json_decode
(PHP 5 >= 5.2.0, PECL json:1.2.0-1.2.1)
json_decode — Decodes a JSON string
Описание
Takes a JSON encoded string and converts it into a PHP variable.
Список параметров
Возвращаемые значения
Returns an object or if the optional assoc parameter is TRUE, an associative array is instead returned.
Примеры
Пример #1 json_decode() examples
<?php
$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
var_dump(json_decode($json));
var_dump(json_decode($json, true));
?>
Результат выполнения данного примера:
object(stdClass)#1 (5) { ["a"] => int(1) ["b"] => int(2) ["c"] => int(3) ["d"] => int(4) ["e"] => int(5) } array(5) { ["a"] => int(1) ["b"] => int(2) ["c"] => int(3) ["d"] => int(4) ["e"] => int(5) }
<?php
$json = '{"foo-bar": 12345}';
$obj = json_decode($json);
print $obj->{'foo-bar'}; // 12345
?>
Примечания
Предостережение
This function will return false if the JSON encoded data is deeper than 127 elements.
Список изменений
Версия | Описание |
---|---|
5.2.3 | The nesting limit was increased from 20 to 128 |
Коментарии
Warning: As the section "return values" mentions, the return value NULL is ambiguos. To repeat, it can mean three things:
* The input string had the value "null"
* There was an error while parsing the input data
* The encoded data was deeper than the recursion limit
To distinguish these cases, json_last_error() can be used.
if you're using ajax to post, and your JavaScript code looks like this:
<code>
var xhttp = new XMLHttpRequest();
xhttp.open("POST", "something.php", true);
xhttp.setRequestHeader("Content-Type", "application/json");
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
// do something
}
};
var data = {some: "thing"};
xhttp.send(JSON.stringify(data));
</code>
then in <code>something.php</code> you can retrieve your json by doing
<?php
$data = json_decode(file_get_contents("php://input"), true);
?>
Browsers don't choke on integers _starting_ with BigInt (64 bits), but before that (53 bits). The introduction of BigInt to modern browsers doesn't help much, when JSON handling functions do not support it. So I am trying to remedy that. My approach is to handle the decoded array before re-encoding it to a string:
<?php
function fix_large_int(&$value)
{
if (is_int($value) && $value > 9007199254740991)
$value = strval($value);
}
$json_str = '{"id":[1234567890123456789,12345678901234567890]}';
$json_arr = json_decode($json_str, flags: JSON_BIGINT_AS_STRING | JSON_OBJECT_AS_ARRAY);
echo(json_encode($json_arr)); // {"id":[1234567890123456789,"12345678901234567890"]} (BigInt is already converted to a string here)
array_walk_recursive($json_arr, 'fix_large_int');
echo(json_encode($json_arr)); // {"id":["1234567890123456789","12345678901234567890"]}
?>
To load an object with data in json format:
function loadJSON($Obj, $json)
{
$dcod = json_decode($json);
$prop = get_object_vars ( $dcod );
foreach($prop as $key => $lock)
{
if(property_exists ( $Obj , $key ))
{
if(is_object($dcod->$key))
{
loadJSON($Obj->$key, json_encode($dcod->$key));
}
else
{
$Obj->$key = $dcod->$key;
}
}
}
}
<?php
$array = [0 => "foo", 1 => "bar", 2 => ["baz"]];
$associative = false;
var_dump(
json_decode(
json_encode($array),
$associative
)
);
?>
The above will output
<?php
/*
array (size=3)
0 => string 'foo' (length=3)
1 => string 'bar' (length=3)
2 =>
array (size=1)
0 => string 'baz' (length=3)
*/
?>
Considering <?php $associative = false; ?> one might expect
<?php
/*
object(stdClass)
public '0' => string 'foo' (length=3)
public '1' => string 'bar' (length=3)
public '2' =>
object(stdClass)
public '0' => string 'baz' (length=3)
*/
?>
an stdClass object instead of an array, but this is incorrect.
json_decode will always return an array for a sequentially encoded array, regardless of the ?bool $associative 2nd argument
Which is inline with the above mentioned docs/spec
> Returns the value encoded in json in appropriate PHP type
Considering that the 1st arg was a sequentially encoded array as a json string
'["foo","bar",["baz"]]'
On some PHP7+ systems php_json functions can be undefined (i faced it on Oracle Linux Enterprice with php 7.4 installed from REMI repository). If you have the same problem, try to install separated php-json module:
# yum install php-json
Hope this helps.
JSON can be decoded to PHP arrays by using the $associative = true option. Be wary that associative arrays in PHP can be a "list" or "object" when converted to/from JSON, depending on the keys (of absence of them).
You would expect that recoding and re-encoding will always yield the same JSON string, but take this example:
$json = '{"0": "No", "1": "Yes"}';
$array = json_decode($json, true); // decode as associative hash
print json_encode($array) . PHP_EOL;
This will output a different JSON string than the original:
["No","Yes"]
The object has turned into an array!
Similarly, a array that doesn't have consecutive zero based numerical indexes, will be encoded to a JSON object instead of a list.
$array = [
'first',
'second',
'third',
];
print json_encode($array) . PHP_EOL;
// remove the second element
unset($array[1]);
print json_encode($array) . PHP_EOL;
The output will be:
["first","second","third"]
{"0":"first","2":"third"}
The array has turned into an object!
In other words, decoding/encoding to/from PHP arrays is not always symmetrical, or might not always return what you expect!
On the other hand, decoding/encoding from/to stdClass objects (the default) is always symmetrical.
Arrays may be somewhat easier to work with/transform than objects. But especially if you need to decode, and re-encode json, it might be prudent to decode to objects and not arrays.
If you want to enforce an array to encode to a JSON list (all array keys will be discarded), use:
json_encode(array_values($array));
If you want to enforce an array to encode to a JSON object, use:
json_encode((object)$array);
See also: https://www.php.net/manual/en/function.array-is-list.php
To load an object with data in json format:
(bugfixed my previous comment)
<?php
function loadJSON($Obj, $json)
{
$dcod = json_decode($json);
$prop = get_object_vars ( $dcod );
foreach($prop as $key => $lock)
{
if(property_exists ( $Obj , $key ))
{
if(is_object($dcod->$key))
{
loadJSON($Obj->$key, json_encode($dcod->$key));
}
else
{
$Obj->$key = $dcod->$key;
}
}
}
return $Obj;
}
?>
Tested with:
<?php
class Name
{
public $first;
public $last;
public function fullname()
{
return $this->first . " " . $this->last;
}
}
$json = '{"first":"John","last":"Smith"}';
$infull = loadJSON((new Name), $json);
echo $infull->fullname();