Yii2 join 6 tables + dropdown filter in grid

Question

I have the following tables/models: A, B, C, BC, D, BCD

(A:B 1:N) Connecting table D to BCD would be no problem. However I would like to filter key attributes as dropdown from A, B, C and D to find results in BCD (because in the end I need BCDid). In BCD next to BCid and Did I can store of course Aid, Bid and Cid, and it would seem to me quite an easy workaround, however I know it's totally against db normalisation. Is there another, better way (with eager loading of course)? I've now this in BCD:

public function getB() {
    return $this->hasOne(\app\models\B::className(), ['id' => 'Bid'])
                    ->via('BC');
}

and it seems to work, but it's not eager loading. And how do I get to model A? can I define it like this in BCD?:

public function getA() {
    return $this->hasOne(\app\models\A::className(), ['id' => 'Aid'])
                    ->via('BC')
                    ->via(B);
}

It doesn't really work yet.

This way it works (BCSearch):

public function search($params) {
    $query = BC::find()->joinWith('A', true)->joinWith('C', true);

Relation A in BC defined with "via". Dropdown filter also works. But I still don't know how to achieve one more level deep into db structure.

Answer 1

This way it seems to work fully:

models/BCDSearch.php

public function search($params) {
    $query = BCD::find()
            ->select([
                'BCD.id',
                'BCD.amount',
                'A.id AS A_Id',
                'A.name AS A_name',
                'B.name AS B_name',
                'B.name2 AS B_name2',
                'C.name AS C_name',
                'D.name AS D_name',
                ])
            ->leftJoin('BC', 'BC.id = BC_Id')
            ->leftJoin('B', 'B.id = B_Id')
            ->leftJoin('A', 'A.id = A_Id')
            ->leftJoin('C', 'C.id = C_Id')
            ->leftJoin('D', 'D.id = D_Id');


    $query->andFilterWhere([
        ...
        'A.id' => $this->A_Id,
        'B.name' => $this->B_name,
        'B.name2' => $this->B_name2,
        'C.name' => $this->C_name,
        'D.name' => $this->D_name,
    ]);

public function rules() {
    return [
        ...
        [[... 'A_Id', 'B_name', 'B_name2', 'C_name', 'D_name'], 'safe'],
    ];
}

models/base/BCD.php:

class BCD extends Whatever {

    public $A_Id;
    public $A_name;
    public $B_name;
    public $B_name2;
    public $C_name;
    public $D_name;

views/BCD/index.php:

GridView::widget([
    'layout' => '{summary}{pager}{items}{pager}',
    'dataProvider' => $dataProvider,
    'pager' => [
        'class' => yii\widgets\LinkPager::className(),
        'firstPageLabel' => Yii::t('app', 'First'),
        'lastPageLabel' => Yii::t('app', 'Last')],
    'filterModel' => $searchModel,
    'columns' => [
    [
        'attribute' => 'A_Id',
        'value' => 'A_name',
        'filter' => yii\helpers\ArrayHelper::map(app\models\A::find()->all(), 'id', 'name')
    ],
    [
        'attribute' => 'B_name',
        'value' => 'B_name',
        'filter' => yii\helpers\ArrayHelper::map([['id' => 'name1', 'name' => 'name1'], ['id' => 'name2', 'name' => 'name2']], 'id', 'name')
    ],
    [
        'attribute' => 'B_name2',
        'value' => 'B_name2',
        'filter' => yii\helpers\ArrayHelper::map([['id' => 'name2_1', 'name' => 'name2_1'], ['id' => 'name2_2', 'name' => 'name2_2']], 'id', 'name')
    ],
    [
        'attribute' => 'C_name',
        'value' => 'C_name',
        'filter' => yii\helpers\ArrayHelper::map(app\models\C::find()->all(), 'C_name', 'C_name')
    ],
    [
        'attribute' => 'D_name',
        'value' => 'D_name',
        'filter' => yii\helpers\ArrayHelper::map(app\models\D::find()->all(), 'D_name', 'D_name')
    ],
    'amount',
    ...

hope this helps others. It was not easy to figure out (at least for me) this basically easy solution. I don't know why but so far I couldn't find any relevant info on the web like this.