Checkbox Array

[Guest]

Hi

I am having a problem with a form/update database page.

I use a while loop to print a form for all the photos listed in a table - with their names/descriptions and the user must check a checkbox if he/she would like to include the photo in the main gallery. All goes OK except for my checkbox system.

I think the problem lies in that the checkbox array won't make a blank element if the checkbox has not been checked. ie. if I check the 20th and 30th photo's then the array will still think this to be the 1st and 2nd. I need to force the new array elements in the unchecked records so that on the update form I could use a conditional to set the values in the database. Can anyone see my problem? Thanks for any help. Chris

FORM:

while ($row = mysqli_fetch_array($r)) {

           echo '<div class="photo-thumb">

<img src="../upload/' . rawurlencode($row['PhotoName']) . '" height="80px" />

<a href="delete_photo.php?id=' . $row['PhotoID'] . '&photoname=' . $row['PhotoName'] . '">Delete</a>

<p>' . $row['PhotoName'] . '</p>';

if ($row['Gallery'] == 1) {echo '<p>Photo Gallery: <input name="Gallery[]" id="Gallery" type="checkbox" value="1" checked="checked" /></p>';}

else {echo '<p>Photo Gallery: <input name="Gallery[]" id="Gallery" type="checkbox" value="1"/></p>';}

echo '<p>Description: <input name="PhotoDescription[]" id="PhotoDescription" type="text"  maxlength="80" value="' . $row['PhotoDescription'] . '" /></p>

<input name="PhotoID[]" id="PhotoID" type="hidden" value="' . $row['PhotoID'] . '" />';

echo '</div>';

}

UPDATE PAGE:

<?php  

$query = "SELECT * FROM photos";

$result = mysqli_query($dbc, $query);

$Total = count($_POST['PhotoID']);

for ($i = -1; $i <= $Total; $i++)

{

$PhotoDescription = $_POST['PhotoDescription'][$i];

$PhotoDescription = mysqli_real_escape_string($dbc, $PhotoDescription);

$PhotoID = $_POST['PhotoID'][$i];

if (!isset($_POST['Gallery'][$i])) {$Gallery = 0;}

else {$Gallery = 1;}

$q = "UPDATE photos SET PhotoDescription=\"$PhotoDescription\", Gallery='$Gallery' WHERE PhotoID=\"$PhotoID\"";

$r = mysqli_query($dbc, $q);

}

?>

[David_Powers]

I can see a couple of ways of handling this.

The simplest is to use a pair of radio buttons instead of a checkbox, and make the "don't include" option the default. As long as one radio button is always selected, the value will appear in the array.

The alternative would be to use a counter in the while loop in your form.

$thumb = 1;

while ($row = mysqli_fetch_array($r)) {

  // inside the loop set the value of the checkbox to $thumb

  // increment the counter at the end of the loop

  $thumb++;

}

The value of each checkbox will then be a number. As you go through your update loop, you need to check the number:

if (isset($_POST['Gallery'][$i]) && $_POST['Gallery'] == $i + 1) {

    $Gallery = 1;

} else {

    $Gallery = 0;

}

[David_Powers]

Hang on. That second one won't work. I need to think about it a little more.

[David_Powers]

I think this should work:

if (isset($_POST['Gallery']) && in_array($i+1, $_POST['Gallery'])) {

    $Gallery = 1;

} else {

    $Gallery = 0;

}

This checks whether the Gallery array exists, and if it contains the current loop number + 1. You need to add the 1 because the while loop begins at 1.

[Guest]

Hi David,

Thanks for your replies.

I'll give this a go and get back to you.

Many thanks,

Chris

[Guest]

ahh still having a lot of problems. I'm a bit confused with your advice here though. I don't see how the $thumb variable changes anything with regard to the update page?

Sorry 😕 Thanks

[David_Powers]

The problem with checkbox groups is that a value is included in the $_POST array only if the checkbox is selected. So, setting the value of the checkbox to 1 to indicate that it has been selected is meaningless. You need to know which checkbox has been selected.

Using the $thumb variable as a counter in the loop will create a series of checkboxes each with a different value. The first will be 1, the second 2, the third 3, and so on.

You can then use the values in the $_POST['Gallery'] subarray to update your database. If $_POST['Gallery'] contains 5, 6, 7, 9, and 21, those are the records that need to add 1 to the database to indicate inclusion in the main gallery.

I started the $thumb counter at 1, but your update loop will begin at 0, so you need to check if $i+1 is in the $_POST['Gallery'] subarray.

[Guest]

Thanks, David.

You have helped me a lot but I just managed to work out a slightly different way, though inspired by yours, that you might agree is simpler and I can't believe how I never thought of it before. We don't need to use the $thumb counter and then search the $thumb array. Instead I just did the same thing but with the photo's id!! How simple!

I put the value of the checkbox as the Photo's ID and on the update script's loop I just asked if the $PhotoID variable was in the $Gallery array. It works perfectly.

Thank you,

Chris

[David_Powers]

Sounds like a good idea. As long as you have a value to identify the selected item, that's what matters. Using an existing value is certainly better than creating another one.