How to validate form_for elemets together with form_tag elements?

Question

I have a form_for form to which I added custom fields using *_tag methods.

For normal form_for elements I have validation inside the model, however I am not sure what should I do with my text_field_tag elements.

What would be the most elegant way to validate those fields?

Code update:

<%= form_for(@member, :html => {:class => "generic-form"}) do |f| %>
    <% if @member.errors.any? %>
        <div id="error_explanation">
            <h2><%= pluralize(@member.errors.count, "error") %> prohibited this member from being saved:</h2>
        <ul>
            <% @member.errors.full_messages.each do |msg| %>
            <li><%= msg %></li>
    <% end %>
        </ul>
    </div>
  <% end %>
  <%= f.label :username, "Username:" %>
  <%= f.text_field :username %>
  <%= f.label :password, "Password:" %>
  <%= f.password_field :password %>
  <%= label_tag "repeatPassword", "Repeat password:" %>
  <%= password_field_tag "repeatPassword" %>
  <%= f.label :email, "Email:" %>
  <%= f.text_field :email %>
  <button type="submit" name="commit">Register</button>
<% end %>

Answer 1

I guess you have an action which update/create a Member instance. In this action you could do something like this:

def update
  [...]
  if params[:repeatPassword] == params[:member][:password]
    @member.save
  else
    @member.errors.add('password', 'Passwords werent the same')
    redirect_to :action => :update, :id => params[:id]
  end
  [...]
end

Hope this Helps!