JSON Functions
PHP Manual

json_decode

Decodes a JSON string

Description

mixed json_decode ( string $json [, bool $assoc = false [, int $depth = 512 [, int $options = 0 ]]] )

Takes a JSON encoded string and converts it into a PHP variable.

Parameters

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.

assoc

When TRUE, returned objects will be converted into associative arrays.

depth

User specified recursion depth.

options

Bitmask of JSON decode options. Currently there are two supported options. The first is JSON_BIGINT_AS_STRING that allows casting big integers to string instead of floats which is the default. The second option is JSON_OBJECT_AS_ARRAY that has the same effect as setting assoc to TRUE.

Return Values

Returns the value encoded in json in appropriate PHP type. 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 recursion limit.

Examples

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 the data.
$json = json_encode(
    array(
        1 => array(
            'English' => array(
                'One',
                'January'
            ),
            'French' => array(
                'Une',
                'Janvier'
            )
        )
    )
);

// Define the errors.
$constants = get_defined_constants(true);
$json_errors = array();
foreach ($constants["json"] as $name => $value) {
    if (!strncmp($name, "JSON_ERROR_", 11)) {
        $json_errors[$value] = $name;
    }
}

// Show the errors for different depths.
foreach (range(4, 3, -1) as $depth) {
    var_dump(json_decode($json, true, $depth));
    echo 'Last error: ', $json_errors[json_last_error()], 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: JSON_ERROR_NONE

NULL
Last error: JSON_ERROR_DEPTH

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"
}

Notes

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.

Changelog

Version Description
7.1.0 An empty JSON key ("") can be encoded to the empty object property instead of using a key with value _empty_.
7.0.0 Rejected RFC 7159 incompatible number formats - top level (07, 0xff, .1, -.1) and all levels ([1.], [1.e1])
7.0.0 An empty PHP string or value that after casting to string is an empty string (NULL, FALSE) results in JSON syntax error.
5.6.0 Invalid non-lowercased variants of the true, false and null literals are no longer accepted as valid input, and will generate warnings.
5.4.0 The options parameter was added.
5.3.0 Added the optional depth. The default recursion depth was increased from 128 to 512
5.2.3 The nesting limit was increased from 20 to 128
5.2.1 Added support for JSON decoding of basic types.

See Also

  • json_encode
  • json_last_error