$_POST variable empty when send POST

Question

I'm trying to send a JSON to my rest-api using RestSharp. Essentially I've created a model class for the json:

public class LogPostData
{
    public string LogMessage { get; set; }
    public string LogStackTrace { get; set; }
    public string LogUserId { get; set; }
    public string LogUserIp { get; set; }
}

so I perform the request in this way:

 var logPost = new LogPostData();
     logPost.LogMessage = "log message"
     logPost.LogStackTrace = "some content";

 var post = JsonConvert.SerializeObject(logPost);

 var client = new RestClient("url of rest api");

 var request = new RestRequest("methodApi", Method.PUT);
     request.RequestFormat = DataFormat.Json;
     request.AddParameter("application/json; charset=utf-8", post, ParameterType.RequestBody);
     request.RequestFormat = DataFormat.Json;

 var response = client.Execute(request);

as you can see I've created the object LogPostData and then serialized it using JsonConvert.SerializeObject.

I called the methodApi passing as parameter the json.

Now, inside my rest api, I did the following:

file_put_contents('debug.txt', serialize($_POST));

the content should be the variable that I sended with RestSharp on post variable, instead I get: a:0:{}

why my $_POST variable is empty?

@FirstOne so is not possible valorize $_POST using restsharp? — pivutali
– pivutali, Commented Nov 25, 2017 at 15:44
I don't know C#, let alone restsharp, so I'm not capable of answering that. Can't you change the PHP portion of the project? — FirstOne
– FirstOne, Commented Nov 25, 2017 at 15:48
@FirstOne if I change with php//input I get the content sended by php, but this should appear inside $_POST — pivutali
– pivutali, Commented Nov 25, 2017 at 15:49
@FirstOne you're right, but I remember when I using js in past and executed ajax.Post, the content will fill the php $_POST variable — pivutali
– pivutali, Commented Nov 25, 2017 at 15:59

Brian Rogers · Accepted Answer · 2017-11-25 17:27:07Z

4

According to the PHP manual, $_POST works with application/x-www-form-urlencoded and multipart/form-data content types. You are sending JSON (application/json). Since $_POST is an associative array created from posted form data, and you are not posting a form, it's not surprising that it would be empty.

To get the raw JSON from the request body you need to use php://input

$json = file_get_contents('php://input');

To deserialize the JSON to an object you can use json_decode.

$logPostData = json_decode($json);

If you want the data to be converted into an associative array like $_POST, you can pass true as the second parameter:

$logPostData = json_decode($json, true);

answered Nov 25, 2017 at 17:27

Brian Rogers

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5 Comments

pivutali Over a year ago

ok this seems to work just a question: why if I change the method of request to POST: Method.POST); I still get $_POST empty?

Brian Rogers Over a year ago

Because you are sending application/json not application/x-www-form-urlencoded

pivutali Over a year ago

I change in the php script the header and setted as: header('Content-Type: application/x-www-form-urlencoded'); I also change the request in c# as new RestRequest("methodApi", Method.POST); then I added as parameter this: ` request.AddParameter("application/x-www-form-urlencoded", post, ParameterType.RequestBody);` so I checked the content of $_POST with this: file_put_contents('debug.txt', serialize($_POST)); and I get this : a:0:{} what is wrong now?

Brian Rogers Over a year ago

If you change the content type to application/x-www-form-urlencoded, you have to actually send that type of content, i.e. url-encoded key-value pairs. You are sending JSON. They are different types of content. See Differences in application/json and application/x-www-form-urlencoded

pivutali Over a year ago

I got it, as I said I changed to application/json and when I do this:

$rawData = file_get_contents("php://input");     $json = json_decode(rawData, true);       file_put_contents('debug.txt', $rawData);

I get nothing inside the file

James · Accepted Answer · 2017-11-25 17:18:45Z

1

Here's what you are sending (JSON):

header: encoding-type=application/json
body: {"param1":"I like horses", "param2":"they are cool"}

This is what PHP needs in a POST request for the $_POST array to work (form submissions)

header: encoding-type=application/x-www-form-urlencoded
body: param1=I%20like%20horses&param2=they%20are%20cool

If you are happy with sending json, you need to receive it properly. If you want to keep using PUT, then make a handler for it that expects JSON. (Based on this answer)

$method = $_SERVER['REQUEST_METHOD'];
if ('PUT' === $method) {
    $data = json_decode(file_get_contents('php://input'), true);
    var_dump($data); //$data contains put fields 
}

answered Nov 25, 2017 at 17:18

James

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