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What is a magic method? How to use it in Laravel? The following article will introduce to you how to apply PHP magic methods in Laravel. I hope it will be helpful to you!
#Laravel takes PHP to a whole new level, providing a great development experience (DX) for your next project. Therefore, some people call it "magic".
Today, I will show you a trick in Laravel,Magic Method.
It is important to understand that magic methods are not unique to Laravel and can be used in any PHP application. Laravel happens to have some of the most interesting use cases for magic methods.
Magic methods are methods available in any class declared in PHP that provide ways to implement additional functionality in the class.
Here's a good definition:
The magic method will never be called by the programmer - in fact, PHP will call the method behind the scenes. This is why they are called "magic" methods - because they are never called directly, they allow the programmer to do some very powerful things.
There are 15 magic methods in total:
class MyClass { public function __construct() {} public function __destruct() {} public function __call() {} public function __callStatic() {} public function __get() {} public function __set() {} public function __isset() {} public function __unset() {} public function __sleep() {} public function __wakeup() {} public function __toString() {} public function __invoke() {} public function __set_state() {} public function __clone() {} public function __debuginfo() {} }
If you have done some object-oriented programming with PHP, then you must know the__constructmethod, which is A magic method. So you've been using magic methods.
You also noticed that all magic methods are prefixed with "__".
Today we won’t delve into these methods, but only the interesting ones used throughout the Laravel codebase. If anyone else is interested, feel free to check out the documentation below?
PHP: Méthodes magiques - Manual
__get()
in Laravel The model is very special. They do not store attribute data as direct attributes of the class, but in theprotected $attributesattribute, which is an associative array of all the data held by the model.
Let’s look at the difference between simple PHP classes and Laravel model access properties.
firstName; // 将返回'Alice'
'Alice', ]; } $laravelUser = new LaravelUser; $laravelUser->firstName; // 依然返回'Alice'
We can see that the above PHP and Laravel classes behave exactly the same.
However, in Laravel's case, the attributes are not stored like normal PHP, but are instead concentrated in a single attribute called$attributes. We still manage to access the correct data, but how?
This is all possible because of the_getmagic method. Let's try to implement a simple example ourselves.
'Alice', ]; /** * __get 函数接收一个参数 * 它将会是你想要访问的属性名 * 在这个例子中是 $key = "firstName" */ public function __get(string $key) { return $this->attributes[$key]; } } $normalUser = new NormalUser; $normalUser->firstName; // 将会返回 'Alice'
We did it! ?
We need to note that the magic method_getwill only be called if a property with a matching name is not found in the class. This is a fallback method called when PHP cannot find the property being accessed in the class. Therefore, in the example below, the magic method_getis not called at all.
'Alice', ]; public function __get($key) { return $this->attributes[$key]; } } $normalUser = new NormalUser; /** * 由于类中存在该属性，将会返回 Bob * 所以该例子中没有调用到魔术方法__get */ $normalUser->firstName;
There's more going on behind the scenes. If you want to know more about how exactly Laravel's models use__get, you can check out the source code below.
##__set()
_setwhen the property you are trying to set is not declared in the class. Let's look again at the difference between normal PHP classes and models in Laravel.
firstName = 'Bob'; $normalUser->firstName; // Will return 'Bob'
'Alice', ]; } $laravelUser = new LaravelUser; $laravelUser->firstName = 'Bob'; $laravelUser->firstName; // Will return 'Bob' as wellAs we can see, in this example we are still trying to affect the value of
Bobwhich does not actually exist in the class but is in the attribute$ attributesmiddle. Let's try the magic method__ set
'Alice', ]; /** * The magic method __set receives the $name you want to affect the value on * and the value */ public function __set($key, $value) { $this->attributes[$key] = $value; } } $normalUser = new NormalUser; $normalUser->firstName = 'Bob'; /** * As we don't have the __get magic method define in this example for simplicity sake, * we will access the $attributes directly */ $normalUser->attributes['firstName']; // Will return 'Bob'Now we get started! We have successfully implemented the basic usage of the
__ getand__ setmagic methods in Laravel! They can do it with just a few lines of code!
__call()&__callStatic()
当调用的方法在类中找不到时，__call()会被调用。 在laravel中，该魔术方法方法使宏在 php 中成为可能。
我不会深入讨论宏的所有细节，但如果您感兴趣，这里有一篇很好的文章解释了如何在 Laravel 应用程序中使用它们?
让我们试着看看如何编写一个简单的宏示例。
fullName(); // 由于没有声明 "fullName" 方法，这将会抛出错误
使用__call，可以定义一个包含闭包函数的数组，在我们开发时可以程序化地添加到应用里。
bindTo($this, static::class), $arguments); } } $normalUser = new NormalUser; $normalUser->fullName(); // 这里会中断，因为我们既没有定义 “fullName” 宏，也没有 “fullName” 方法存在。 /** * 添加 “fullName” 宏方法 */ NormalUser::addMacro('fullName', function () { return $this->firstName.' '.$this->lastName; }); $normalUser->fullName(); // 现在，返回 “Alice Bob”
宏要比那个复杂一些，但是我们设法使用__call魔术方法来创建一个宏的简单工作版本。
除了对于静态方法，__callStatic和__call是完全一样的。
如果你打算自己再深入研究，这里有宏的特性源代码。
所以说码农们，当你第一次用 Laravel 会感觉它神奇是对的，但是通过深入查看源代码，你会理解魔法是如何在场景背后施展的。
就像现实生活中的魔法，没有道理的事情是不会发生的，在代码中就更加是了。程序运行的背后总是有着一行代码在执行，只不过需要你去发现它。
英文原文地址：https://dev.to/stvnyung/laravel-greatest-trick-revealed-magic-methods-31om
译文地址：https://learnku.com/laravel/t/40926
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