How to convert empty array to json object in php

php method to convert empty array to json object: 1. Use "JSON_FORCE_OBJECT" to convert json object; 2. Use data type conversion to convert empty array to json object; 3. Use ArrayObject to convert empty array to json object.

The operating environment of this article: Windows 7 system, PHP version 7.1, DELL G3 computer

PHP json_encode converts empty arrays into objects

Problem Description:

php provides interfaces to the client, such as PC, Android, ios, etc. If data in json format is returned, when the returned data is Array, and the key is a string, jsonObject will be returned after jsonization. However, if it is an empty array, jsonArray may be returned. Inconsistency in the data structure causes the end to parse json to fail.

For example:

$arr  = [
     'id'  => 123.,
     'name'  =>  'andrew' ,
];
 
$jsonRet  = json_encode( $arr );
 
print_r( $jsonRet );

Output:

{
  "id": 123,
  "name": "andrew"
}

But if it is:

$arr = [];
$jsonRet = json_encode($arr);
print_r($jsonRet);

Output:

[
  
]

How to when the array is empty Is it also JsonObject?

Method 1:

Use JSON_FORCE_OBJECT

$arr = [];
$jsonRet = json_encode($arr, JSON_FORCE_OBJECT);
print_r($jsonRet);

This method has a drawback, eg:

$arr = [
    'jsonArray' => [
        '21', '12', '13'
    ],
    'jsonObject' => []
];
$jsonRet = json_encode($arr,JSON_FORCE_OBJECT);
print_r($jsonRet);

Output:

{
  "jsonArray": {
    "0": "21",
    "1": "12",
    "2": "13"
  },
  "jsonObject": {
    
  }
}

The original jsonArray has also been jsonObjectified, and local changes cannot affect the global

Method 2

Use data type conversion

$bar = array();  
$foo = (object)$bar;  
echo json_encode($foo);

Method three (recommended)

Use ArrayObject

$arr = [
    'jsonArray' => [
        '21', '12', '13'
    ],
    'jsonObject' => new \ArrayObject()
];
$jsonRet = json_encode($arr);
print_r($jsonRet);

Output:

{
  "jsonArray": [
    "21",
    "12",
    "13"
  ],
  "jsonObject": {
    
  }
}

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