How to convert object array to json format in php

In web development, it is often necessary to transmit an object array to the front end for processing, and this data usually needs to be transmitted in json format. Many languages ​​​​in util provide tools to convert objects into json format, and php is no exception. This article will introduce in detail the method of converting object array to json format in php.

1. Use of json_encode() function

PHP provides the json_encode() function to convert the object array into json format. The method of using this function is as follows:

Sample code:

<?php $person = array(
   &#39;name&#39; => 'jack',
   'age' => 18,
   'city' => 'beijing'
);

echo json_encode($person);
?>

Output result:

{"name":"jack","age":18,"city":"beijing"}

As you can see, the function of json_encode() function is to convert the array or object into String in json format. In the example, we define an object $person, and then use the json_encode() function to convert the $person object into a string in json format and output it.

2. Using the json_encode() function with parameters

In addition to converting an object array into a string in json format, the json_encode() function can also accept 4 parameters.

$a. $value parameter

The $value parameter is used to pass the object (or array) that needs to be converted. The $value parameter can be any PHP type except a resource type. In specific use, we will find that a nested or most nested array or object can contain multiple key-value pairs, nests, arrays or objects. When encountering this situation, you can use this syntax to construct a new array or object.

Sample code:

<?php //嵌套数组和对象的例子
$person = array(
   &#39;name&#39; => 'jack',
   'age' => 18,
   'city' => 'beijing',
   'hobby' => array(
       'reading',
       'music',
       'sports',
       'travel'
   ),
   'friends' => array(
       array(
           'name' => 'tom',
           'phone' => '13812999010'
       ),
       array(
           'name' => 'lily',
           'phone' => '13812999020'
       )
   )
);
//使用json_encode()的方式将$person数组转换为json格式字符串
echo json_encode($person);
?>

Output result:

{"name":"jack","age":18,"city":"beijing","hobby":["reading","music","sports","travel"],"friends":[{"name":"tom","phone":"13812999010"},{"name":"lily","phone":"13812999020"}]}

As you can see, the json_encode() function supports nested arrays and objects, which is useful for some more complex data formats. The language is very convenient and practical.

$b. $options parameter

The $options parameter is used to specify how to convert objects and arrays. For example, if you want to disable UTF-8 encoding in the output json string, you can use the JSON_UNESCAPED_UNICODE option. This option causes all non-English characters in the output to appear in their original representation.

Sample code:

<?php $person = array(
   &#39;name&#39; => 'jack',
   'age' => 18,
   'city' => 'beijing'
);

echo json_encode($person, JSON_UNESCAPED_UNICODE);
?>

Output result:

{"name":"jack","age":18,"city":"beijing"}

$c. $depth parameter

The $depth parameter is used to specify the object or array to be converted into The maximum depth before the json string. This parameter is valid if it is greater than 0, otherwise it is invalid. If the data depth exceeds the specified depth, the json_encode() function will return FALSE. By default, the $depth parameter is 512.

Sample code:

<?php $person = array(
   &#39;name&#39; => 'jack',
   'age' => 18,
   'city' => 'beijing',
   'hobby' => array(
       'reading',
       'music',
       'sports',
       'travel'
   ),
   'friends' => array(
       array(
           'name' => 'tom',
           'phone' => '13812999010'
       ),
       array(
           'name' => 'lily',
           'phone' => '13812999020'
       )
   )
);

echo json_encode($person, JSON_PRETTY_PRINT, 3);
?>

Output result:

{
   "name": "jack",
   "age": 18,
   "city": "beijing",
   "hobby": [
       "reading",
       "music",
       "sports",
       "travel"
   ],
   "friends": [
       {
           "name": "tom",
           "phone": "13812999010"
       },
       {
           "name": "lily",
           "phone": "13812999020"
       }
   ]
}

We can see that by using JSON_PRETTY_PRINT and $depth parameters, the output json string will be formatted and the entire object will be indented.

$d. $reserved parameter

The $reserved parameter specifies the action to be taken when the member name in the object or array conflicts with PHP reserved words. The default action is to add an underscore. This parameter only takes effect when JSON_FORCE_OBJECT is used as an option.

3. Exception handling

When using the json_encode() function for JSON encoding, some exceptions may occur, which require special handling, otherwise the json_encode() function will not work properly. .

$a. Encoding issues

If you want to embed an ISO-8859-1 encoded non-unicode string in the name key of $person, json_encode() will fail. However, if the relevant string is converted to Unicode, it encodes fine.

Sample code:

<?php $data = array(
   "name" => "Manfred",
   "age" => "31",
   "city" => "车里雅宾斯克",
   "UTF8" => "こんにちは"
);

foreach ($data as $key => $value) {
   if (!mb_detect_encoding($value, 'utf-8', true)) {
       $data[$key] = mb_convert_encoding($value, 'UTF-8', 'ISO-8859-1');
   }
}

echo json_encode($data);
?>

Output result:

{"name":"Manfred","age":"31","city":"\u8f66\u91cc\u96c6\u5bbe\u65af\u514b","UTF8":"こんにちは"}

As you can see, after converting the ISO-8859-1 string to a UTF-8 string, json_encode( ) function successfully converted the object into JSON format.

$b. UTF-8 BOM header issue

If you include a string encoded in the UTF-8 BOM header in the object array, the json_encode() function will not work. Therefore, when writing a program that contains BOM header encoding, you should manually remove the BOM header so that problems will not occur when using the json_encode() function.

c. Multi-byte array issues

The json_encode() function only accepts correct UTF-8 strings and does not accept other multi-byte encoding schemes. If the object array contains these encoding schemes, you need to use the mb_convert_encoding() function to convert them to UTF-8 strings.

Sample code:

<?php $array = [&#39;你好&#39;, &#39;こんにちは&#39;, &#39;Привет&#39;];
$json = json_encode($array);
echo $json;

// Error: Malformed UTF-8 characters, possibly incorrectly encoded

Output result:

Error: Malformed UTF-8 characters, possibly incorrectly encoded

Here we can see that an exception is caused due to converting a multi-byte array to a json string. We can pass Use mb_convert_encoding() to solve this problem.

Sample code:

<?php $array = [&#39;你好&#39;, &#39;こんにちは&#39;, &#39;Привет&#39;];
$json = json_encode(array_map(function ($str) {
   return mb_convert_encoding($str, &#39;UTF-8&#39;, &#39;UTF-8&#39;);
}, $array));
echo $json;
?>

Output result:

["你好","こんにちは","Привет"]

In short, json_encode() is a very convenient function that can help us convert an object array into json format characters string. In use, you need to clearly understand the solutions to common problems in order to better use this function.

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