[Wiki] Yii2 GridView Sorting and Searching with a Junction Table Column(Many to Many Relationship)

CREATE TABLE IF NOT EXISTS `tblgroups` (
  `id` int(11) NOT NULL,
  `groupname` varchar(150) NOT NULL,
  `status` tinyint(1) NOT NULL DEFAULT '1' COMMENT '1=Acitve,2=Inactive',
  `date` datetime NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

CREATE TABLE IF NOT EXISTS `tblcontacts` (
  `id` int(11) NOT NULL,
  `firstname` varchar(100) NOT NULL,
  `lastname` varchar(100) NOT NULL,
  `company` varchar(100) NOT NULL,
  `address` text NOT NULL,
  `phone` varchar(50) NOT NULL,
  `mobile` varchar(50) NOT NULL,
  `fax` varchar(50) NOT NULL,
  `pemail` varchar(100) NOT NULL,
  `semail` varchar(100) NOT NULL,
  `country` varchar(55) NOT NULL,
  `websiteurl` varchar(100) NOT NULL,
  `gender` tinyint(4) NOT NULL COMMENT '1=male,2=female,3=shemale',
  `birthday` varchar(10) NOT NULL,
  `status` tinyint(4) NOT NULL DEFAULT '1' COMMENT '1=Active,2=Inactive',
  `sentstatus` tinyint(4) NOT NULL DEFAULT '1' COMMENT '1=sent,2=not sent',
  `addeddate` datetime NOT NULL,
  `updateddate` datetime NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=latin1;

CREATE TABLE IF NOT EXISTS `tblcontactsgroups` (
  `id` int(11) NOT NULL,
  `contact_id` int(11) NOT NULL,
  `group_id` int(11) NOT NULL,
  `dateadded` datetime NOT NULL
) ENGINE=MyISAM AUTO_INCREMENT=20085 DEFAULT CHARSET=latin1;

public function getGroups() {
        return $this->hasMany(Groups::className(), ['id' => 'group_id'])->viaTable('tblcontactsgroups', ['contact_id' => 'id']);
    }

public function getContacts() {
        return $this->hasMany(Contacts::className(), ['id' => 'contact_id'])->viaTable('tblcontactsgroups', ['group_id' => 'id']);
    }

public $groupname

public function rules() {
        return [
            [['id', 'gender', 'status', 'sentstatus'], 'integer'],
            [['firstname', 'lastname', 'company', 'address','groupname', 'phone', 'mobile', 'fax', 'pemail', 'semail', 'country', 'websiteurl', 'birthday', 'addeddate', 'updateddate'], 'safe'],
        ];
    }

public function search($params) {
        $query = Contacts::find()->innerJoinWith('groups', true); //important to note
 
        $dataProvider = new ActiveDataProvider([
            'query' => $query,
            'sort' => ['attributes' => ['firstname', 'lastname', 'groupname', 'email', 'pemail']]
        ]);
 
        $this->load($params);
 
        if (!$this->validate()) {
            // uncomment the following line if you do not want to return any records when validation fails
            // $query->where('0=1');
            return $dataProvider;
        }
 
        // grid filtering conditions
        $query->andFilterWhere([
            'id' => $this->id,
            'gender' => $this->gender,
            'status' => $this->status,
            'sentstatus' => $this->sentstatus,
            'addeddate' => $this->addeddate,
            'updateddate' => $this->updateddate,
        ]);
 
        $query->andFilterWhere(['like', 'firstname', $this->firstname])
                ->andFilterWhere(['like', 'lastname', $this->lastname])
                ->andFilterWhere(['like', 'company', $this->company])
                ->andFilterWhere(['like', 'address', $this->address])
                ->andFilterWhere(['like', 'phone', $this->phone])
                ->andFilterWhere(['like', 'mobile', $this->mobile])
                ->andFilterWhere(['like', 'fax', $this->fax])
                ->andFilterWhere(['like', 'pemail', $this->pemail])
                ->andFilterWhere(['like', 'semail', $this->semail])
                ->andFilterWhere(['like', 'country', $this->country])
                ->andFilterWhere(['like', 'websiteurl', $this->websiteurl])
                ->andFilterWhere(['like', 'birthday', $this->birthday])
                ->andFilterWhere(['like', 'groupname', $this->groupname]); //include this related table property here
 
        return $dataProvider;
    }

GridView::widget([
        'dataProvider' => $dataProvider,
        'filterModel' => $searchModel,
        'columns' => [
            ['class' => 'yii\grid\SerialColumn'],
            [
                'label' => 'First Name',
                'attribute' => 'firstname',
            ],
            [
                'label' => 'Last Name',
                'attribute' => 'lastname',
            ],
            //  'company',
            // 'address:ntext',
            // 'phone',
            // 'mobile',
            // 'fax',
    //Following is the related column from the groups table
            [
                'label' => 'Groups',
                'format' => 'ntext',
                'attribute'=>'groupname',
                'value' => function($model) {
                    foreach ($model->groups as $group) {
                        $groupNames[] = $group->groupname;
                    }
                    return implode("\n", $groupNames);
                },
            ],
            [
                'label' => 'Primary Email',
                'attribute' => 'pemail',
            ],
            // 'semail:email',
            // 'country',
            // 'websiteurl:url',
            // 'gender',
            // 'birthday',
            // 'status',
            // 'sentstatus',
            // 'addeddate',
            // 'updateddate',
            ['class' => 'yii\grid\ActionColumn'],
        ],
    ]);
    ?>