About late static binding in Laravel

This article mainly introduces a brief discussion of a late static binding in Laravel. The content is quite good. I will share it with you now and give it as a reference.

Regarding PHP's new static delayed static binding, or late static binding, I encountered a usage problem in Laravel. As follows, when calling the Model in Laravel to add new data, first add a method to the Model to obtain the sub-table:

protected function addToMessage($msgType, $userID, $commentID, $replyCommentID, $replyUserID, $gameID)
{
  if (!$userID) {
    return false;
  }
 
  $table = 't_message_' . hashID($userID, 100);
  $this->message->setTable($table)->create([
    'msg_type'     => $msgType,
    'user_id'     => $userID,
    'comment_id'    => $commentID,
    'reply_comment_id' => $replyCommentID,
    'reply_user_id'  => $replyUserID,
    'game_id'     => $gameID,
    'is_read'     => 0,
    'created_at'    => date('Y-m-d H:i:s'),
  ]);
  return true;
}

The setTable method here is in the Model The method of obtaining the sub-table defined in:

public function setTable($table)
{
  $this->table = $table;
  return $this;
}

It is found from the error log that $this->table does not take effect, but the create method is actually called. When the table name was printed before, it was the expected value. Why is $this->table not reset when the create method is called here?

Here $this->message is a model class that inherits the Model class, where the create method:

public static function create(array $attributes = [])
{
  $model = new static($attributes);
 
  $model->save();
 
  return $model;
}

is located in vendor\laravel\ framework\src\Illuminate\Database\Eloquent\Model.php Line 557.

Because the Model class of the Laravel framework is an abstract type, the abstract class in PHP can be instantiated using new static late static binding. , and $model = new static($attributes) in the create method is actually re-instantiated and returned, and the caller Model class does not define the table attribute, so $this->table has no value at this time.

The solution is to use the save method, as shown in the figure. In fact, the create method also calls the save method.

Experiment

An abstract class A has a create method, which is instantiated and returned through delayed static binding. Class B inherits A, and the name attribute of the parent class is modified in the test method.

<?php
 
abstract class A
{
  protected $name = "tanteng";
 
  public static function create()
  {
    return new static();
  }
}
 
class B extends A
{
  //protected $name = &#39;纸牌屋弗兰克&#39;;
 
  public function test()
  {
    $this->name = "Tony Tan";
    return $this;
  }
}
 
$obj1 = (new B)->test();
$obj2 = (new B)->test()->create();
var_dump($obj1);
var_dump($obj2);

The results show that both instances $obj1 and $obj2 are instances of B. The attribute name has changed by calling the test method, but after calling the create method, The name attribute has not changed. This is the scene encountered in Lavarel mentioned in this article. (If the annotation is turned on here, the printed name is the rewritten value)

If the abstract class A is changed to a normal class, and new static is changed to new self for instantiation, the result will be different, the printed The attribute name is an attribute of the respective class.

The above is the entire content of this article. I hope it will be helpful to everyone's study. For more related content, please pay attention to the PHP Chinese website!

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