yii2：在link（）之前validate（）

Question

docs says: The model with the foreign key will be saved into database without performing validation.

But if I want to use validation before

$order->link('items', $item);

is enough?

if ($order->validate() && $item->validate())
{
    $order->link('items', $item);
} else {
//do something
}

Or there is other solution?

Answer 1

There is a good example in docs :

$customer = Customer::findOne(123);
$order = new Order();
$order->subtotal = 100;

// without link()
$order->customer_id = $customer->id;
$order->save();

That has been reduced to this when using the link method instead:

$customer = Customer::findOne(123);
$order = new Order();
$order->subtotal = 100;

// with link()
$order->link('customer', $customer);

The two things to notice here are:

1. The 2 models $customer and $order are sharing a one_to_many relationship.
2. The $customer object was retrieved from DB which means it already exist and have a valid primary key that the link method need to use in order to relate the 2 models.

Which explains that little note in the same docs:

Note: You cannot link two newly created Active Record instances.

In that example we are only going to save $order object. So yes it make sense to validate it first the way you did but not $customer as it already exist and we will not change anything on it:

if ($order->validate()) {
  $order->link('customer', $customer);
} else {
//do something
}

Now back to your example. If I'm not wrong the commun relationship we are used to see between an order and their items is usually a many_to_many relation. And that is a totally different case as both models should already exist with not null primary key values. Otherwise an exception will be thrown as you can see in its source code :

if ($relation->via !== null) { // -> many_to_many relation
    if ($this->getIsNewRecord() || $model->getIsNewRecord()) {
        throw new InvalidCallException('Unable to link models: the models being linked cannot be newly created.');
    }

Linking both models in this case is the process of insertion of a new row in their related junction table where you can also pass additional column values ( like maybe quantity,total_price,.. ) within the link $extraColumns propery and if it fails an exception will be thrown.

So in that particular case it make no sense to validate two already existing models. You should care about validation only if you have more data to insert in a junction table and that is usually a different model than the two you are linking.

I think the key rule when using the link method is to figure out (dependly on the relationship type between the two models to be linked) where modifications should be made in the database and perform your validations based on it.