Trait yii\db\ActiveRelationTrait

Clones internal objects.

Finds the related records for the specified primary record.

This method is invoked when a relation of an ActiveRecord is being accessed in a lazy fashion.

Sets the name of the relation that is the inverse of this relation.

For example, a customer has orders, which means the inverse of the "orders" relation is the "customer". If this property is set, the primary record(s) will be referenced through the specified relation. For example, $customer->orders[0]->customer and $customer will be the same object, and accessing the customer of an order will not trigger a new DB query.

Use this method when declaring a relation in the yii\db\ActiveRecord class, e.g. in Customer model:

public function getOrders()
{
    return $this->hasMany(Order::className(), ['customer_id' => 'id'])->inverseOf('customer');
}

This also may be used for Order model, but with caution:

public function getCustomer()
{
    return $this->hasOne(Customer::className(), ['id' => 'customer_id'])->inverseOf('orders');
}

in this case result will depend on how order(s) was loaded. Let's suppose customer has several orders. If only one order was loaded:

$orders = Order::find()->where(['id' => 1])->all();
$customerOrders = $orders[0]->customer->orders;

variable $customerOrders will contain only one order. If orders was loaded like this:

$orders = Order::find()->with('customer')->where(['customer_id' => 1])->all();
$customerOrders = $orders[0]->customer->orders;

variable $customerOrders will contain all orders of the customer.

Finds the related records and populates them into the primary models.

Specifies the relation associated with the junction table.

Use this method to specify a pivot record/table when declaring a relation in the yii\db\ActiveRecord class:

class Order extends ActiveRecord
{
   public function getOrderItems() {
       return $this->hasMany(OrderItem::className(), ['order_id' => 'id']);
   }

   public function getItems() {
       return $this->hasMany(Item::className(), ['id' => 'item_id'])
                   ->via('orderItems');
   }
}