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I have a problem with this behavior.

My model (simplified) is this one:

class Proyecto extends AppModel {
$belongsTo=array('User' => array('className' => 'User','foreignKey' => 'user_id','conditions' => '','fields' => '','order' => '');
}

class Potencia extends Proyecto {
var $name = 'Potencia';
var $validate = array(
'proyecto_id' => array('numeric')
);

var $actsAs = array(
'Inheritable'=> array('method'=>'CTI') /*Significa: Utilitza el Behavior amb em metode Class Table Inheritance (CTI)*/
);
}

When I find over Porencia, I have an SQL error (SQL Error: 1054: Unknown column 'Armonico.user_id' in 'on clause').
I think cake searches the users as if the subclass where directly linked with the users model.
Let me know if I am wrong or it is a bug.

Thank you!

I really like this approach but how come CTI does not use a type field? What if I wanted to list all Assets and sort them by type?

I've modified the behavior to allow for a "type" field in CTI

Go to saveParentModel method and change $parentData to the following:

<?php
$parentData = array(
   $model->parent->primaryKey => $model->id,
   $model->inheritanceField => $model->alias
);?>

You'll also need to create the type field in the table of your superclass.

Also, if you have deeper inheritance there will be a problem with setting values to the main class. Here's an example:

Person > Users > Administrators

Let's say "Person" has the field "first_name". If you want to set that field through the Administrator class, it won't work. In order to make it work you have to go to the saveParentModel and remove the if statement
if (in_array($key, $fields)) {
This prevents any field that is not in the immediate parent class from being included. $fields is the list of fields from $model->parent->schema() ... and in this case, if we're adding an administrator, the parent model is User. The schema() method, therefore, does not include the fields from Person, it only includes the fields from User. So if you have the data 'Administrator.first_name' it won't be added because "first_name" is a field from the Person model.

By removing the if statement, you're getting rid of the restrictions on what fields can be passed. So the foreach loop should look like this

In the foreach loop it should look like this:

<?php
foreach ($model->data[$model->alias] as $key => $value) {
   $parentData[$key] = $value;
}
?>

If we can some how get $model->parent->schema() to get all the fields, even those included in that model's parents... then this wouldn't be required, but at the moment I don't see how that can be done.

Thanks for this post. It has brought the issue of "object-relational impedance mismatch" to my knowledge. This has been troubling me for some time now, so it's good to be able to put a name to it! So many thanks.

can you confirm if deep inheritance saving works after such modification? as well as how does deep inheritance behaves for the whole CRUD operation.
Create/Update/Delete works, but not flawlessly.

Here's the example I'm working with.
Node > Contacts > User

User is a contact; contact is a node.

When I save a user the callback methods for all models are executed, but if I define a callback method in user (ex: beforeValidates()), ideally the parent functions should only be called if I explicitly call parent::beforeValidate(). I guess because they're callbacks they will be called for all models involved in saving/retrieving data, but it doesn't seem like expected behaviour since I am really just saving a User and if User::beforeValidate() doesn't call parent::beforeValidate() I don't think it should be executed.

Deeper inheritance doesn't seem to work with reading data. In my Node > Contact > User example, when I read a User record only the Contact fields are included. Node is not included in the association nor are the fields in the results array.

Hope that helps

Originally said in this comment that it didn't work well with TreeBehavior, but it does work well with it.

For some reason the afterSave method of the behavior is set to only allow saving of the parent model if a new record is being created.

Here is the code:

if ($created && $method == 'CTI') {
   return $this->saveParentModel($model);
}

I'm not sure why this was initially set like this, but if I update the child model, I would also want the parent model fields to reflect the changes. So in order to "fix" this, get rid of the $created clause in the if statement.

Say Digit extends Widget and Widget belongs to Doodles.

First off, I receive an join error because doodle_id does not exist on Digit (but it does on Widget), so I overwrote the $belongsTo in Digit with:

Model Class:

<?php 
class Digit extends Widget {
   var $name = 'Digit';
   var $actsAs = array(
       'Inheritable' => array('method' => 'CTI')
   );
   var $belongsTo = array();
}
?>
In order to still deep fetch the Doodles, I hard-coded recursive to 2 in the classTableBeforeFind method (Note I tried setting the recursive before the find but it was wiped out).

The method should look something like this after:


extract($this->settings[$model->alias]);
$bind = array('belongsTo' => array(
   "{$model->parent->alias}" => array(
       'className' => $model->parent->alias, 'foreignKey' => "{$model->primaryKey}"
   )
));
$model->bindModel($bind);
$query['recursive'] = 2;


Now this might be complete crap, but it works. Does this spark any ideas for a better implementation?

I mean, there's many ways of storing a class hierarchy in a relational database using different tables. Even the article you provided doesn't clear out how, and you don't specify what those id really are.

So I don't really understand wich way you chose, so first, I'm gonna say you should add some examples using find and save and what do they return.

One way I need to, is that the superclass doesn't actually have an associated table. I can go around that, but still... seems imposible like this.
Also, the most common way I see and used this in object oriented languages is, the superclass has a table wichs primary key is generated autoincremental/serial, then subclasses primary key is in fact a foreign key of the superclass. You didn't put much into the tables you posted, so I can't know how you intended it to work, but certainly is not this way. Or if it is, it's just not working how it should.
You can have an independent primary key in each table, but then you're gonna have to use a foreign key to the superclass, and that would make the database not normalized, since it depends on your primary key.

So, how? Wich way is it? I read someone added a 'type' field somewhere, wich is not needed and probably shouldn't be used.

What I also see unexplained is the type field in STI... is it mandatory, it has to be named 'type' and needs to be string?

Props for the initiative, I hope this goes far, but as much as this is a decent aproach, I believe it should be done in AppModel, well done, by core CakePHP developers too.

I have had trouble implementing this behavior (CTI method) for models that have associations. My example is:

Model Class:

<?php 
class Asset extends AppModel {
    var $belongsTo = array('User');
}
?>

Model Class:

<?php 
class Image extends Asset {
    var $actsAs = array('Inheritable' => array('method' => 'CTI'));
}
?>

When I try:

Controller Class:

<?php 
$images = $this->Image->find('all');
?>
I get an error because Cake is looking for the user_id field in my Image table, however I want this field to live in the Assets table since all assets will share this property.

Any tips?

@zach: in the base class (Asset) you have a belongsTo variable. You need to set this to an empty array in the classes that extend the base class (Asset).

In other words the Image class should have the line:
var belongsTo = array();

Thanks Rob!

Thank you Rob, that got rid of my error!

My next question is about the implementation, specifically, as Franco mentioned above, most CTI implementations give a primary key to the super class and then save that same key as a foreign key in the subclass, for example


assets table
-----
id: 1
title: my fist picture
-----
id: 2
title: my link
-----
id: 3
title: my second picture
-----


images table
-----
id: 1
filename: file1.jpg
-----
id: 3
filename: file2.jpg
-----



links table
-----
id: 2
url: http://mypage.com
-----

I assumed that I would set only the assets table's id field to auto increment and the images and links table's ids would be set to the asset table's primary key automatically. Thus the images and assets tables would not have an auto increment field.

I have also tried adding a field 'asset_id' to the subclasses' tables, but the foreign key to the asset table is not being set.

How can I store data for more than one subclass if the superclass' table doesn't have the primary key for all subclasses and there is no foreign key within the subclasses?

Is this something that I need to handle manually or am I missing something?

@zach you need a varchar field field named 'type' in the base table. This way your base class knows which row belongs to which subclass.

Hi Rob,

I have the 'type' field and it is working perfectly... What I am looking for is an answer as to how the superclass record is joined with the correct subclass record.

It seems that the implementation should be saving the primary id of the superclass record (the Assets.id field in my example) in the related subclass record (Image.id or Image.asset_id).

Otherwise the Asset.title and Image.filename records for a particular Image will have no way to be matched up.

My initial thinking was that the Image.id field would be set automatically to match its related Asset.id. This means I would set only the Asset.id field to auto increment, with its subclasses ids being set automatically by the behavior to the same value...

I don't see this happening automatically, so I am wondering if I missed something or if I need to handle the subclass id setting on my own?

I'm pretty much a beginner when it comes to CakePHP, and I can't get the subclass behavior to work.

My simplified models look like this:

Model Class:

<?php 
class Person extends AppModel{
    var $name = 'Person'
}
?>

Model Class:

<?php 
App::import('Model', 'Person');
class Child extends Person{
    var $actsAs = array(
        'Inheritable' => array(
            'method' => 'CTI'
        )
    );
}
?>
When i do find('all'), the system gives me 'undefined index' notices on everything from the subclass table, and the query looks like this:
SELECT Child.id, Child.info, Child.created, Child.modified
FROM persons AS Child
Basically, it doesn't join with the Child table. What am I doing wrong?

Edit: typo

I think even though you named the class "Supported", you still have to extend the actual class Person.

There was some copy-paste problem there, and I displayed the wrong code here in the post. Now it's correct, and displays as it is used in the application, but the problem still exists.

Some experimenting with deleting the Inheritable Behavior files makes me think that I might have placed the extracted files in the wrong folder. As the article tells me to, I downloaded the rar-file and extracted it to the root of my cakePHP installation, so that it now contains four folders: app, cake, vendors and inheritable_behavior. Is this right?