Yii2 extending Gii CRUD with many-to-many form elements

Question

I have the following 3 tables:

Rule
-id
-name

CombinedRule
-id
-name

RuleCombineMapping
-id_rule
-id_combine

I generated a CRUD for Rule and for the CombinedRule table. Inside the CombinedRule model class I created a mapping the class looks like the following:

<?php

namespace app\models;

use Yii;

/**
 * This is the model class for table "combinedrule".
 *
 * @property integer $id
 * @property string $name
 */
class CombinedRule extends \yii\db\ActiveRecord {

    /**
     * @inheritdoc
     */
    public static function tableName() {
        return 'combinedrule';
    }

    /**
     * @inheritdoc
     */
    public function rules() {
        return [
            [['name'], 'string', 'max' => 255],
            [['name'], 'unique']
        ];
    }

    /**
     * @inheritdoc
     */
    public function attributeLabels() {
        return [
            'id' => 'ID',
            'name' => 'Name',
        ];
    }

    public function getRules() {
        return $this->hasMany(Rule::className(), ['id' => 'id_rule'])
                        ->viaTable(RuleCombineMapping::tableName(), ['id_combine' => 'id']);
    }

}

Without success I tried to access the rules of a certain CombinedRule by using the following lines inside the CombinedRuleController.

$t = CombinedRule::find($id);
var_dump($t->rules);

The results is always a 'Unknown Property' exception.

Now I want to view/update/read/delete not only Rules and CombinedRules but also the relation between those two.

I know this is possible in other frameworks using doctrine and I also know how to do it manually first fetching the relation and then adding it to a list.

Now does anybody has a working example how to map this tables using a similar established data structure and also integrate it as easy as possible in the Gii CRUD using its front-end models, views and forms?

Answer 1

I've tried it now myself and it worked for me. That is, var_dump($model->rules); in view file gave me an array with Rule objects as expected.

Here are my gii generated files. I have removed comments, attributeLabels(), rules() methods from model classes and action methods and behaviours() from the controller class. So this is the essential code that is required to make $model->rules working:

Rule

class Rule extends \yii\db\ActiveRecord {
    public static function tableName() {
        return 'rule';
    }
}

CombinedRule

class CombinedRule extends \yii\db\ActiveRecord {
    public static function tableName() {
        return 'combined_rule';
    }

    // Added this manually, this does not come from gii!
    // It is the single code that I've added.
    public function getRules() {
        return $this->hasMany(Rule::className(), ['id' => 'id_rule'])
            ->viaTable(RuleCombineMapping::tableName(), ['id_combine' => 'id']);
    }
}

RuleCombineMapping

Gii has also generated two methods getIdCombine() and getIdRule() which are also not essential for the issue.

class RuleCombineMapping extends \yii\db\ActiveRecord {
    public static function tableName() {
        return 'rule_combine_mapping';
    }
}

CombinedRuleController

class CombinedRuleController extends Controller {

    public function actionView($id) {
        return $this->render('view', [
            'model' => $this->findModel($id),
        ]);
    }

    protected function findModel($id) {
        if (($model = CombinedRule::findOne($id)) !== null) {
            return $model;
        } else {
            throw new NotFoundHttpException('The requested page does not exist.');
        }
    }
}

views/combined-rule/view.php

Just added var_dump($model->rules);. Other is gii generated code.

use yii\helpers\Html;
use yii\widgets\DetailView;

$this->title = $model->title;
$this->params['breadcrumbs'][] = ['label' => 'Combined Rules', 'url' => ['index']];
$this->params['breadcrumbs'][] = $this->title;
?>
<div class="combined-rule-view">

    <h1><?= Html::encode($this->title) ?></h1>

    <p>
        <?= Html::a('Update', ['update', 'id' => $model->id], ['class' => 'btn btn-primary']) ?>
        <?= Html::a('Delete', ['delete', 'id' => $model->id], [
            'class' => 'btn btn-danger',
            'data' => [
                'confirm' => 'Are you sure you want to delete this item?',
                'method' => 'post',
            ],
        ]) ?>
    </p>

    <?= DetailView::widget([
        'model' => $model,
        'attributes' => ['id', 'title'],
    ]) ?>

    <?php
        // And here it is: an array of Rule objects!!!!! 
        var_dump($model->rules);
    ?>
</div>