public function addFilter($field, $label = null)
    {
        if (!$this->model->hasElement($field) instanceof \atk4\data\Field) {
            throw new \atk4\ui\Exception([
                'Unable to filter by non-existant field',
                'field'=> $field,
            ]);
        }
        $this->filters[] = ['field' => $field, 'label' => $label];
    }