field($model, 'user_id')->widget(Select2::className(), [ 'data' => User::find()->select(['username', 'user.id']) ->joinWith('manager')->where(['manager.user_id' => null])->indexBy('user.id')->column(), 'options' => ['placeholder' => '...','class' => 'form-control'], 'pluginOptions' => [ 'allowClear' => true ], ]) ?>