Php creating json object

PHP Json_encode: Serialize PHP Objects to JSON

PHP is a server-side scripting language for creating your website’s backend system that can serve webpages, communicate with databases, and exchange data over the internet. A decent backend framework like PHP needs to be capable of providing and processing data in any format (e.g., XML, JSON, etc.) to be socially accepted in a society of skilled web development frameworks.

Since JSON is a ubiquitous data format for sharing and storing data, it is vital that a PHP backend allows processing of JSON data. This is where json_encode (and json_decode) come into the picture and enable PHP processed data to be compatible with frameworks and systems that deal with JSON data and make way for easier and faster web development.

In this post, we’ll learn about the JSON format, about the json_encode() function — what it is, why it is required, and how it can be used to convert PHP data structures into JSON format, all with examples. In the end, we’ll also see how we can decode JSON data to be able to process it. Let’s get started!

Use these links to navigate the guide:

What is the JSON_Encode Function?

What is JSON?

JSON (JavaScript Object Notation) is one of the most popular open-standard file formats used for storing and sharing data. It uses human-readable text to represent data using attribute-value pairs and array data types.

This is what a common JSON object looks like —

We’ll be using this example in the sections below to understand how we can encode PHP data into JSON format.

JSON allows us to represent and encapsulate complex data in an organized fashion that can be shared easily across the internet. Even though JSON derives its name from JavaScript, JSON was created to be used by all programming languages.

Let’s see how we can convert our PHP variables into JSON format.

JSON_Encode — PHP variables to JSON

json_encode() is a native PHP function that allows you to convert PHP data into the JSON format.

json_encode ( mixed $value [, int $options = 0 [, int $depth = 512 ]] ) : string 

The function takes in a PHP object ($value) and returns a JSON string (or False if the operation fails). Don’t worry about the $options and $depth parameters; you’re seldom going to need them.

Let’s look at a simple example —

 1, 'b' => 2); echo json_encode($arr); ?>

Why encode to JSON?

As we saw above, JSON is one of the most common formats for exchanging data over the internet. Therefore, it can be imperative in some cases for PHP servers to provide JSON-encoded data and to be able to process it.

Let’s see how we can encode various PHP data structures into JSON using json_encode() .

Convert PHP Strings to JSON

JSON encoding for a string is the string itself. Therefore, encoding a PHP string into JSON is quite simple; it results in the same string being returned.

Let’s see this using an example —

PHP String to JSON Example

Convert PHP Objects to JSON

Since the information in JSON is stored in key/value pairs, json_encode() is more likely to be used to encode PHP objects and their instance variables.

PHP Object to JSON Example

Let’s understand how we can JSON-encode a PHP object by creating an instance of a Book class based on the Library example we saw above (Sec 1.1). We’ll create two instance variables for the book’s instance and encode the object using json_encode().

 $book = new Book(); $book->id = 101; $book->label = "Lorem ipsum"; $jsonData = json_encode($book); echo $jsonData."\n"; ?>

Convert PHP Array to JSON

There are three types of arrays in PHP, namely — Indexed arrays, Associative arrays, and Multidimensional arrays. Let us look at what these are and some examples of how we can encode each of these into JSON —

Indexed Array to JSON

Indexed arrays are conventional arrays that are represented by index numbers.

Example: $arr = array(1,2,3,4); // [1,2,3,4]

Converting them to JSON is quite easy —

Associative Array to JSON

Associative arrays are arrays that use named keys as indices for your values.

Example: $age = array(«John»=>»11», «Ken»=>»19», «Tim»=>»14»);

We can also arrive at the book JSON object that we saw above by encoding an Associative array as such —

101, "label"=>"Lorem Ipsum"); echo json_encode($book); ?>

Notice how an Indexed array is represented by an array in JSON, whereas Associative arrays take the form of a complete JSON object after being encoded.

Multidimensional Array to JSON

Multidimensional arrays can be created by nesting arrays into each other as such-

$multid_arr = array( array(1,2,3,4), array(1,2,3,4), ); 

We can create a Multidimensional array to store a list of books for our library example. Let’s create one and encode that into JSON.

101, "label"=>"Lorem Ipsum"), array("id"=>102, "label"=>"Dolor sir amet"), array("id"=>103, "label"=>"Lorem Ipsum dolor"), ); echo json_encode($books); ?>

Putting it all together

Now that we have seen how json_encode( ) is used in different contexts, for encoding different PHP data types, let’s put all of our learnings together to create JSON data for the Library example we saw above.

 class Library < >class Book < >$book1 = new Book(); $book1->id = 101; $book1->label = "Lorem ipsum"; $book2 = new Book(); $book2->id = 102; $book2->label = "Dolor sir amet"; $books = array($book1, $book2); $library = new Library(); $library->books = $books; $myClass = new MyClass(); $myClass->library = $library; $jsonData = json_encode($myClass); echo $jsonData."\n"; 

Well, that was fun! Now before we wrap up, I think it’s worthwhile to see how we can convert JSON data back to PHP variables.

JSON_Decode — JSON to PHP variables

In the very likely case of your JavaScript front-end sending JSON-based data back to your PHP server, you would need a way to decode the JSON data in a way that can be processed by PHP.

We can use PHP’s json_decode() function for the same, which takes in a JSON encoded string and returns the corresponding PHP variable.

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

$assoc parameter (False by default) is used to specify whether you need the function to return an Associative array or a standard class Object.

JSON_Decode example

Let’s try to retrieve the book object that we encoded into JSON above by decoding it using php_decode() .

'; $book = json_decode($book_json); var_dump($book); ?>

Note how by default a stdClass object is returned. For decoding it as an Associative array, set the $assoc parameter to True as such —

$book = json_decode($book_json, True);

This will result in an Associative array being returned.

Try the JSON_Encode Function for Yourself

In this post, we read about the JSON (JavaScript Object Notation) format, why it is essential, and how we can convert different PHP variables into JSON using json_encode() . We also saw how we could use json_decode() to decode JSON data into PHP variables. With this understanding of processing JSON data using PHP, go ahead and encode your PHP objects into JSON and share them across the internet. All of this while staying at home. Stay healthy, stay safe!

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PHP JSON

Summary: in this tutorial, you will learn how to convert data in PHP to JSON data and vice versa using the PHP JSON extension.

JSON stands for JavaScript Object Notation. JSON is designed as a lightweight data-interchange format.

JSON is built on two structures:

• A collection of name/value pairs called JSON objects. JSON objects are equivalent to associative arrays in PHP.
• An ordered list of values called arrays. They’re equivalent to indexed arrays in PHP.

The JSON format is human-readable and easy for computers to parse. Even though JSON syntax derives from JavaScript, it’s designed to be language-independent.

PHP JSON extension

PHP natively supports JSON via the JSON extension. The JSON extension provides you with some handy functions that convert data from PHP to JSON format and vice versa.

Since the JSON extension comes with PHP installation by default, you don’t need to do any extra configuration to make it works.

Converting PHP variables to JSON using json_encode() function

To get a JSON representation of a variable, you use the json_encode() function:

json_encode ( mixed $value , int $flags = 0 , int $depth = 512 ) : string|falseCode language: PHP (php)

The following example uses the json_encode() function to convert an indexed array in PHP to JSON format:

 $names = ['Alice', 'Bob', 'John']; $json_data = json_encode($names); // return JSON to the browsers header('Content-type:application/json'); echo $json_data;Code language: PHP (php)

• First, define an array of strings that consists of three elements.
• Second, convert the array to JSON using the json_encode() function.
• Third, return the JSON data to the browsers by setting the content type of the document to appplication/json using the header() function.

[ "Alice", "Bob", "John" ]Code language: JSON / JSON with Comments (json)

The following example uses the json_encode() function to convert an associative array in PHP to an object in JSON:

 $person = [ 'name' => 'Alice', 'age' => 20 ]; header('Content-type:application/json'); echo json_encode($person);Code language: PHP (php)

< name: "Alice", age: 20 >Code language: PHP (php)

In practice, you would select data from a database and use the json_encode() function to convert it to the JSON data.

Converting JSON data to PHP variables

To convert JSON data to a variable in PHP, you use the json_decode() function:

json_decode ( string $json , bool|null $associative = null , int $depth = 512 , int $flags = 0 ) : mixedCode language: PHP (php)

The following example shows how to use json_decode() function to convert JSON data to a variable in PHP:

 $json_data = ''; $person = json_decode($json_data); var_dump($person);Code language: PHP (php)

object(stdClass)#1 (2) ["name"] => string(5) "Alice" ["age"] => int(20) > Code language: PHP (php)

In this example, the json_decode() function converts an object in JSON to an object in PHP. The object is an instance of the stdClass class. To convert JSON data to an object of a specific class, you need to manually map the JSON key/value pairs to object properties. Or you can use a third-party package.

Serializing PHP objects

To serialize an object to JSON data, you need to implement the JsonSerializable interface. The JsonSerializable interface has the jsonSerialize() method that specifies the JSON representation of the object.

For example, the following shows how to implement the JsonSerializable interface and use the json_encode() function to serialize the object:

 class Person implements JsonSerializable < private $name; private $age; public function __construct(string $name, int $age) < $this->name = $name; $this->age = $age; > public function jsonSerialize() < return [ 'name' => $this->name, 'age' => $this->age ]; > > // serialize object to json $alice = new Person('Alice', 20); echo json_encode($alice);Code language: PHP (php)

"name":"Alice","age":20>Code language: PHP (php)

• First, define a Person class that implements the JsonSerializable interface.
• Second, return an array that consists of name and age properties from the jsonSerialize() method. The json_encode() function will use the return value of this method to create JSON data.
• Third, create a new Person object and serialize it to JSON data using the json_encode() function.

Summary

• JSON is a lightweight data-interchange format.
• Use the json_encode() function to convert PHP variables to JSON.
• Use the json_decode() function to convert JSON data to PHP variables.
• Implement the JsonSerializable interface to specify the JSON representation of an object.

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