How to send JSON POST request with PHP

A guide on how to use PHP to send a POST request with JSON data using cURL. The article includes a runnable PHP example along with detailed explanations.

In this article, we will learn how to send a POST request with JSON data from PHP to an API using cURL. This is useful when you need to send JSON data from your PHP application to web services.

PHP Code:

<?php
// The URL of the API or server to send the request to
$url = "https://api.example.com/data";

// Data to send as JSON
$data = array(
    "name" => "John",
    "email" => "[email protected]",
    "age" => 30
);

// Convert PHP array to JSON
$jsonData = json_encode($data);

// Initialize cURL
$ch = curl_init($url);

// Set cURL options
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Content-Type: application/json',
    'Content-Length: ' . strlen($jsonData)
));
curl_setopt($ch, CURLOPT_POSTFIELDS, $jsonData);

// Execute request and get the response
$response = curl_exec($ch);

// Check for errors
if ($response === false) {
    $error = curl_error($ch);
    echo "cURL Error: $error";
} else {
    echo "Response: $response";
}

// Close cURL session
curl_close($ch);
?>

Detailed explanation:

1. $url: The URL of the API you want to send the POST request to.
2. $data: An array containing the data to be sent as JSON.
3. json_encode(): Converts the PHP array into JSON format.
4. curl_init(): Initializes a cURL session with the target URL.
5. curl_setopt(): Sets the options for the cURL session, such as sending a POST request, setting the Content-Type to application/json.
6. curl_exec(): Executes the cURL request and returns the server's response.
7. curl_error(): Checks and prints an error message if the cURL request fails.
8. curl_close(): Closes the cURL session after it is complete.

System requirements:

• PHP Version: PHP 5.6 or later.
• cURL Library: Ensure that cURL is installed and enabled on your server.

How to install the libraries:

• If cURL is not installed, you can install it on your server (Linux):

  sudo apt-get install php-curl
  

Tips:

• Always check the API's response to handle any potential errors.
• Make sure the JSON data is correctly encoded before sending.

---