json_decode
(PHP 5 >= 5.2.0, PHP 7, PECL json >= 1.2.0)
json_decode — Decodes a JSON string
Description
$json
[, bool $assoc = FALSE
[, int $depth = 512
[, int $options = 0
]]] ) : mixedTakes a JSON encoded string and converts it into a PHP variable.
Parameters
-
json -
The
jsonstring 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_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.
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.
Changelog
| Version | Description |
|---|---|
| 7.3.0 |
JSON_THROW_ON_ERROR
options was added.
|
| 7.2.0 |
JSON_INVALID_UTF8_IGNORE, and
JSON_INVALID_UTF8_SUBSTITUTE
options 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_. |
| 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 |
JSON_BIGINT_AS_STRING, and
JSON_OBJECT_AS_ARRAY
options were added.
|
| 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. |
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.
See Also
- json_encode() - Returns the JSON representation of a value
- json_last_error() - Returns the last error occurred
English translation
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Document created the 30/01/2003, last modified the 26/10/2018
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References
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