Flutter http.post sending empty body

Question

I have a problem when I try to send data to a web service. It seems that the $_POST[ ] variable in the php file doesn't receive the content of the body of the http.post request in Flutter.

In Flutter, I use the following code :

var url = 'https://www.xxx';
var headers = {
  "Content-Type": "application/json",
};
var requestBody = json.encode(
    { 'pays': infoPays, 'societe': infoSociete, });

final http.Response response = await http.post(
    url,
    body: requestBody,
    headers: headers);
print(headers);
print(requestBody);
print(response.statusCode);

and my php file (web service) is the following :

<?php
//Header
header('Content-type: application/json');

//Connexion à la DB
try {
  $bdd = new PDO('xxx');

} catch (\Exception $e) {
  die('Erreur : '.$e->getMessage());
}
echo $_POST["pays"];

//Lecture du POST
$pays = isset($_POST["pays"])? htmlspecialchars($_POST["pays"]): "";
$societe = isset($_POST["societe"])? htmlspecialchars($_POST["societe"]): "";
$datetime = date ('Y-m-d H:i:s');

//Insertion des données
$req = $bdd->prepare("INSERT INTO Informations (pays, societe,  info_date) values (?,?,?)");
$execute = $req->execute(array($pays, $societe, $datetime));

if ($execute) {
    $responseArray = array(
        'status' => 'true',
        'message' => 'All data have been successfully stored.'
    );
} else {
    $responseArray = array(
        'status' => 'false',
        'message' => 'Error happened when storing data.'
    );
}
echo json_encode($responseArray);
 ?>

In my DB I see that there is a new record (including the time stamp) and I receive a status code 200 proving that it works as it should but the data that the php file is supposed to receive from the Flutter http request (the body, I assume) are empty. It is proven by the echo of the $_POST["pays"] variable that shows nothing.

It seems thus that the $_POST[ ] variable in the php file doesn't receive the content of the body of the http.post request in Flutter.

Could you help me, please? I don't see what's wrong in the code (I must confess I am not a professional developper).

Many thanks !

Bernard

Huthaifa Muayyad · Accepted Answer · 2021-03-20 15:02:50Z

2

It's something with your php code, the Dart code works fine, as the post request is successful, proven by the new entry in your database.

But since the entry is empty and only has a timestamp, it means that it's not populating your DB fields.

Thus, there is flaw between php and DB, as it is not interpreting or you are not extracting the data correctly. Not a php expert, so can't point out exactly where the problem is, but it's not Flutter\Dart.

I don't see that you are decoding the response from the post body before echoing it or storing it. Decoding the body should help.

Cheers

edited Mar 20, 2021 at 15:02

answered Mar 20, 2021 at 13:14

Huthaifa Muayyad

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4 Comments

Bernard Over a year ago

Thanks for your answer ! I think the problem is the interaction between the http.post request and the $_POST[ ] variable in php, the http.post not populating the $_POST[ ] variable. I just don't see why.

Huthaifa Muayyad Over a year ago

Hey Bernard, I don't see that you are decoding the response from the post body before echoing it or storing it. Hopefully a php developer will come along and point out the issue.

Bernard Over a year ago

Great, it has to be decoded ! I added this line : $_POST = json_decode(file_get_contents('php://input'), true); and it works ! Many thanks Huthaifa !

Huthaifa Muayyad Over a year ago

Great to hear that! Kindly mark this an 'answer' since it solved the issue. You're most welcome Bernard!

Mirwais Shah Arya · Accepted Answer · 2024-01-07 16:36:17Z

When you use http.post in Dart with a JSON-encoded body, the data is sent as a raw POST body, not as traditional $_POST data in PHP. This means that the $_POST array in PHP will be empty because it only parses data sent with a content type of application/x-www-form-urlencoded.

To fix this, you need to modify your PHP script to read the raw POST data and decode it from JSON. Here's how you can do it:

  // Read the raw POST data from the input stream
  $rawData = file_get_contents("php://input");
  $jsonData = json_decode($rawData, true);

  echo $jsonData; //the is the data that you send using your API

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