On CodeIgniter, how to repopulate a form only with correct values? - forms

Question

Imagine a form like this:
<form action="test.php" method="post">
<input type="text" name="firstname" value="<?=set_value('firstname')?>" />
<input type="text" name="lastname" value="<?=set_value('lastname')?>" />
<input type="text" name="email" value="<?=set_value('email')?>" />
<input type="submit" name="submit_form" value="OK" />
</form>
If I submit an incorrect email, the CodeIgniter function will write "the field is not valid" and populate the invalid field with the wrong value.
I would like to keep the error message but not the wrong value (I prefer having an empty value). But I also want to keep the re-populating function for correct values.
Here is what I get:
Here is what I want:
[EDIT] SOLUTION FOUND (thanks to Herr Kaleun and Matt Moore)
Example with the email field:
<input type="text" name="email" id="email" value="<?=!form_error('email')?set_value('email'):''?>" />

Answer 1

You can check the fields individually and have a logic like this.
If the error for a specific field is present, you can build a logic on top of that.
if ( form_error('email') != '' )
{
$data['email_value'] = '';
}
else
{
$data['email_value'] = set_value('email');
}
<form action="test.php" method="post">
<input type="text" name="firstname" value="<?=set_value('firstname')?>" />
<input type="text" name="lastname" value="<?=set_value('lastname')?>" />
<input type="text" name="email" value="<?= $email_value; ?>" />
<input type="submit" name="submit_form" value="OK" />
</form>

Answer 2

The Form_error is set when a form value errors out based on the validation. Judging by your use of the set_value function I assume you're using the built in form validation. You can check to see if the message for that field is set if(form_error('fieldname') !=NULL) and set the value based on that.
You may have to setup error messages for each field, which you should be doing anyway. Here is the guide that covers it: http://codeigniter.com/user_guide/libraries/form_validation.html#repopulatingform
<form action="test.php" method="post">
<input type="text" name="firstname" value="<?if(form_error('firstname') != NULL){echo set_value('firstname');}?>" />
<input type="text" name="lastname" value="<?if(form_error('lastname') != NULL){ echo set_value('lastname');}?>" />
<input type="text" name="email" value="<?if(form_error('email') !=NULL){ echo set_value('email');}?>" />
<input type="submit" name="submit_form" value="OK" />
</form>
*NOTE THIS CODE HAS NOT BEEN TESTED *