get value of checkbox submit to a variable - php

Question

I'm trying to work out how to get the value of a checkbox submit it to a variable which is an id from a sql db.
Below is my current code:
-- Index.php
<?php
$sql = "SELECT * FROM `file`";
if (!$result = $db->query($sql)){
die('There was an error running the query [' . $db->error . ']');
}
?>
<form method="post">
<button class="btn btn-success">New</button>
<button type="submit" class="btn btn-warning">Edit</button>
<button class="btn btn-danger">Delete</button>
<table class="table table-condensed">
<thead>
<th>#</th>
<th>Name</th>
<th>Category</th>
<th>Date</th>
</thead>
<tbody>
<?php while($row = $result->fetch_assoc()){ ?>
<td><input type="checkbox" name="id_grab" value="<?php echo $row['file_id']; ?>"></td>
<td><?php echo $row['file_name']; ?></td>
<td><?php echo $row['file_category']; ?></td>
<td><?php echo date('d-m-y', strtotime($row['file_date'])); ?></td>
</tbody>
<?php } ?>
</table>
</form>
-- file_edit.php
<?php include('../db_connect.php') ;
$id=isset($_POST['id_grab']);
$sql = "SELECT * FROM `file` WHERE file_id = $id";
if (!$result = $db->query($sql)){
die('There was an error running the query [' . $db->error . ']');
}
$row = $result->fetch_assoc();
?>
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true">× </button>
<h4 class="modal-title" id="myModalLabel">Edit Invoice / Receipt</h4>
</div>
<div class="modal-body">
<form action="../includes/file_update.php" method="post" role="form" enctype="multipart/form-data">
<div class="form-group">
<label for="File_Name">Name</label>
<input type="text" name="file_name" class="form-control" id="file_name" value="<?php echo $row['file_name']; ?>">
</div>
<div class="form-group">
<lable for="File_Category">Category</label>
<input type="text" name="file_category" class="form-control" id="file_category" placeholder="Financial">
</div>
<div class="form-group">
<label for="file_tag">Tag</label>
<input type="text" name="file_tag" class="form-control" id="file_tag" placeholder="statement">
</div>
<div class="form-group">
<label for="file_description">Description</label>
<input type="text" name="file_description" class="form-control" id="file_description">
</div>
<div class="form-group">
<label for="file_date">Date</label>
<input type="date" name="file_date" class="form-control" id="file_date">
</div>
<div class="form-group">
<label for="file_location">File</label>
<input type="file" class="form-control" name="file_location" value="file">
<p class="help-block">Select appropriate file for upload.</p>
</div>
<button type="button" class="btn btn-info" data-dismiss="modal">Cancel</button>
<button type="submit" class="btn btn-success">Upload</button>
</form>
</div>
I can't work it out, spent hours looking online... My concern is at it's using Bootstraps Modal I wasn't sure if it would be able to grat the POST data... As if I enter the ID manually it works...
Any assistance would be greatly appreciated.

Answer 1

change this
$id=isset($_POST['id_grab']);
to
$id=isset($_POST['id_grab'])?$_POST['id_grab']:'';
//if id_grab dont have a value then $id value will be ''
isset() Returns TRUE if var exists and has value other than NULL, FALSE otherwise.