JavaScript - POST to URL not sending data

Question

I'm trying to send POST data from a Chrome extension to a website controlled by me. However, when sending the POST data I don't receive any.

I'm sending it using this function:

async function httpPost(url, data) {
    const response = await fetch(url, {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(data)
    });
    return response.json();
}

It is being called like so:

const post = await httpPost("https://example.com/api", extracted);

Where extracted contains something similar to {entries: [], total: 0 }.

I've tried console.log on httpPost, response, post which did not gave anything useful besides that they're working correct.

On the server side, doing a isset for $_POST does work. The request is sending and is being received. However, doing file_put_contents('test.txt', print_r($_POST)); leaves the file empty. It is being accessed, just empty.

CORS Headers are set:

header("Access-Control-Allow-Credentials: true");
header("Access-Control-Max-Age: 1000");
header("Access-Control-Allow-Headers: X-Requested-With, Content-Type, Origin, Cache-Control, Pragma, Authorization, Accept, Accept-Encoding");
header("Access-Control-Allow-Methods: *");
header('Content-Type: application/json');

What could this very frustrating issue be?

Desired output: Being able to receive the POST data that I sent with httpPost.

ADyson · Accepted Answer · 2021-02-04T15:47:10.737

1

See https://www.php.net/manual/en/function.print-r.php - if you want to capture the output of print_r into a string (so you can write it to a file, for example!) You need to set the return parameter, as noted in the documentation. Right now that's probably just printing the post variables back into the AJAX response, instead of into the file.

E.g. try this:

file_put_contents('test.txt', print_r($_POST, true));

Edit:

Since you're actually sending JSON in the request, none of the above is particularly applicable anyway.

Similar to the answer in Receive JSON POST with PHP

you would read in the JSON data into a string, like this:

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

Now, to process this in general, you'd run json_decode() on it to turn it into a PHP variable (object, or array depending on the exact content and your preference). But if you simply want to write this data into a file, you might as well just write the raw JSON directly, so you could simply do this:

file_put_contents('test.txt', $json);

edited Feb 04 '21 at 15:47

answered Feb 04 '21 at 15:04

ADyson

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Hi, thanks for the answer. This does indeed work for the printing part - text.txt now contains an empty array: `Array()`. However, it does not contain any post data, that I send using the fetch? – Appel Flap Feb 04 '21 at 15:31
Actually, I just noticed you're sending JSON from the client. In PHP you need to read incoming JSON differently than you do with regular form data. See https://stackoverflow.com/questions/18866571/receive-json-post-with-php for how to do that. (P.S. If all you want to do is write the JSON data direct to the file without processing it, there's probably no point in running json_decode on it, you could just write the raw string direct.) – ADyson Feb 04 '21 at 15:43
Ah. Thanks for pointing that out. Would've never figured it out otherwise. Thanks a ton. – Appel Flap Feb 04 '21 at 15:50

JavaScript - POST to URL not sending data

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