/**
 * Creates data provider instance with search query applied
 *
 * @param array $params
 *
 * @return ActiveDataProvider
 */
 public function search($params)
 {
     $query = CityModel::find();
     $dataProvider = new ActiveDataProvider(['query' => $query]);
     $this->load($params);
     if (!$this->validate()) {
         // uncomment the following line if you do not want to any records when validation fails
         // $query->where('0=1');
         return $dataProvider;
     }
     $query->andFilterWhere(['ID' => $this->ID, 'Population' => $this->Population]);
     $query->andFilterWhere(['like', 'Name', $this->Name])->andFilterWhere(['like', 'CountryCode', $this->CountryCode])->andFilterWhere(['like', 'District', $this->District]);
     return $dataProvider;
 }