Yii2 get data from many to many relation in gridview and apply filter

Question

i'm developing a web application with Yii2 framework, and i'm facing a problem right now. I want to display the data from a many-to-many relation in a gridview and be able to filter from those fields later on.

I've read the official documentation here , some stackoverflow post like this and other resources but can't seem to get it to work. I have 3 tables: actividad , plan_actividad and circulo_icare , actividad is related to plan_actividad and circulo_icare is also related to it ( plan_actividad is the junction table). So i have defined the following relations in my Actividad model:

class Actividad extends \yii\db\ActiveRecord 
{
   .... 

public function getPlanActividad()
{
    return $this->hasMany(PlanActividad::classname(), ['act_id' => 'act_id']);
}

public function getCirculo()
{
    return $this->hasMany(CirculoIcare::classname(), ['cirica_id' => 'act_id'])->via('planActividad');
}

...
}

The in my view index.php i'm trying to show the values in a gridview like this:

<?= GridView::widget([
    'dataProvider' => $dataProvider,
    // 'filterModel' => $searchModel,
    'columns' => [
        ['class' => 'yii\grid\SerialColumn'],

        // 'act_id',
        ['attribute' => 'Codigo Evento', 'value' => 'act_numorden'],
        ['attribute' => 'Nombre Evento', 'value' => 'act_nombre'],
        ['attribute' => 'Fecha Evento', 'value' => 'act_fecha'],
        ['attribute' => 'Locacion', 'value' => 'locacion.loc_nombre'],
        [
        'attribute' => 'Circulo',
        'value' => 'circulo.cirica_nombre',

        ],
        ['attribute' => 'Circulo id',
         'value' => 'planActividad.cirica_id',
        ],
        // 'act_horaini',
        // 'act_horafin',
        // 'act_idencuesta',
        // 'act_vigencia:boolean',
        // 'loc_id',

        ['class' => 'yii\grid\ActionColumn'],
    ],
]); ?>

The problem is, i can't get any values to show with the circulo relation, it always shows (not set) . If i change hasMany in getPlanActividad() with hasOne() then it shows some values (only 2 of 11 it should, based on the cirica_id that exist on plan_actividad table) but these are not correct anyway. I know that i can filter for those fields later on in search view but i don't really understand why the relations doesn't work as i expected.

Any help would be greatly appreciated, let me know if more info is needed and thank you in advance.

Answer 1

Answering my own question (credits to softark from the yii official forums).

In order for the relation to work as expected, I had to change:

public function getCirculos()
{
     return $this->hasMany(CirculoIcare::classname(), ['cirica_id' => 'act_id'])->via('planActividad');
}

to

public function getCirculos()
{
     return $this->hasMany(CirculoIcare::classname(), ['cirica_id' => 'cirica_id'])->via('planActividad');
}

and use a callback function in the gridview to display the correct values, since a hasMany relation gives an array of models and not a single model. So I modified the gridview code to:

<?= GridView::widget([
    'dataProvider' => $dataProvider,
    // 'filterModel' => $searchModel,
    'columns' => [
        ['class' => 'yii\grid\SerialColumn'],

        ...

        ['attribute' => 'circulo',
         'value' => function($model){
            $items = [];
            foreach($model->circulos as $circulo){
                $items[] = $circulo->cirica_nombre;
            }
            return implode(', ', $items);
         }],

        ...

        ['class' => 'yii\grid\ActionColumn'],
    ],
]); ?>

This gives the expected results. You can then apply filter by the relation fields easily by adapting the search model.