Kohana 3.1 ORM：将空模型属性值保存为0（零）而不是NULL

Question

I have two models, Product and Product_Methodology. In my product edit view I have a select form field to select one of many methodologies or none (empty first option). In my products table I have a INT(10) methodology_id property that gets saved with the id of the methodology selected from the select form field. Everything worked OK until today that I had to make an adjustment to the system in which since now selecting a methodology can be optional. So I changed the methodology_id field of the products table to allow NULL value and removed the not_empty validation rule on the model.

The problem is that now when I save the model selecting the empty option, instead of the expected NULL, I get a 0 (zero) value.

Any clue on this? Thanks a lot and let me know if it's not so clear.

Answer 1

What form input are you using for choosing the methodology? is it <select> ? If so, the value of choosen option is probably set to 0 when no methodology is choosen, and send with other form data.

In such cases I make a custom filter withing model's filters() method, to set the value to NULL (as PHP treats it) when it's empty(), something like this:

public function filters()
{
    return array(
        'methodology_id' => array(
            array('Filter::null', array(':value')),
        ),
    );
}

Where Filter is helper class with static methods. like...:

class Kohana_Filter {

    public static function null($value)
    {
        return (empty($value) ? NULL : $value);
    }

}

Hope this helps :)

Answer 2

What you should do is set the key for the None value in your select box to 0.

You should leave the not_empty rule for the field. Then you should have a rule for the field that makes sure that the value is either a legitimate value for product_methodology or zero.

I extend ORM and have the following two functions:

public function exists_or_zero(Validation $validation, $field, $model, $pk)
{
    // The exists() function is only called if the field has a non-zero value
    if ($validation[$field]) {
        $this->exists($validation, $field, $model, $pk);
    }
}

public function exists(Validation $validation, $field, $model, $pk)
{
    if ( ! ORM::factory($model, $pk)->loaded()) {
        $validation->error($field, 'exists', array($validation[$field]));
    }
}

If you were to use these functions, you're rules in the product class would look like:

public function rules()
    return array(
        'product_methodology_id' => array(
            array('not_empty'),
            array(array($this, 'exists_or_zero'), array(':validation', ':field', 'product_methodology', ':value')),
        ),
    );
}

Answer 3

Even if the submitted form field is blank it's a string with any empty value - not NULL. This gets cast as 0 when saved to an INT field (at least in mysql). To preserve a null value do something like this:

$methodology_id = (empty($methodology_id) ? NULL : $methodology_id);

Answer 4

An example of using a closure to return a NULL value if the field value is an empty string:

public function filters()
{
    return array(
        // Return a NULL value if empty string.
        'field_name' => array(
            array(function($value){
                return ($value === '') ? NULL : $value;
            }, array(':value')),
        )
    );
}