[fw-general] Zend_Form add custom error messages

[Andries Seutens]

Hi,

I can't seem to be able to figure out how I can add custom errors to 
certain error decorators of the form.

Take for instance that I have a user signup, where the username field 
has to be unique. When the user enters a username which already exists 
in the database, I'd like to push an error to the decorator of the 
username field.

Is this only possible with a custom validator?

Best,

Andriesss