Validation

Hi folks,

I have one question about this issue.
I have a structure as follow: one table user with field name, city and other, and another table client that is some attributes and this table is belongs_to :user, until here...its ok.
The problem is that field city is requeried to add a new user, but when i got to add a new client, is not possible.
I made some test and saw that problem is at validate_presence_of in models/user.rb.
What do I have to add at models/client.rb to fix this.

Thanks for help me.