Example of advanced relationships in Yii2

Products.php

<?php 
/**
 * @return \yii\db\ActiveQuery
 */
public function getProduct_variants()
{
    return $this->hasMany(ProductVariants::className(), ['product_id' => 'id'])->andWhere(['<>','product_variants.status', Statuses::STATUS_REMOVED]);
}

/**
 * Dynamic relationship based on relationship_type
 * @return null
 */
public function getProgram()
{
    return $this->hasOne(Programs::className(), ['id' => 'relationship_id']);
}

/**
 * @return $this
 */
public function getCourse()
{
    return $this->hasOne(Courses::className(),['id' => 'course_id'])
        ->viaTable(Programs::tableName(), ['id' => 'relationship_id']);
}

/**
 * @return $this
 */
public function getLocation()
{
    return $this->hasOne(Locations::className(),['id' => 'location_id'])
        ->viaTable(Programs::tableName(), ['id' => 'relationship_id']);
}

ProductsAPIController.php

<?php 
$programs = Products::find()->courses()->asArray()->all();

ProductsQuery.php

<?php
//Products table
/**
 * @return $this
 */
public function courses() {

    return $this->abc()
        ->with(['product_variants'])
        ->joinWith(['product_type'])
        ->andWhere(['product_types.slug' => Products::SCENARIO_COURSE])
        ->joinWith(['program'=> function($q) {
            $q->from('programs p');
        }])
        ->joinWith(['location'=> function($q) {
            $q->from('locations l');
        }])
        ->joinWith(['course' => function($q) {
            $q->from('courses c');
    }]);
}