How to convert object into associative array in php

PHP is a very popular object-oriented programming language, which provides us with a large number of object operation methods. Sometimes, we will need to convert an object into an associative array so that the data can be manipulated more conveniently. In this article, we will introduce how to convert objects into associative arrays in PHP.

1. What are objects and associative arrays

Before talking about how to convert objects into associative arrays, we need to first understand what objects and associative arrays are.

An object is a data structure with properties and methods that can be created by instantiating a class. In PHP, objects are created using the keyword "new" as shown below:

class Car{
    public $brand;
    public $model;
    public function info() {
        return "This is a " . $this->brand . " " . $this->model . ".";
    }
}
$car = new Car();
$car->brand = "BMW";
$car->model = "X5";
echo $car->info();   //"This is a BMW X5."

Associative array, also known as hash table or dictionary, is a data structure that stores key-value pair data. In PHP, associative arrays can be created in the following ways:

$car = array(
    "brand" => "BMW",
    "model" => "X5"
);
echo $car["brand"];  //"BMW"

2. Convert objects into associative arrays

In PHP, we can use the get_object_vars() function to convert objects into associative arrays . This function receives an object as a parameter and returns an associative array containing all the properties and corresponding values ​​of the object. For example:

class Car{
    public $brand;
    public $model;
    public function __construct($brand, $model){
        $this->brand = $brand;
        $this->model = $model;
    }
}
$car = new Car("BMW", "X5");
$arr = get_object_vars($car);
print_r($arr);  //Array ( [brand] => BMW [model] => X5 )

As can be seen from the above code, we first define a Car class, then write the constructor, then create a Car object, pass the object as a parameter to the get_object_vars() function, and finally The function returns an associative array containing the object's properties and corresponding values.

If we only want to convert specific properties of the object into an associative array, rather than all properties, we can use the following code:

class Car{
    public $brand;
    public $model;
    public function __construct($brand, $model){
        $this->brand = $brand;
        $this->model = $model;
    }
}
$car = new Car("BMW", "X5");
$arr = array("brand" => $car->brand, "model" => $car->model);
print_r($arr);  //Array ( [brand] => BMW [model] => X5 )

In the above code, we manually specified that we want to convert it into an associative array attributes ("brand" and "model"), and then form a new associative array with the attributes and corresponding values.

3. Visibility of object attributes

In the above example, we accessed the attributes $brand and $model of the Car class. However, in actual development, many times we will set the attributes of a class as private attributes, that is, add the keyword "private" in front of the attribute, thereby restricting external access to the attribute. The following code demonstrates how to set the properties of the Car class to private properties:

class Car{
    private $brand;
    private $model;
    public function __construct($brand, $model){
        $this->brand = $brand;
        $this->model = $model;
    }
    public function getBrand(){
        return $this->brand;
    }
    public function getModel(){
        return $this->model;
    }
}
$car = new Car("BMW", "X5");
$arr = array("brand" => $car->getBrand(), "model" => $car->getModel());
print_r($arr);  //Array ( [brand] => BMW [model] => X5 )

In the above code, we first set the $brand and $model properties of the Car class to private properties and provide public Methods getBrand() and getModel() to get the values ​​of these two properties. After creating the Car object, we use these two public methods to obtain the value of the attribute, and then form a new associative array with the attribute and the corresponding value.

4. Conclusion

In this article, we introduced how to convert objects in PHP into associative arrays. We can use the get_object_vars() function to convert the object into an associative array containing attributes and corresponding values, or we can manually specify the attributes to be converted into an associative array. Of course, if the property of the class is private, we need to use public methods to get the value of the property.

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