PHP: Get POST JSON

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My recent work at Mozilla has me creating an OAuth-like authentication transaction between Bugzilla and Phabricator.  This task has thrust me back into the world of PHP, a language I haven't touched much (since version ~5.2) outside of creating WordPress themes and plugins for this blog.  Coming back to a language you haven't touched in years feels like a completely new experience; you notice patterns and methods that you wouldn't have guessed of in years past.

Part of the authentication transaction requires Phabricator to receive a POST request that contains JSON data.  I had expected the data to land in $_POST but the variable was empty; how the hell do I get the POST data?  To get POST JSON with PHP, you use the following:

# Get JSON as a string
$json_str = file_get_contents('php://input');

# Get as an object
$json_obj = json_decode($json_str);

file_get_contents, which I though was only used to retrieve content from local files or traditional URLs, allows you to use the special php://input address to retrieve JSON data as a string.  From there you use json_decode to turn the JSON string into a workable object/array.

It makes sense that the JSON isn't handled via normal $_POST since there's really no key, per se; essentially you just need the "blob" of data as a whole, which is provided by php://input.  You can test the JSON+POST handling with cURL.

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Discussion

  1. Lorenzo

    I always use this line of code:

    @json_decode(($stream = fopen('php://input', 'r')) !== false ? stream_get_contents($stream) : "{}");

    It does not throw a warning in case there’s no request body, and simply fallback to an empty object instead of null.

  2. @David, you might want to merge $_POST and 'php://input'

    $_POST = array_merge($_POST, (array) json_decode(file_get_contents('php://input')));
  3. Jose Maria Ferri Azorin

    You say “It makes sense that the JSON isn’t handled via normal $_POST…” but I can’t find any sense since I’m using jQuery AJAX or XMLHttpResponse calls (POST) from many years ago, parsing parameters as json or plain text and parameters, in server, are where I expect they are: $_POST array… for me, using file_get_contents('php://input') is a non-logic behaviour

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