如何防止更改预设的INPUT值？

Question

I have a form where some fields are completed by loading information from a database. These fields can vary from one account to another.

When the form is submitted any database information will be sent along with new information entered in the form.

However, the user is able to change (on screen) the information entered from the database, and although these changes are not submitted (my $Xvariables from the database override the POSTed $variables), I would like them to revert the on-screen data back to the database value.

Here is an example of what I have at the moment, but it does not work ...

  <input type="text" name="firstname" size="25" tabindex="4" onchange="if($xfirstname<>'') this.value=$xfirstname" value="<?php echo $firstname;?>"/>

or better still, if there is a way, how can I make them unchangable if they have a value loaded from the database ?

Answer 1

Keep this:

<input type="text" name="firstname" size="25" tabindex="4"
 value="<?php echo $firstname;?>"/>

Add this: Edit: Sorry did not see it has no ID on the input element use this:

<script>
if($('input[name="firstname"]').val().length > 0)
{
$('input[name="firstname"]').attr("disabled", true);
}
</script>

Result :http://jsfiddle.net/4wt9r/6/

But keep in mind anything on the client can be changed, your true filtering/authenticating must be done on the server.