ModelA.php

<?php

namespace app\models;

use Yii;
use yii\db\Expression;

/**
 * This is the model class for table "modelA".
 *
 *
 */
class Post extends \yii\db\ActiveRecord
{
    /**
     * @inheritdoc
     */
    public static function tableName()
    {
        return 'modelA';
    }

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            [['id', 'label'], 'safe'],
        ];
    }


    /**
     * @return \yii\db\ActiveQuery
     * Model A to Model B is One-to-Many
     */
    public function getModelBs()
    {
        return $this->hasMany(ModelB::className(), ['modela_id' => 'id']);
    }

    /**
     * @return \yii\db\ActiveQuery
     * Model B to Model C is Many-to-One, safely assume as One-to-one
     */
    public function getModelCs()
    {
        return $this->hasMany(ModelC::className(), ['modelb_id' => 'modelb_id'])->viaTable('modelB', ['modela_id' => 'id'])->andOnCondition(['status'=>true]);
    }


    /**
     * @return \yii\db\Query
     * ModelC to ModelD is purely one-to-one
     */
    public function getModelCD()
    {
        return static::find()->innerJoinWith('modelCs')->innerJoin('modelD','modelc.modelc_id=modeld.modelc_id')->select('modelc.*, modeld.*')->where(['modelA.id'=>$this->id])->all();
    }

}