CakePHP 2 Model relations multiple foreign Keys

Question

I have three tables:

• customers
• prices
• items

Schema example:

Customer has a Customer Number

Item can have multiple Prices belonging to different Customers

One Price belongs to one Item and one Customer

Item-Model:

class Item extends AppModel {
    public $hasOne = 'Price';
    //...
}

Price-Model:

class Price extends AppModel {

    public $belongsTo = array(
        'Item' => array(
            'className' => 'Item',
            'foreignKey' => 'id'
        )
    );

So what happens now is: One Item has 3 different Prices for 3 different Customers. I get all Items automatically (one item 3 times) but i want only the items for the currently logged in Customer (identified by customer_number, a field which appears in this tables:

• customers
• prices

Any suggestions? Thank you.

Answer 1

First up, follow CakePHP conventions: your customers table should have an id column. And your prices table should have a customer_id column, which is the foreign key to your customers table. If you need a human-friendly 'customer number', separate from the customer's id, used to identify that customer, then it can be an extra field in the customer's table, but it should not be duplicated across to the prices table.

Second, you've defined in your Item model that a Item hasOne Price. That's actually not true - an Item has many prices - one for each customer.

What you're after in this situation is a HasMany through relationship. Read that documentation - you'll end up with something like this:

// Customer.php
class Customer extends AppModel {
    public $hasMany = array(
        'Price'
    );
}

// Item.php
class Item extends AppModel {
    public $hasMany = array(
        'Price'
    );
}

// Price.php
class Price extends AppModel {
    public $belongsTo = array(
        'Customer', 'Item'
    );
}

Your prices table will need a customer_id column, and an item_id column.

Next, when returning items for the currently logged in Customer, you could do a find on your Price model, joined to your Item model, where price.customer_id equals the id of the relevant customer.