CodeIgniter highlight fields with errors on form submission - php

Question

I could use some guidance in how to proceed on form validation in CodeIgniter. I am using CodeIgniter's built-in form validation and works fine as far as it goes. It returns individual error messages for each field where there is an error by using and wrapping it in some HTML/CSS for styling:
<?php echo validation_errors('<p class="error">'); ?>
But what we want to do is highlight the fields where there are errors. CI will let you put the error messages next to where the form errors are. But it requires you to use the error message for the value, like this:
<input type="text" name="email" value="<?php echo set_value('email'); ?>" size="50" />
which by the way is in CI's manual in non-CI syntax, which puzzles me. Anyway, we also want the data from the field when the form is submitted to be preserved and returns. So I've done:
$email = array('name' => 'email', 'value' => $em);
?><div style="padding:5px;">Email* </div><?php echo form_input($email) . '<br/>';
$em is returned from the controller like this:
$data['em'] = $this->input->post('email');
So my question is, how do I accomplish all of what is outlined above? Obviously, what CI suggests and what I have done collide. But I don't know how else to do it, so I could use some help.
EDIT: Upon further digging, I see that you can put the error message next to the field by doing this:
<?php echo form_error('email'); ?>
But I'm not getting any message upon an error, even though I have the rule written and I get an error with the first line of code above.

Answer 1

form error($field) returns an empty string '' so better use:
<input type="text" name="email" <?php if (form_error($email) !=='') { echo 'class="error"'; } ?> value="<?php echo set_value('email'); ?>" size="50" />
Tested.

Answer 2

In order to display error individually you should use the function form_error('email'). And for you to get a value of a field being checked, use the function set_value('email'). For these two functions to work, you would have had to, in your controller, set a rule for the 'email' field. Where you specify wich validation rules apply to that field.
<?php echo form_error('email'); ?>
<input type="text" name="username" value="<?php echo set_value('email'); ?>" size="50" />
source: http://codeigniter.com/user_guide/libraries/form_validation.html#individualerrors

Answer 3

untested, but form_error($field) should return true if there is an error:
So perhaps:
<input type="text" name="email" <?php if (form_error($email)) { echo 'class="error"'; } ?> value="<?php echo set_value('email'); ?>" size="50" />
untested. worth a shot?
Perhaps also consider using JQuery or similiar to validate and style the form fields, and use CI as a fallback (for presentation purposes, obviously).
That way your form validation can be styled as you required without CI limitations for 99% of validation rules, and then anything else, the default CI way can kick in.