multi-step.rb

#<a href="http://ow.ly/18z1T">RoR Multi-step forms</a>

private
    def get_partial_user_from_session
      unless @session['partial_user'].nil?
        @user = @session['partial_user']
      else
        @user = User.new
      end
    end

    def save_partial_user_in_session
      unless @user.nil?
        @session['partial_user'] = @user
      end
    end
    
    # Might be a good addition to AR::Base
    def valid_for_attributes( model, attributes )
      unless model.valid?
        errors = model.errors
        our_errors = Array.new
        errors.each { |attr,error|
          if attributes.include? attr
            our_errors << [attr,error]
          end
        }
        errors.clear
        our_errors.each { |attr,error| errors.add(attr,error) }
        return false unless errors.empty?
      end
      return true
    end


#To ensure the errors are cleared out properly on each request add a before_filter with the following:
    def clear_stage_errors
      unless @session['partial_user'].nil?
        @session['partial_user'].errors.clear
      end
    end

=begin
You can use
get_partial_user_from_session
and
save_partial_user_in_session
as before and after filters, respectively, so you only have to reference @user in your multi-step controller.
=end

#A clean way to arrange the view is to have each step in its own partial, and set a variable such as
@current_stage
#in your controller, then in your view just do something like:
<%= start_form_tag({:action=> "signup"} , { :name => 'signupform' }) %>
<%= hidden_field_tag "changeCountry" %>
<%= hidden_field_tag "current_stage", "#{@current_stage}"%>

<h2>Registration Process</h2>
<%= @flash['notice'] %>

<%= render_partial "#{@current_stage}" %>
	
<%= end_form_tag %>


#Your signup controller action could something similar to this:
  def signup
    case @request.method
      when :post
        @current_stage = @params['current_stage']
        if @current_stage == "stage1"
          @user.attributes = @params['user']    
            @current_stage = "stage2" if valid_for_attributes(@user,["login","attribute2"])
          end
        elsif @current_stage == "stage2"
          @user.attributes = @params['user']    
          @current_stage = "stage3" if valid_for_attributes(@user,["attribute3","attribute4"])
        elsif @current_stage == "stage3"
          @user.attributes = @params['user']
          
          if @user.save
            @session[:user] = User.authenticate(@user.login, @params['user']['password'])
            flash['notice']  = "Signup successful"
            redirect_to :action => "home"
          end
        end
      when :get
        @current_stage = "stage1"
    end
  end



#==========================================
=begin
Comments on this post
bmarini posts on May 19, 2008 at 12:56
I took your partial validation idea and included it in AR Base
=end
module ActiveRecord
  module Validations
    module Partial
      def valid_for_attributes?( *attr_names )
        return validate_for_attributes(attr_names)
      end
      
      def validate_for_attributes( *attr_names )
        attr_names.map! {|a| a.to_s }
        
        unless valid?
          our_errors = Array.new
          errors.each { |attr,error|
            if attr_names.include? attr
              our_errors << [attr,error]
            end
          }
          
          errors.clear
          our_errors.each { |attr,error| errors.add(attr,error) }
          return false unless errors.empty?
        end
        return true
      end
        
    end
  end
end

ActiveRecord::Base.class_eval do
  include ActiveRecord::Validations::Partial
end

=begin
cgunther posts on Jul 02, 2009 at 11:40
bmarini, I think there is a bug in your code.

When I called:
=end
@order.valid_for_attributes? 'first_name', 'last_name'

=begin
It always passed validation. The error was the asterisk in front of attr_names on validate_for_attributes. It was being passed an array as the first attribute and when you run map! on it, it was converting the entire array to a single string (first_namelast_name).

Here's the code that works for me:
=end
module ActiveRecord
  module Validations
    module Partial
      def valid_for_attributes?( *attr_names )
        return validate_for_attributes(attr_names)
      end
      
      def validate_for_attributes( attr_names )
        attr_names.map! {|a| a.to_s }
        
        unless valid?
          our_errors = Array.new
          errors.each { |attr,error|
            if attr_names.include? attr
              our_errors << [attr,error]
            end
          }
          
          errors.clear
          our_errors.each { |attr,error| errors.add(attr,error) }
          return false unless errors.empty?
        end
        return true
      end
        
    end
  end
end

ActiveRecord::Base.class_eval do
  include ActiveRecord::Validations::Partial
end


#The main difference is that if you call validate_for_attributes directly, you have to pass it an array.

#Chris Gunther