A brief analysis of Laravel's late static binding

This article mainly introduces a brief discussion of a late static binding in Laravel, and shares it with everyone as a reference. I hope to be helpful.

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 the method defined in the Model to obtain the sub-table:

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

I found from the error log that $this->table did not take effect, but in fact when the table name was printed before calling the create method, it was the expected value. Why was $this->table not being used when the create method was called here? What about reset?

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 in the create method $model = new static($ attributes) is actually re-instantiated and returned, and the caller's 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 of $obj1 and $obj2 are instances of B. The attribute name changes when the test method is called, but the name attribute does not change after the create method is called. This is the scene encountered in Lavarel mentioned in this article. (If comments are 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.

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