How to get PHP script to delete an object in JSON file?

Question

So I have an HTML file that is dynamically populated with information from a JSON file, with an ajax _POST request.

All I'm trying to do, is grab the json (just one simple array of objects), strip out the appropriate one via it's index number passed by the ajax, and then recode the JSON back into the same file. No errors, but nothing at all is happening.

Thanks!

Here is my ajax:

$(document).ajaxComplete(function(event, xhr, settings) {
        var json = "data/comments.json";
        $('.delete').click(function(index) {
            var deleteIndex = $(this).parent().attr('id');
            var deleteIndex = parseInt(deleteIndex);
            $.ajax({
                type: 'POST',
                url: 'data/save.php', // the url where we want to POST
                data: deleteIndex,
                success: function(){ 
                                        location.reload();
                                    },
                error: function(){    
                                        alert('Fail!');
                                    }
                });
        });
    });

and here is my PHP:

<?php
$data => $_POST['deleteIndex'];
$file = file_get_contents('comments.json');
$json[] = json_decode($file, true); //return an array
foreach($json as $key => $value) {
   if($value == $data) {
    unset($json[$data]);
    file_put_contents('comments.json', json_encode($json, JSON_PRETTY_PRINT));
   }
}
?>

that's hideously inefficient. why do you want to keep re-writing the json file on every loop iterating? read the json, decode it, manipulate the in-memory data, THEN write out the new json once you're done manipulating. — Marc B
– Marc B, Commented Oct 18, 2016 at 20:02
Why JSON_PRETTY_PRINT its code that is playing with the data, it does not need to be pretty — RiggsFolly
– RiggsFolly, Commented Oct 18, 2016 at 20:03

Dekel · Accepted Answer · 2016-10-18 20:28:25Z

1

You didn't set the name of the value you send to your server. The data key in the request should be a {key:val} object (or a url-formatted string).

    $(document).ajaxComplete(function(event, xhr, settings) {
    var json = "data/comments.json";
    $('.delete').click(function(index) {
        var deleteIndex = $(this).parent().attr('id');
        var deleteIndex = parseInt(deleteIndex);
        $.ajax({
            type: 'POST',
            url: 'data/save.php', // the url where we want to POST
            data: {'deleteIndex': deleteIndex},
            success: function(){ 
                location.reload();
            },
            error: function(){    
                alert('Fail!');
            }
        });
    });
});

In your PHP code I think this will be much better:

$data = $_POST['deleteIndex'];
$file = file_get_contents('comments.json');
$json = json_decode($file, true); //return an array

unset($json[$data]); // I guess you want to delete the value by key
file_put_contents('comments.json', json_encode($json));

answered Oct 18, 2016 at 20:28

Dekel

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5 Comments

Aeromax Over a year ago

I tried the above, and it's definetly passing something to the php script, but it's actually writing into the json file, rather than deleting anything.

Aeromax Over a year ago

What it writes in is

Aeromax Over a year ago

Ugh, SO noob here... it writes in a new JSON object with "NULL" for every entry.

Dekel Over a year ago

glad I could help :)

Aeromax Over a year ago

Nevermind I just figured out what it wasn't working. My screwup is too embarrassing to even mention.

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