[RESOLVED] Process changed fields in a form

[damiantaylor]

Hi,
I am experimenting with processing forms and have written a simple form that has a checkbox and a text box.

I have found some php code that lets me process only the checked check boxes but I can't do the same thing for text boxes.
Is there a way to process only the text boxes where the user has changed the contents?

My HTML form is as follows:

<form method="post" action="update.php" />
<table class="splfTable">
<tr class="tableDetail">
<td><input type="checkbox" name="delete[]" value="DEL1"></td>
<td><input name="job[]" value="JOB1" type="text"></td>
</tr>
<tr class="tableDetail">
<td><input type="checkbox" name="delete[]" value="DEL2"></td>
<td><input name="job[]" value="JOB2" type="text"></td>
</tr>
<tr class="tableDetail">
<td><input type="checkbox" name="delete[]" value="DEL3"></td>
<td><input name="job[]" value="JOB3" type="text"></td>
</tr>
</table>
<input type="submit" name="update" value="update" />
</form>

My php code update.php that processes the checkboxes is:

// Check which checkboxes have been checked
if ($_POST['update']){
   if ( isset($_POST['delete']) ) { 
      foreach($_POST['delete'] as $key => $val){
         echo $key . ' ' . $val;
      }
   }
}

When I do the above for 'job' rather than 'delete' I just get all 3 textboxes rather than just the one I have typed in to on the form.

I hope I'm making sense!

Thanks for taking a look 🙂

[Ashley_Sheridan]

The reason for that is that the browser only sends checkbox and radio button values if they are selected, but if a text box exists, it is always sent, even if empty.

What you need to do is inside your loop, perform an extra check to see if the field is empty (assuming that empty is your non-changed state)

if ($_POST['update'])
{
   if ( isset($_POST['delete']) )
   {
      foreach($_POST['delete'] as $key => $val)
      {
         if($val == '')
         {
            echo $key . ' ' . $val;
         }
      }
   }
}

[bradgrafelman]

You can use id's inside of the [] brackets to associate a checkbox with a textbox, e.g.:

td><input type="checkbox" name="delete[]" value="1"></td>
<td><input name="job[1]" value="JOB1" type="text"></td>
</tr>
<tr class="tableDetail">
<td><input type="checkbox" name="delete[]" value="2"></td>
<td><input name="job[2]" value="JOB2" type="text"></td>

You'd then use these id's like so:

foreach($_POST['delete'] as $job_id) {
   if(isset($_POST['job'][$job_id]) && $_POST['job'][$job_id] != '')
      do_something_with($_POST['job'][$job_id]);
   else
      echo "Error: You didn't fill in the textbox #$job_id - oops!<br>\n";
}

[Ashley_Sheridan]

bradgrafelman, that might not be too flexible though. I'm guessing from the example given that this form will grow larger and contain variable content, which might prove problematic if all the fields require a specific index in order to be handled by PHP.

[bradgrafelman]

Ashley Sheridan;10944879 wrote:

bradgrafelman, that might not be too flexible though. I'm guessing from the example given that this form will grow larger and contain variable content, which might prove problematic if all the fields require a specific index in order to be handled by PHP.

I'd considered that, and forgot to mention the alternative. If you're careful with your form fields, then you can let PHP auto-index the array and use those indexes instead. New example:

td><input type="checkbox" name="delete[]" value="1"></td>
<td><input name="job[]" value="JOB1" type="text"></td>
</tr>
<tr class="tableDetail">
<td><input type="checkbox" name="delete[]" value="2"></td>
<td><input name="job[]" value="JOB2" type="text"></td>

EDIT: I'm stupid and wasn't thinking about the behavior of checkboxes. Oopsie. :o

EDIT2: Wait a minute... I think I missed the OP's question altogether.

@: You're wanting to only process the textboxes that you have changed from their default value (e.g. the one you specified in the HTML)?

If so, you'll have to do some more work so that PHP can identify these textboxes. How is PHP supposed to know if a textbox was changed or not - all it knows is what values you POST to it.

Two easy solutions for this are: 1) sessions, and 2) hidden form fields. For a session, you'd store the default value in the session for each textbox and when the form is submitted, loop through each textbox and see if the value POST'ed matches the one in the session - if not, then process the change.

For the hidden form fields, you'd do the same thing except you compare the textbox's value to the corresponding hidden form field's value (which, presumably, the user wouldn't alter).

Here's an example using hidden form fields:

<tr class="tableDetail">
<td><input type="checkbox" name="delete[]" value="DEL1"></td>
<td><input name="job[]" value="JOB1" type="text">
 <input name="job_prev[]" value="JOB1" type="hidden"></td>
</tr>

and then to process it:

foreach($_POST['job'] as $id => $value) {
    if(isset($_POST['job_prev'][$id])) {
        if($value != $_POST['job_prev'][$id]) {
            // textbox value (a.k.a. $value) was changed! process it here
        }
    } else {
        // something went wrong... no matching default value was found in job_prev
        // perhaps the user maliciously altered the form to try and break your script?
    }

[damiantaylor]

Sorry for getting back to you all so late, I posted my question just before I finished work yesterday.
Thanks to everyone who responded. Your replies certainly helped a lot.

I think I'll use the hidden fields method as it seems the easiest to implement.

Thanks again for all your help guys!!!