I have an User model. It has next fields:

```rb
attr_accessible :user_name, :first_name, :last_name, :email ....

```

There is a profile view for the User with 6 blocks. Each of them associated with the various fields. Box 1 - **first\_name** and **last\_name**, Box 2 - **user\_name** and **email**, etc.

I need to validate all the fields (presence, format, etc). But validators must trigger only for those fields, that has came from a particular block (Box 1 or Box 2, for example). 

If I write something like next:

```
validates :user_name, :presence => true

```

and I will not edit the block with the \*user\_name\*, I will see the error "user Name can't be blank". I can't use \*:allow\_blank => true\* or nil because it can't(!) be blank!

In two words: I must validate only those fields, that was past from the resquest.

What I can do to solve my problem? Thx