如何在ORM中制作过滤器？

Question

For example my Model has method get_objects, I am searching them by following source:

class Model_Object extends ORM {

public function get_objects($filters = array())
{

        if (!empty($filters['Role']))
            $role = $filters['Role'];
          else
        $role = NULL;


        $objects = ORM::factory('object')
                         ->where('RoleId','=',$role)
                         ->find_all();

       return $objects;
}

So that code will work only when the filter exists, when there's no values in filter I'll not have any records instead of all (I want all records then), how to make it better?

Answer 1

It sounds like you want to make the ORM where call dependent on the relevant filter key being present. The following code should do what you're looking for, it works for me, does it do what you want?

It would be neater if it didn't allow for the key-name/field-name distinction (Role vs. RoleId).

application/classes/Model/Object:

class Model_Object extends ORM {

    // Map from filter key names to model field names
    protected static $_filter_map = array(
        'Role' => 'RoleId',
        // ...
    );

    public static function get_objects($filters = array())
    {

        $objects = ORM::factory('object');

        foreach($filters as $key => $value)
        {
            if ($field = Arr::get(self::$_filter_map, $key))
            {
                $operator = (is_array($value)) ? 'IN' : '=';
                $objects->where($field, $operator, $value);
            } else {
                throw new Kohana_Exception(
                    'Unknown filter key :key',
                    array(':key' => $key)
                );
            }
        }

        return $objects->find_all();
    }
}

Some examples, first all objects:

Model_Object::get_objects( array() );

All objects with RoleId equal to 2:

Model_Object::get_objects( array('Role' => 2) );

All objects with role_id in (2,3,5) AND user_id = 1:

Model_Object::get_objects( array(
    'Role' => array(2,3,5),
    'User' => 1
) );

Note that this last one requires you to have:

protected static $_filter_map = array(
    'Role' => 'role_id',
    'User' => 'user_id', // where `user_id` is a db field name
    // ...
);

OR to change/simplify the get_objects function to

$objects = ORM::factory('object');

foreach($filters as $key => $value)
{
    $field = Arr::get(self::$_filter_map, $key, $key);
    $operator = is_array($value) ? 'IN' : '=';
    $objects->where($field, $operator, $value);
}

return $objects->find_all();