Question

I have the database something like this

  == Invoices ==
  id
  customer_id

  == Customers ==
  id
  firstname
  lastname
  membersince

So I made relations in between both models like below.

Relation definition in the Invoices Model:

'customers'=>array(self::HAS_MANY,'Invoices','customer_id'),

Relation definition in the Customers Model

'invoices' => array(self::BELONGS_TO, 'Invoices', 'invoice_id'),

Now I want to know the relation in between both models are correct? Any suggestions are welcome.

Answer 1

No, the relation between the models is not correct.

I assume what you want here is that customers can have many invoices, but an invoice can only be owned by a single customer, as this is what your database schema implies.

Please note that in the code below I distinguish between singular and plural forms of customer and invoice to make the code logical and easy to understand.

In that case the relation definition in the Invoice model would be like this:

class Invoice extends CActiveRecord {
    public function relations() {
        return array(
            'customer' => array(self::BELONGS_TO, 'Customer', 'customer_id')
        );
    }
}

The invoice ‘belongs to’ a customer. 'Customer' indicates that the type of model we refer to is a Customer, and 'customer_id' is the name of the column in the invoices table that refers to the primary key of the customer.

The Customer model looks a bit trickier:

class Customer extends CActiveRecord {
    public function relations() {
        return array(
            'invoices' => array(self::HAS_MANY, 'Invoice', 
                               'customer_id', 'index' => 'id')
        );
    }
}

Here the relation definition indicates that a Customer can refer to many Invoice models. Notice how the rest of the relation is defined. customer_id is again the column that refers to a Customer, and 'index' => 'id' tells Yii to use the column id in the customers table as key for the relationship.

You can find more information about the relations method in the Yii documentation.