How to Convert a String to JSON Object in PHP ?

Last Updated : 18 Jul, 2024

Given a String, the task is to convert the given string into a JSON object in PHP. JSON (JavaScript Object Notation) is a widely used data interchange format. PHP provides convenient functions to work with JSON data.

Table of Content

Using json_decode() to Convert to an Array
Handling Errors with json_last_error() and json_last_error_msg() Methods
Using stdClass object and json_encode()
Using Associative Arrays and json_encode()

Approach 1: Using json_decode() to Convert to an Array

The json_decode() function is a versatile and commonly used method to convert a JSON-formatted string into a PHP object.

PHP

<?php 

// Your JSON-formatted string 
$jsonString = '{"key1": "value1", "key2": "value2", "key3": "value3"}'; 

// Convert JSON string to a PHP object 
$phpObject = json_decode($jsonString); 

// Output the result 
print_r($phpObject); 
?>

Output

stdClass Object
(
    [key1] => value1
    [key2] => value2
    [key3] => value3
)

Approach 2: Handling Errors with json_last_error() and json_last_error_msg() Methods

It's essential to handle errors that may occur during the decoding process. The json_last_error() function returns the last error occurred, and json_last_error_msg() provides a human-readable error message.

PHP

<?php 

$jsonString = '{"key1": "value1", "key2": "value2", "key3": "value3"}'; 

// Decode the JSON string 
$decodedData = json_decode($jsonString); 

// Check for errors 
if ($decodedData === null) { 
    echo "Error decoding JSON: "
        . json_last_error_msg(); 
} else { 
    
    // Successfully decoded 
    print_r($decodedData); 
} 

?>

Output

stdClass Object
(
    [key1] => value1
    [key2] => value2
    [key3] => value3
)

Approach 3: Using stdClass object and json_encode()

Using stdClass object, create properties (message) and assign values (Hello, World!). Encode object using json_encode() to JSON format. Useful for custom data structures requiring flexibility in JSON conversion

Example

PHP

<?php
$obj = new stdClass();
$obj->message = "Hello, World!";
$jsonObject = json_encode($obj);
echo $jsonObject;
?>

Output

{"message":"Hello, World!"}

Approach 4: Using Associative Arrays and json_encode()

Another method to convert a string into a JSON object is by first converting the string into an associative array and then using the json_encode() function. This approach is particularly useful when you have a delimited string that needs to be structured into key-value pairs.

Example: This approach is particularly useful when dealing with custom delimited strings and needing to convert them into JSON objects in PHP.

PHP

<?php
function stringToJson($inputString) {
    // Example input string: "name:John,age:30,city:New York"
    
    // Split the string by commas to get key-value pairs
    $pairs = explode(',', $inputString);
    
    // Initialize an empty associative array
    $assocArray = [];
    
    // Loop through each pair and split by colon to get key and value
    foreach ($pairs as $pair) {
        list($key, $value) = explode(':', $pair);
        $assocArray[trim($key)] = trim($value);
    }
    
    // Convert the associative array to a JSON object
    $jsonObject = json_encode($assocArray);
    
    return $jsonObject;
}

// Sample usage
$inputString = "name:John,age:30,city:New York";
$jsonObject = stringToJson($inputString);
echo $jsonObject; 

?>

Output

{"name":"John","age":"30","city":"New York"}

Approach 5: Using explode() and json_encode()

This approach involves using the explode() function to split a string into an array based on a delimiter and then converting that array into an associative array before using json_encode() to create the JSON object. This method is useful when you have a string in a specific format and want to structure it into a JSON object.

Example: