Sending JSON from jQuery to PHP to edit a text file

Question

What I'm trying to do is the following: I want to send a JSON object from my jQuery code to the PHP file on my server. I want the PHP file to append this JSON object to my text file.

The problem:

I'm struggeling with the PHP file. I'm sending the data and I need the PHP to save that data in a variable so that I can write it into a textfile. The problem is that it doesn't do that. The post I make, apparently, has no content (it just shows array()).

My jQuery code:

var username = "";
var password = "";
var url = window.location.href;
var title = document.title;
var detailsArray = {title : [{
                    "title" : title,
                    "url" : url, 
                    "username" : username, 
                    "password" : password
                    }]
                    };

$(document).keydown(function(e) {
    if(e.which == 17) {
        console.log(detailsArray);
        $.ajax({
          type: "POST",
          url: "http://......./Server.php",
          data: detailsArray,
          success: function(data) {
              console.log("Data sent!"+data);
          }
        });
    }
});

My PHP code:

$dataToBeInserted = $_POST;
$file = "JSON.json";

//Open the file with read/write permission or show text
$fh = fopen($file, 'a+') or die("can't open file");
$stat = fstat($fh);

//Remove the last 2 characters from the JSON file
ftruncate($fh, $stat['size']-2);

//Add the data from $dataToBeInserted to the file
echo fwrite($file, $dataToBeInserted );

//Close the file
fclose($fh);

This PHP file gives a couple of warning/errors:

Array ( )

Warning: fwrite() expects parameter 1 to be resource, string given in Server.php on line 17

Warning: fwrite() expects parameter 1 to be resource, string given in Server.php on line 19

What am I doing wrong here? I'm not used to PHP so there's probably a bunch of errors in there, but I thought the jQuery side was okay.

Doesn't fwrite need $fh instead of file? php.net//manual/en/function.fwrite.php — dmgig
– dmgig, Commented Jun 6, 2014 at 18:06
In your ajax code block, try adding the option: dataType: 'json', (don't forget: the capital T in dataType, enclose json in quotes, the trailing comma) — cssyphus
– cssyphus, Commented Jun 6, 2014 at 18:18
@gibberish: I just tried that but it still gives the Array (). Im starting to think its the way I set up my detailsArray but Im not sure what I've done wrong there. — Brannie19
– Brannie19, Commented Jun 6, 2014 at 18:31
Scratch that, it must be something else. I just used the code xcezzz gave me and it's reading the JSON perfectly fine! This means I have something weird in my PHP file thats not supposed to be there, but I'll figure it out. Thank you for trying (and helping) :) — Brannie19
– Brannie19, Commented Jun 6, 2014 at 18:57

xxcezz · Accepted Answer · 2014-06-06 18:40:15Z

1

first your fwrite($file) should be fwrite($fh).. you have to write to the file handle returned by fopen... not the string name of the file.

$dataToBeInserted = $_POST;
$file = "JSON.json";

//Open the file with read/write permission or show text
$fh = fopen($file, 'a+') or die("can't open file");
$stat = fstat($fh);

//Remove the last 2 characters from the JSON file
ftruncate($fh, $stat['size']-2);

//Add the data from $dataToBeInserted to the file
echo fwrite($fh, $dataToBeInserted );

//Close the file
fclose($fh);

but then your JSON file is incomplete/corrupt. since you removed the 2 characters, but never added them back.

honestly the easy way to solve this would be

$data = json_decode(file_get_contents('JSON.json'));
if (!$data) $data = array();
array_push($data, $_POST);
file_put_contents('JSON.json', json_encode($data);

but this will get very expensive IO/resource wise the larger it gets

other method.... see comments

$dataToBeInserted = $_POST;
$file = "JSON.json";

//Open the file with read/write permission or show text
$fh = fopen($file, 'a+') or die("can't open file");
$stat = fstat($fh);

//Remove the last 2 characters from the JSON file
//ftruncate($fh, $stat['size']-2);

//Add the data from $dataToBeInserted to the file with a comma before it if there is data in file already.
if ($stat['size'] != 0) $append = ",";
echo fwrite($fh, $append . json_encode($dataToBeInserted) );

//Close the file
fclose($fh);

now to read it..

$data = file_get_contents('JSON.json');
$dataArray = json_decode('[' . $data  . ']');

so now each time we write to the file we put a comma, then when we read it we wrap it in brackets so it's an array of the writes we have been doing.

While this wont be as resource intensive write-wise it will be read wise... but thats because you want everything in one file.

edited Jun 6, 2014 at 18:40

answered Jun 6, 2014 at 18:06

xxcezz

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6 Comments

Brannie19 Over a year ago

You were right about the error message, $file was supposed to be $fh. The resources will be a problem eventually because the JSON file will end up being very long. Is there a (less) easy to do this?

xxcezz Over a year ago

That comes down to how will this data be used/loaded? Can you just dump each request to an individual file in a directory based off timestamp or date("Y-m-dH-i-s") type format? then there is no resource issue on a big ol file, but then how will the data be read back?

Brannie19 Over a year ago

I'm afraid not, it has to be in a single file. I'll eventually be doing things with Arduino, which has VERY limited resources.

xxcezz Over a year ago

well reading in a big ol file will still be a problem on that kind of platform... but I will update the answer with another way if you have control over the way it is read...

xxcezz Over a year ago

hope that all makes sense... this way it's mostly valid JSON in the file and just needs a bracket burrito to be read properly

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