How to convert object to array in php

Converting PHP objects to arrays is one of the problems that many programmers often encounter during development. Objects and arrays are both commonly used data types in PHP, but they are different. An object is a complex data type that represents an instance of a class, while an array is an ordered collection containing multiple scalars, arrays, objects, and other elements. How to convert object to array? This article will introduce several methods.

Method 1: Use forced type conversion

You can use forced type conversion to convert an object into an array. When casting, pass the object to an array and use (array) to cast the object to an array. For example:

class Student{
    public $name;
    public $age;
}
$stu = new Student();
$stu->name = "Tom";
$stu->age = 18;
$arr = (array)$stu;
print_r($arr);

The output result is:

Array
(
    [name] => Tom
    [age] => 18
)

This method is simple and effective, but it should be noted that when performing cast type conversion, some attributes may be lost because of the forced type The conversion discards non-public properties (private and protected) in the object.

Method 2: Use the object method

If you want to convert the non-public properties in the object into an array, you can use the object method get_object_vars() to achieve this. get_object_vars() returns an array containing an object's attributes and their values. For example:

class Student{
    public $name;
    private $age;
    public function __construct($name, $age){
        $this->name = $name;
        $this->age = $age;
    }
    public function getAge(){
        return $this->age;
    }
}
$stu = new Student("Tom", 18);
$arr = get_object_vars($stu);
$arr['age'] = $stu->getAge();
print_r($arr);

The output result is:

Array
(
    [name] => Tom
    [age] => 18
)

By using the get_object_vars() method, the object can be converted into an array while retaining the private attributes in the object.

Method 3: Recursive conversion

The recursive method recursively converts objects and arrays into arrays. This method converts an object to an array in any situation, including when nested within other objects or arrays. The following is an example of recursive conversion:

class Student{
    public $name;
    public $age;
    public function __construct($name, $age){
        $this->name = $name;
        $this->age = $age;
    }
}
class Grade{
    public $name;
    public $students;
    public function __construct($name, $students){
        $this->name = $name;
        $this->students = $students;
    }
}
$stu1 = new Student("Tom", 18);
$stu2 = new Student("Jerry", 19);
$grade = new Grade("一年级", [$stu1, $stu2]);

function objectToArray($d) {
    if (is_object($d)) {
        $d = get_object_vars($d);
    }
    if (is_array($d)) {
        return array_map(__FUNCTION__, $d);
    }
    else {
        return $d;
    }
}
$arr = objectToArray($grade);
print_r($arr);

The output is:

Array
(
    [name] => 一年级
    [students] => Array
        (
            [0] => Array
                (
                    [name] => Tom
                    [age] => 18
                )

            [1] => Array
                (
                    [name] => Jerry
                    [age] => 19
                )

        )

)

As mentioned above, the recursive method is very useful for data in nested arrays and object structures.

Method 4: Use json_decode() and json_encode()

The last method is to use the json_decode() and json_encode() functions. Encode the object into a JSON format string and decode it into an array using json_decode(). This approach also works with nested arrays and objects. For example:

class Student{
    public $name;
    public $age;
    public function __construct($name, $age){
        $this->name = $name;
        $this->age = $age;
    }
}
class Grade{
    public $name;
    public $students;
    public function __construct($name, $students){
        $this->name = $name;
        $this->students = $students;
    }
}
$stu1 = new Student("Tom", 18);
$stu2 = new Student("Jerry", 19);
$grade = new Grade("一年级", [$stu1, $stu2]);

$json = json_encode($grade);
$arr = json_decode($json, true);
print_r($arr);

The output is:

Array
(
    [name] => 一年级
    [students] => Array
        (
            [0] => Array
                (
                    [name] => Tom
                    [age] => 18
                )

            [1] => Array
                (
                    [name] => Jerry
                    [age] => 19
                )

        )

)

Although json_decode() and json_encode() can easily convert PHP objects to arrays, they cannot convert private properties to arrays.

This article introduces four different methods to convert objects into arrays. In actual development, the most suitable method should be selected based on the actual situation.

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