatic assocations aren’t working for you, here’s where you customize it.

10. deleteQuery: A complete SQL statement to be used to remove assocations between HABTM models.

    If you don’t like the way Cake is performing deletes, or your setup is customized in some way, you can change the way deletion works by supplying your own query here.

Now, when we execute find() or findAll() calls using the Post model, we should see our associated Tag models there as well:

<?php
$post = $this->Post->read(null, '2');
print_r($post);

//output:

Array
(
    [Post] => Array
        (
            [id] => 2
            [user_id] => 25
            [title] => Cake Model Associations
            [body] => Time saving, easy, and powerful.
            [created] => 2006-04-15 09:33:24
            [modified] => 2006-04-15 09:33:24
            [status] => 1
        )

    [Tag] => Array
        (
            [0] => Array
                (
                    [id] => 247
                    [tag] => CakePHP
                )

            [1] => Array
                (
                    [id] => 256
                    [tag] => Powerful Software
                )
        )
)

/app/controllers/posts_controller.php (partial)¶

<?php
function add()
{
    if (!empty($this->data))
    {
        //We can save the Post data:
        //it should be in $this->data['Post']

        $this->Post->save($this->data);

        //Now, we'll need to save the Comment data
        //But first, we need to know the ID for the
        //Post we just saved...

        $post_id = $this->Post->getLastInsertId();

        //Now we add this information to the save data
        //and save the comment.

        $this->data['Comment']['post_id'] = $post_id;

        //Because our Post hasMany Comments, we can access
        //the Comment model through the Post model:

        $this->Post->Comment->save($this->data);

    }
}

If, however, the parent model already exists in the system (for example, adding a Comment to an existing Post), you need to know the ID of the parent model before saving. You could pass this ID as a URL parameter, or as a hidden element in a form…

/app/controllers/posts_controller.php (partial)¶

<?php
//Here's how it would look if the URL param is used...
function addComment($post_id)
{
    if (!empty($this->data))
    {
        //You might want to make the $post_id data more safe,
        //but this will suffice for a working example..

        $this->data['Comment']['post_id'] = $post_id;

        //Because our Post hasMany Comments, we can access
        //the Comment model through the Post model:

        $this->Post->Comment->save($this->data);
    }
}

If the ID was passed as a hidden element in the form, you might want to name the field (if you’re using the HtmlHelper) so it ends up in the posted data where it needs to be:

If the ID for the post is at $post[‘Post’][‘id’]:

<?php echo $html->hidden('Comment/post_id', array('value' => $post['Post']['id'])); ?>

Done this way, the ID for the parent Post model can be accessed at $this->data[‘Comment’][‘post_id’], and is all ready for a simple $this->Post->Comment->save($this->data) call.

These same basic techniques will work if you’re saving multiple child models, just place those save() calls in a loop (and remember to clear the model information using Model::create()).

In summary, if you’re saving associated data (for belongsTo, hasOne, and hasMany relations), the main point is getting the ID of the parent model and saving it to the child model.

Saving hasAndBelongsToMany Relations¶

Saving models that are associated by hasOne, belongsTo, and hasMany is pretty simple: you just populate the foreign key field with the ID of the associated model. Once that’s done, you just call the save() method on the model, and everything gets linked up correctly.

With hasAndBelongsToMany, its a bit trickier, but we’ve gone out of our way to make it as simple as possible. In keeping along with our example, we’ll need to make some sort of form that relates Tags to Posts. Let’s now create a form that creates posts, and associates them to an existing list of Tags.

You might actually like to create a form that creates new tags and associates them on the fly - but for simplicity’s sake, we’ll just show you how to associate them and let you take it from there.

When you’re saving a model on its own in Cake, the tag name (if you’re using the Html Helper) looks like ‘Model/field_name’. Let’s just start out with the part of the form that creates our post:

/app/views/posts/add.thtml Form for creating posts¶

<h1>Write a new post</h1>
<form method="post" action="<?php echo $html->url('/posts/add'); ?>">
<table>
    <tr>
        <td>Title:</td>
        <td><?php echo $html->input('Post/title')?></td>
    </tr>
    <tr>
        <td>Body:<td>
        <td><?php echo $html->textarea('Post/body')?></td>
    </tr>
    <tr>
        <td colspan="2">
            <?php echo $html->hidden('Post/user_id', array('value' => $session->read('User.id')))?>
            <?php echo $html->hidden('Post/status' , array('value' => '0'))?>
            <?php echo $html->submit('Save Post')?>
        </td>
    </tr>
</table>
</form>

The form as it stands now will just create Post records. Let’s add some code to allow us to bind a given Post to one or many Tags:

/app/views/posts/add.thtml (Tag association code added)¶

<h1>Write a new post</h1>
<form method="post" action="<?php echo $html->url('/posts/add'); ?>">
<table>
    <tr>
        <td>Title:</td>
        <td><?php echo $html->input('Post/title')?></td>
    </tr>
    <tr>
        <td>Body:</td>
        <td><?php echo $html->textarea('Post/body')?></td>
    </tr>
    <tr>
        <td>Related Tags:</td>
        <td><?php echo $html->selectTag('Tag/Tag', $tags, null, array('multiple' => 'multiple')) ?>
        </td>
    </tr>
    <tr>
        <td colspan="2">
            <?php echo $html->hidden('Post/user_id', array('value' => $session->read('User.id')))?>
            <?php echo $html->hidden('Post/status' , array('value' => '0'))?>
            <?php echo $html->submit('Save Post')?>
        </td>
    </tr>
</table>
</form>

In order for a call to $this->Post->save() in the controller to save the links between this new Post and its associated Tags, the name of the field must be in the form “Tag/Tag” (the rendered name attribute would look something like ‘data[ModelName][ModelName][]’). The submitted data must be a single ID, or an array of IDs of linked records. Because we’re using a multiple select here, the submitted data for Tag/Tag will be an array of IDs.

The $tags variable here is just an array where the keys are the IDs of the possible Tags, and the values are the displayed names of the Tags in the multi-select element.

leader.php and follower.php¶

<?php

class Leader extends AppModel
{
    var $name = 'Leader';

    var $hasMany = array(
        'Follower' => array(
            'className' => 'Follower',
            'order'     => 'Follower.rank'
        )
    );
}

?>

<?php

class Follower extends AppModel
{
    var $name = 'Follower';
}

?>

Now, in a LeadersController, we can use the find() method in the Leader Model to come up with a Leader and its associated followers. As you can see above, the association array in the Leader model defines a “Leader hasMany Followers” relationship. For demonstration purposes, let’s use unbindModel() to remove that association mid-controller.

leaders_controller.php (partial)¶

<?php
function someAction()
{
    //This fetches Leaders, and their associated Followers
    $this->Leader->findAll();

    //Let's remove the hasMany...
    $this->Leader->unbindModel(array('hasMany' => array('Follower')));

    //Now a using a find function will return Leaders, with no Followers
    $this->Leader->findAll();

    //NOTE: unbindModel only affects the very next find function.
    //An additional find call will use the configured association information.

    //We've already used findAll() after unbindModel(), so this will fetch
    //Leaders with associated Followers once again...
    $this->Leader->findAll();
}

The unbindModel() function works similarly with other associations: just change the name of the association type and model classname. The basic usage for unbindModel() is:

Generic unbindModel() example¶

<?php
$this->Model->unbindModel(array('associationType' => array('associatedModelClassName')));

Now that we’ve successfully removed an association on the fly, let’s add one. Our as-of-yet unprincipled Leader needs some associated Principles. The model file for our Principle model is bare, except for the var $name statement. Let’s associate some Principles to our Leader on the fly (but only for just the following find function call):

leaders_controller.php (partial)¶

<?php
function anotherAction()
{
    //There is no Leader hasMany Principles in the leader.php model file, so
    //a find here, only fetches Leaders.
    $this->Leader->findAll();

    //Let's use bindModel() to add a new association to the Principle model:
    $this->Leader->bindModel(
        array('hasMany' => array(
                'Principle' => array(
                    'className' => 'Principle'
                )
            )
        )
    );

    //Now that we're associated correctly, we can use a single find function
    //to fetch Leaders with their associated principles:
    $this->Leader->findAll();
}

The bindModel() function can be handy for creating new assocations, but it can also be useful if you want to change the sorting or other parameters in a given association on the fly.

There you have it. The basic usage for bindModel is to encapsulate a normal association array inside an array who’s key is named after the type of assocation you are trying to create:

Generic bindModel() example¶

<?php
$this->Model->bindModel(
        array('associationName' => array(
                'associatedModelClassName' => array(
                    // normal association keys go here...
                )
            )
        )
    );

Please note that your tables will need to be keyed correctly (or association array properly configured) to bind models on the fly.