(PHP 5 >= 5.2.0, PHP 7, PHP 8, PECL json >= 1.2.0)
json_decode — Decodes a JSON string
Takes a JSON encoded string and converts it into a PHP value.
json
The json string being decoded.
This function only works with UTF-8 encoded strings.
Note:
PHP implements a superset of JSON as specified in the original » RFC 7159.
associative
When true , JSON objects will be returned as
associative array s; when false , JSON objects will be returned as object s.
When null , JSON objects will be returned as associative array s or
object s depending on whether JSON_OBJECT_AS_ARRAY
is set in the flags.
depth
Maximum nesting depth of the structure being decoded.
The value must be greater than 0,
and less than or equal to 2147483647.
flags
Bitmask of
JSON_BIGINT_AS_STRING ,
JSON_INVALID_UTF8_IGNORE ,
JSON_INVALID_UTF8_SUBSTITUTE ,
JSON_OBJECT_AS_ARRAY ,
JSON_THROW_ON_ERROR .
The behaviour of these constants is described on the
JSON constants page.
Returns the value encoded in json as an appropriate
PHP type. Unquoted values true, false
and null are returned as true ,
false and null respectively. null is returned if the
json cannot be decoded or if the encoded data is
deeper than the nesting limit.
If depth is outside the allowed range,
a ValueError is thrown as of PHP 8.0.0,
while previously, an error of level E_WARNING was raised.
| Version | Description |
|---|---|
| 7.3.0 |
JSON_THROW_ON_ERROR
flags was added.
|
| 7.2.0 |
associative is nullable now.
|
| 7.2.0 |
JSON_INVALID_UTF8_IGNORE , and
JSON_INVALID_UTF8_SUBSTITUTE
flags were added.
|
| 7.1.0 |
An empty JSON key ("") can be encoded to the empty object property
instead of using a key with value _empty_.
|
Example #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));
?>The above example will output:
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)
}
Example #2 Accessing invalid object properties
Accessing elements within an object that contain characters not permitted under PHP's naming convention (e.g. the hyphen) can be accomplished by encapsulating the element name within braces and the apostrophe.
<?php
$json = '{"foo-bar": 12345}';
$obj = json_decode($json);
print $obj->{'foo-bar'}; // 12345
?>Example #3 common mistakes using json_decode()
<?php
// the following strings are valid JavaScript but not valid JSON
// the name and value must be enclosed in double quotes
// single quotes are not valid
$bad_json = "{ 'bar': 'baz' }";
json_decode($bad_json); // null
// the name must be enclosed in double quotes
$bad_json = '{ bar: "baz" }';
json_decode($bad_json); // null
// trailing commas are not allowed
$bad_json = '{ bar: "baz", }';
json_decode($bad_json); // null
?>Example #4 depth errors
<?php
// Encode some data with a maximum depth of 4 (array -> array -> array -> string)
$json = json_encode(
array(
1 => array(
'English' => array(
'One',
'January'
),
'French' => array(
'Une',
'Janvier'
)
)
)
);
// Show the errors for different depths.
var_dump(json_decode($json, true, 4));
echo 'Last error: ', json_last_error_msg(), PHP_EOL, PHP_EOL;
var_dump(json_decode($json, true, 3));
echo 'Last error: ', json_last_error_msg(), PHP_EOL, PHP_EOL;
?>The above example will output:
array(1) {
[1]=>
array(2) {
["English"]=>
array(2) {
[0]=>
string(3) "One"
[1]=>
string(7) "January"
}
["French"]=>
array(2) {
[0]=>
string(3) "Une"
[1]=>
string(7) "Janvier"
}
}
}
Last error: No error
NULL
Last error: Maximum stack depth exceeded
Example #5 json_decode() of large integers
<?php
$json = '{"number": 12345678901234567890}';
var_dump(json_decode($json));
var_dump(json_decode($json, false, 512, JSON_BIGINT_AS_STRING));
?>The above example will output:
object(stdClass)#1 (1) {
["number"]=>
float(1.2345678901235E+19)
}
object(stdClass)#1 (1) {
["number"]=>
string(20) "12345678901234567890"
}
Note:
The JSON spec is not JavaScript, but a subset of JavaScript.
Note:
In the event of a failure to decode, json_last_error() can be used to determine the exact nature of the error.
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 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.When JSON_OBJECT_AS_ARRAY is true, "json_decode($json)" is the same as "json_decode($json, false)" and return object actually.
<?php
$php_constants = (get_defined_constants(true));
printf($php_constants['json']['JSON_OBJECT_AS_ARRAY'] . PHP_EOL);
$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
$data = json_decode($json);
printf(is_array($data) . PHP_EOL);//false
var_dump($data);
$data = json_decode($json, false);
printf(is_array($data) . PHP_EOL);//false
var_dump($data);
$data = json_decode($json, true);
printf(is_array($data) . PHP_EOL);//true
var_dump($data);
?>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 $infull->fullname();Browsers don't choke on integers _starting_ with BigInt (64 bits), but before that (53 bits). The introduction of BigInt to modern browsers doesn't help much, when JSON handling functions do not support it. So I am trying to remedy that. My approach is to handle the decoded array before re-encoding it to a string:
<?php
function fix_large_int(&$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"]}
?>The return value says "Returns the value encoded in json as an appropriate PHP type.", that seems to be the description for the json_encode.