Get variables from a POST Method without HTML form

Question

I want to pass javascript variables (without form) to php, so php can write them in a textfile on the server-side. For this, I'm using this jQuery line:

$.post( "http://localhost/main.php", data);

Here is the php:

$data = $_POST['data'];
echo $data;

$file = "test.txt"
$handle = fopen($file, 'w');
fwrite($handle, $data);
fclose($handle);

I think the problem could be the 'data' tag, when I try to access the information in php, but I don't know what should I put there since all the examples that I found was associated with html forms.

The other thing tho', which I don't really understand is: I do this whole thing on a button-click, so if I click the button, it posts to the php, but does that actually run the above php code, and writes in the text file or am I missing something?

*btw, I use WAMP for PHP, but I don't think it matters.

@SatishGupta They are using [AJAX](http://api.jquery.com/jQuery.post/) ... — Teemu, Feb 25 '18 at 13:35
var data = { hours: 0, mins: 0, secs: 0, tenths: 0 }; but it is incremented before I pass it. on var_dump($_POST) gives back: array (size=0) empty — hotigeftas, Feb 25 '18 at 13:38
I'm not trying to send the actual time, but an arbitrary one. so its just a simple object with 4 properties. — hotigeftas, Feb 25 '18 at 13:47

score 1 · Answer 1 · answered Feb 25 '18 at 13:56

Post data is submitted in key/value pairs. For your payload that's:

hours => 0, mins => 0, secs => 0, tenths => 0

After the POST request PHP has this data inside of the $_POST associative array. To access hours for example you'd write $hours = $_POST["hours"]. If you want to write the data to the text file you now need to tell PHP what the file should look like:

<?php
$hours = $_POST["hours"],
$mins = $_POST["mins"]
.
.
.

$fileDataToWrite = "Hours: ".$hours." Minutes: ".$mins // and so on

This variable can now be passed to the fwrite function as the second parameter:

$file = "test.txt"
$handle = fopen($file, 'w');
fwrite($handle, $fileDataToWrite);
fclose($handle);

The resulting file would then look like this:

Hours: 0 Minutes: 0

You can choose how you want the file to look like, or if you for example want it to be in JSON format by simply changing how you build the $fileDataToWrite variable.

In your JS code you should add a callback for when the PHP has ran on the server side:

$.post("http://localhost/main.php", data, 
    response => console.log("Time saved on the server!"));

The php page keeps throwing "unidentified index: hours" to this line: $hours = $_POST["hours"]; and for the others as well. Do you have a guess why is it happening? — hotigeftas, Feb 25 '18 at 14:23

score 1 · Accepted Answer · answered Feb 25 '18 at 14:01

1

Semi-Copying my answer from here

PHP is kind of interesting in that it doesn't pull from $_POST like other forms when Ajax is involved. You actually will need to read the input from php://input

Here is a tiny example

$data = file_get_contents("php://input");
$response = json_decode($data, true ); // True converts to array; blank converts to object

$emailAddr = $response["hour"];

Hopefully you can apply that successfully.

While debugging this I would highly recommend using Chrome's Developer mode with the 'network' tab. Find your ajax call near the bottom and you can view exact header info.

answered Feb 25 '18 at 14:01

John Pavek

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Thank you for your answer. When I send the POST request, I can console out this on the client-side: Time saved on the server!{"hours":"00","mins":"00","secs":"01","tenths":"2"}. Then the PHP gets the request, as I can see it in the headers, and it also has 200 status code. Then I try to var-dump it, and it says: C:\wamp64\www\phpsandbox\timePlusPlus\main.php:4:string '' (length=0). The code looks like this: $data = file_get_contents("php://input"); var_dump($data); Do you have any idea, why this happening? Note, that on client-side it says POST, but on the server it says it's a GET. – hotigeftas Feb 27 '18 at 23:39
@hotigeftas if Php is reading it as empty it's likely the request isn't coming through properly, I would watch the network tab as you submit this and see how the headers look, and ensure the data object is passing properly. – John Pavek Feb 28 '18 at 14:02

Get variables from a POST Method without HTML form

2 Answers2