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Primary Key on Model Cannot be Changed (Model with Complex PK)
  • First off, thanks for Fuel.  It's a great framework!  

    I've been banging my head with this ORM error:
    Fuel\Core\FuelException [ Error ]: Primary key on model Model_CustomValue cannot be changed.

    Here are relevant info from my models I'm having issues with:

        use Orm\Model;
        class Model_Purchase extends Model
            protected static $_has_many = array(
                'customvalues' => array(
                    'model_to' => 'Model_CustomValue',
                    'key_to' => 'purchase_id',
                    'cascade_delete' => true,
            protected static $_properties = array(
        use Orm\Model;
        class Model_CustomValue extends Model
            protected static $_table_name = 'customvalues';
            protected static $_primary_key = array('purchase_id', 'customfield_id');
            protected static $_belongs_to = array(
                'purchase' => array(
                    'key_from' => 'purchase_id',
                    'model_to' => 'Model_Purchase',
                    'key_to' => 'id',

    When trying to save the Model_Purchase with an array of Model_CustomValue objects as a property named 'customvalues' on the $purchase object, I get the "Primary key on model Model_CustomValue cannot be changed."

    I've tried putting swapping the key_from/to in the "belongs_to" on the Model_CustomValue, but to no avail.

    I'm using Fuel 1.6 (hash: 6e6d764)

    Any tips you can provide would be greatly appreciated -- donate to hosting costs, or whatever.
  • HarroHarro
    Accepted Answer
    You can not have a column which is at the same time FK and PK. Which you have on your Model_CustomValue.

    The reason for that is that when you disconnect a relation, the FK will be set to NULL, which should not happen with a PK.
  • I've added this issue to the todo list of the v2 ORM.
  • Thanks for the quick response Harro!

    So just re-stating why that's not allowed:
    Model_CustomValue uses the "purchase_id" as part of its PK as well as the FK to Model_Purchase.  And if the two Models were to be unlinked, that would lead to a null portion of the PK for Model_CustomValue -- which obviously isn't allowed.

    Can you confirm my understanding there?

  • Correct.

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