Why does the AutoComplete widget return the entire list of options?

Question

JavaScript

The AutoComplete widget used in the GridView filter, when an external source is connected, returns the complete list of options, regardless of what the user enters.
If you directly specify an array in source, it works correctly. What could be wrong?
Widget connection:

'filter' => AutoComplete::widget([
                    'model' => $searchModel,
                    'attribute' => 'City',
                    'clientOptions' => [
                        'source' => Url::toRoute('columnautocomplete'),
                        
                    ],
                    'options' => ['class' => 'form-control'],
                ]),

Action in controller:

public function actionColumnautocomplete() {
        return Json::encode(Phones::find()
            ->select(['City as label'])->distinct()
            ->asArray()
            ->all());
    }

Result:

What could be the problem?

Answer 1

And what do you think it should produce if you do not impose any restrictions when selecting options on the server?

Answer 2

Add a condition.