How to post JSON to PHP with curl

108
votes

I may be way off base, but I've been trying all afternoon to run the curl post command in this recess PHP framework tutorial. What I don't understand is how is PHP supposed to interpret my POST, it always comes up as an empty array. 

curl -i -X POST -d '{"screencast":{"subject":"tools"}}'  \
      http://localhost:3570/index.php/trainingServer/screencast.json

(The slash in there is just to make me not look like an idiot, but I executed this from windows using PHP 5.2, also tried on a Linux server, same version with Linux curl)

There must be something I'm missing because it seems pretty straightforward, the post just isn't be interpreted right, if it was, everything would work great.

This is what I get back:

HTTP/1.1 409 Conflict
Date: Fri, 01 May 2009 22:03:00 GMT
Server: Apache/2.2.8 (Win32) PHP/5.2.6
X-Powered-By: PHP/5.2.6
Transfer-Encoding: chunked
Content-Type: text/html; charset=iso-8859-1

{"screencast":{"id":null,"subject":null,"body":null,
         "dataUrl":null,"dataMedium":null,"createdOn":null,"author":null}}
5
phprestpost
Could you please copy-paste your .php file as well? Are you sure that the URL localhost:3570/index.php/trainingServer/screencast.json runs your script? It doesn't look like a PHP URL. – pts
@pts; Peter is using an MVC framework of some kind, take a look at index.php in that URL. – Alan Storm
@pts I'm using Delphi for PHP (hence the :3570) and the Recess MVC framework w/out .htaccess file, hence the index.php/ in the url. – Peter Turner
Don’t forget to send it as application/json. – Gumbo
Its not necessary to escape the double quotes when embedding them in simple ones. – user435996

5 Answers

107
votes

Jordans analysis of why the $_POST-array isn't populated is correct. However, you can use

$data = file_get_contents("php://input");

to just retrieve the http body and handle it yourself. See PHP input/output streams.

From a protocol perspective this is actually more correct, since you're not really processing http multipart form data anyway. Also, use application/json as content-type when posting your request.

120
votes

Normally the parameter -d is interpreted as form-encoded. You need the -H parameter: 

curl -v -H "Content-Type: application/json" -X POST -d '{"screencast":{"subject":"tools"}}' \
http://localhost:3570/index.php/trainingServer/screencast.json
18
votes

I believe you are getting an empty array because PHP is expecting the posted data to be in a Querystring format (key=value&key1=value1).

Try changing your curl request to:

curl -i -X POST -d 'json={"screencast":{"subject":"tools"}}'  \
      http://localhost:3570/index.php/trainingServer/screencast.json

and see if that helps any.

13
votes

You need to set a few extra flags so that curl sends the data as JSON.

command

$ curl -H "Content-Type: application/json" \
       -X POST \
       -d '{"JSON": "HERE"}' \
       http://localhost:3000/api/url

flags

  • -H: custom header, next argument is expected to be header
  • -X: custom HTTP verb, next argument is expected to be verb
  • -d: sends the next argument as data in an HTTP POST request

resources

1
votes

You should escape the quotes like this:

curl -i -X POST -d '{\"screencast\":{\"subject\":\"tools\"}}'  \
  http://localhost:3570/index.php/trainingServer/screencast.json