Json decode example in php

Decode JSON in PHP: A Comprehensive Guide with Examples

Learn how to decode JSON in PHP with the built-in functions json_decode(), and handle common issues with invalid JSON strings. This guide provides examples and best practices for working with JSON data.

• Understanding JSON in PHP
• Decoding JSON in PHP
• Encoding JSON in PHP
• Best Practices for Working with JSON Data
• Improvements in PHP 7
• Other helpful PHP code examples for decoding JSON strings
• Conclusion
• How to decode a JSON string in PHP?
• How to print JSON decode data in PHP?
• How to create a JSON string in PHP?
• How to get JSON data in array in PHP?

JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write and easy for machines to parse and generate. It has become an essential component of web development due to its simplicity, flexibility, and wide support. In this blog post, you will learn how to decode json in php using the built-in functions and best practices.

Understanding JSON in PHP

JSON is a text format that consists of a collection of key-value pairs or ordered lists of values. It is often used to transmit data between a server and a web application, as it is language-independent and can be easily parsed by JavaScript. JSON has several advantages over XML, including a simpler syntax, faster parsing, and better data representation.

PHP provides two built-in functions for working with JSON data: json_encode() and json_decode() . These functions allow you to convert PHP objects or arrays to JSON strings and vice versa.

To use JSON data in PHP, you first need to decode it. The json_decode() function is used for this purpose.

Decoding JSON in PHP

The json_decode() function is used to decode a JSON string into a PHP object or associative array. It takes two parameters: the JSON string to be decoded and a boolean flag that determines whether to return an object or an array. By default, it returns an object.

Here’s an example of how to decode a JSON string in PHP:

$json_string = ''; $data = json_decode($json_string); echo $data->name; // Output: John 

In this example, we decode a JSON string that contains three key-value pairs (name, age, and city) into a PHP object. We then access the “name” property of the object and print it to the screen.

It is essential to ensure that the JSON string is valid and properly encoded in UTF-8 format. Otherwise, the json_decode() function may fail and return null. You can use the json_last_error() function to check whether an error occurred during decoding and the json_last_error_msg() function to get a human-readable error message.

Encoding JSON in PHP

The json_encode() function is used to encode a PHP object or array into a JSON string. It takes one parameter, the data to be encoded, and returns a JSON string.

Here’s an example of how to encode a PHP array into a JSON string:

$data = array("name" => "John", "age" => 30, "city" => "New York"); $json_string = json_encode($data); echo $json_string; // Output: 

In this example, we create a PHP array that contains three key-value pairs and encode it into a JSON string using the json_encode() function.

The json_encode() function provides several options for formatting and encoding JSON data. For example, you can use the JSON_PRETTY_PRINT flag to format the JSON string with indentation and line breaks, or the JSON_UNESCAPED_UNICODE flag to encode Unicode characters as-is, without escaping them.

Best Practices for Working with JSON Data

When working with JSON data in PHP, it is essential to follow some best practices to ensure that your code is secure, efficient, and maintainable.

First, it is crucial to use consistent naming conventions and avoid redundant data. This will improve the readability and maintainability of your code and reduce the size of JSON strings.

Second, you should minimize the size of JSON strings by removing unnecessary whitespace and using short property names. This will reduce the bandwidth and storage requirements of your application and improve its performance.

Third, you should validate JSON data before decoding it to prevent security vulnerabilities and errors. You can use the json_last_error() function to check whether an error occurred during decoding and the json_last_error_msg() function to get a human-readable error message.

Finally, you should handle common issues, such as encoding and decoding errors, null values, and circular references. You can use the json_encode() and json_decode() functions with appropriate flags and options to handle these issues.

Improvements in PHP 7

PHP 7 introduced several improvements to the json_decode() function, including better performance and memory usage, and better error reporting.

For example, the json_decode() function in PHP 7 can handle large JSON strings more efficiently and return null instead of throwing an error if the input is invalid. It also introduced the JSON_THROW_ON_ERROR flag, which causes the json_decode() function to throw an exception instead of returning null on error.

You can use the json_last_error_msg() function with the JSON_THROW_ON_ERROR flag to get a detailed error message that includes the line and column numbers of the error.

Other helpful PHP code examples for decoding JSON strings

In php, php json_decode code example

$personJSON = '';$person = json_decode($personJSON);echo $person->name; // Johny Carson

In php, json stringify php decode code example

$postedData = $_POST["JSONfullInfoArray"]; $tempData = str_replace("\\", "",$postedData); $cleanData = json_decode($tempData); var_dump($cleanData);

In php, php decode json file code example

$json = json_decode(file_get_contents('/path/to/your/file.json'));

In php, php parse json code example

// scrap this: $data = json_decode($rawdata);// use this: $data = json_decode($rawdata, true); echo $data["key1"];

';$personInfo = json_decode(json);echo $personInfo->age;?>

In php, php try json decode code example

/** Checks if JSON and returns decoded as an array, if not, returns false, but you can pass the second parameter true, if you need to return a string in case it's not JSON */ function tryJsonDecode($string, $returnString = false) < $arr = json_decode($string); if (json_last_error() === JSON_ERROR_NONE) < return $arr; >else < return ($returnString) ? $string : false; >>

Conclusion

JSON is a powerful and flexible data interchange format that is widely used in web development. In this blog post, you learned how to decode JSON in PHP using the json_decode() function, how to encode PHP objects and arrays into JSON strings using the json_encode() function, and best practices for working with json data in PHP. You also learned about the improvements in PHP 7 and how to handle common issues.

By following these guidelines, you can create robust and efficient web applications that leverage the power of JSON and PHP. For more information, check out the official PHP documentation and other resources online.

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json_decode

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

Parameters

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.

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 .

Maximum nesting depth of the structure being decoded. The value must be greater than 0 , and less than or equal to 2147483647 .

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 nesting limit.

Errors/Exceptions

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.

Changelog

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_ .

Examples

Example #1 json_decode() examples

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.

$obj = json_decode ( $json );
print $obj ->< 'foo-bar' >; // 12345

Example #3 common mistakes using json_decode()

// 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

// 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

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

User Contributed Notes 8 notes

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 = »;
$array = json_decode($json, true); // decode as associative hash
print json_encode($array) . PHP_EOL;

This will output a different JSON string than the original:

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 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:

If you want to enforce an array to encode to a JSON object, use:

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