How do I apply a CDataColumn filter to my CGridView so it displays only rows with a null-value? - yii

Question

I have a model with a boolean value, generated from a table like this:
CREATE TABLE receivable (
...
is_paid INTEGER DEFAULT NULL,
...
)
You should only take notice of the possible NULL value.
I have a gii-generated Receivable.php-model and a simple CGridView, like this:
$dataProvider = $model->search();
$dataProvider->pagination = ['pageSize'=>20];
$this->widget('zii.widgets.grid.CGridView', array(
'dataProvider'=>$dataProvider,
'filter'=>$model,
'columns'=>array(
'id',
[
'name'=>'is_paid',
'type'=>'raw',
'value'=>'($data->is_paid==1)?"PAID":"";',
'filter'=>['1'=>'PAID', '0'=>'0']
],
'someothercolumn',
['class'=>'CButtonColumn']
),
);
It should make sense so far? It does work fine I must say, with just one tiny problem - I want to allow filtering on null values as well!
'filter'=>['1'=>'PAID', '0'=>'0', null=>'null'] // This shows all records.
'filter'=>['1'=>'PAID', '0'=>'0', ''=>'null'] // This also shows all records.
'filter'=>['1'=>'PAID', '<>1'=>'null or zero'] // This shows 0-records only.
Well, now I'm at a loss. Is there any way I can use the CDataColumn.filter to allow the user to filter on null values? (Only display rows where 'is_paid'==null)
Edit: Values can be 1,0 or NULL, but the filter can only be applied for 1 or 0 (or show everything). How can I let the user display rows with null-values only?
Any help is much appreciated!

Answer 1

this is one way you can do it
1.'filter' => array('0' => Yii::t('app', 'No'), '1' => Yii::t('app', 'Yes')),
or something like this
2.is_paid:boolean
or something like this
3.'filter' => CHtml::listData(UserRegistry::model()->findAll(), 'id_user_registry', 'firstname' ),
In the above example i have the values in a db table
or something like this
4.'filter' => Lookup::items('option'),
and for the above example in the model you would have something like this
4. public static function items($type, $code)
{
if(!isset(self::$_items[$type]))
self::loadItems($type);
return isset(self::$_items[$type][$code]) ? self::$_items[$type][$code] : false;
}
private static function loadItems($type)
{
self::$_items[$type]=array();
$models=self::model()->findAll(array(
'condition'=>'type=:type',
'params'=>array(':type'=>$type),
//'order'=>'position',
));
foreach($models as $model)
self::$_items[$type][$model->code]=$model->name;
}