Catch and parse JSON Post data in PHP
A few days ago I’ve been working a project which, as many other projects out there today, communicates with some external APIs. At some point, in order to perform some tests, I had to write an API endpoint within my project itself to fake the actual external API. I need to mention that the external API was expecting application/json content type, so basically the curl setup looked like this:
timeout_limit ); curl_setopt( $ch, CURLOPT_ENCODING, '' ); curl_setopt( $ch, CURLOPT_MAXREDIRS, 10 ); curl_setopt( $ch, CURLOPT_CUSTOMREQUEST, 'POST' ); curl_setopt( $ch, CURLOPT_POSTFIELDS, json_encode( $data ) ); curl_setopt( $ch, CURLOPT_HTTPHEADER, array( 'Content-Type: application/json' ) ); // . The issue was that when I’ve been trying to catch the POST data and use it, I was getting null as a value for both $_POST or $_REQUEST , and I couldn’t understand why 🤔. Apparently (and maybe many of you already knew that), if the data is sent as multipart/form-data or application/x-www-form-urlencoded then yes, you can use PHP globals $_POST or $_REQUEST to catch and use that data. But, if the data is sent as application/json , then prior to PHP 5.6 you could’ve use $HTTP_RAW_POST_DATA to grab the raw POST data, or (and based on PHP docs this is the preferable way to do it) use the php://input — a read-only stream that allows you to read raw data from the request body. So, as a result I ended up grabbing the POST data like this:
Php get posted json
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Receiving JSON POST data via PHP.
In a previous tutorial, I showed how to send JSON data via POST in PHP. This led to somebody asking me how to receive JSON POST data with PHP.
To receive RAW post data in PHP, you can use the php://input stream like so:
//Receive the RAW post data via the php://input IO stream. $content = file_get_contents("php://input"); Now, let’s take a look at an example where we attempt to receive and validate JSON POST data:
//Make sure that the content type of the POST request has been set to application/json $contentType = isset($_SERVER["CONTENT_TYPE"]) ? trim($_SERVER["CONTENT_TYPE"]) : ''; if(strcasecmp($contentType, 'application/json') != 0) < throw new Exception('Content type must be: application/json'); >//Receive the RAW post data. $content = trim(file_get_contents("php://input")); //Attempt to decode the incoming RAW post data from JSON. $decoded = json_decode($content, true); //If json_decode failed, the JSON is invalid. if(!is_array($decoded)) < throw new Exception('Received content contained invalid JSON!'); >//Process the JSON. A drill-down of the code sample above:
- We validate the request type by checking to see if it is POST. This will prevent the script from trying to process other request types such as GET.
- We validate the content type. In this case, we want it to be application/json.
- We retrieve the raw POST data from the php://input stream.
- We attempt to decode the contents of the POST data from JSON into a PHP associative array.
- We check to see if the result is an array. If it is not an array, then something has gone wrong. To debug the issue even further, be sure to check out this article on JSON error handling in PHP.
- After that, we can process the associative array.
Hopefully, you found this tutorial to be helpful!
Read JSON request data with PHP
While working on an API project, I realised that I actually didn’t know how to receive JSON data in the request body with PHP. Turns out it’s really simple with the php://input stream.
Most projects we work on with PHP rely on forms to receive data. That’s what the $_POST superglobal is for: it contains all information passed via HTTP POST when sending data with content type application/x-www-form-urlencoded or multipart/form-data .
But what if you use the application/json content type? Up until PHP 5.6 we could use the $HTTP_RAW_POST_DATA superglobal, but this has been deprecated. Instead we should use the php://input stream to read raw data from the request body.
Below is an example script. The comments explain what’s happening:
// Only allow POST requests if (strtoupper($_SERVER['REQUEST_METHOD']) != 'POST') < throw new Exception('Only POST requests are allowed'); > // Make sure Content-Type is application/json $content_type = isset($_SERVER['CONTENT_TYPE']) ? $_SERVER['CONTENT_TYPE'] : ''; if (stripos($content_type, 'application/json') === false) < throw new Exception('Content-Type must be application/json'); > // Read the input stream $body = file_get_contents("php://input"); // Decode the JSON object $object = json_decode($body, true); // Throw an exception if decoding failed if (!is_array($object)) < throw new Exception('Failed to decode JSON object'); > // Display the object print_r($object); Let’s give this a quick whirl. Save the example as script.php and start the standalone PHP server with php -S localhost:8080 script.php .
Now let’s send it a POST request containing JSON data using cURL:
curl -X POST \ -d '' \ -H "Content-Type: application/json" \ http://localhost:8080Your JSON object should be printed out:
Array ( [foo] => Array ( [0] => bar [1] => baz ) )