Pass model between controllers and views in Ruby on Rails - ruby-on-rails

Question

I have signup form on my home screen. If user inputs invalid data I redirect him to /signin page. On this page I can see filled fields, but errors descriptions are empty.
Here is my UsersController:
class UsersController < ApplicationController
def new
#user = User.new(params[:user])
end
def create
#user = User.new(params[:user])
print #user
if #user.save
else
render 'new'
end
end
end
Method I use to show errors
module ApplicationHelper
def errors_for(model, attribute)
if model.errors[attribute].present?
content_tag :div, :class => 'well error' do
content_tag :ul do
model.errors[attribute].collect {|item| concat(content_tag(:li, item))}
end
end
end
end
end
My form partial:
<%= f.label :user_name %>
<%= f.text_field :user_name, :class=>"input-medium" %>
<%= errors_for(#user, :user_name) %>
<%= f.label :email %>
<%= f.text_field :email, :class=>"input-medium " %>
<%= errors_for(#user, :email) %>
<%= f.label :password %>
<%= f.password_field :password, :class=>"input-medium" %>
<%= f.label :password_confirmation, "Confirmation" %>
<%= f.password_field :password_confirmation, :class=>"input-medium" %>
and my signup view:
<section class="centered user-form-container">
<div class="user-form well pull-left">
<div class="centered">
<h1>Sign up</h1>
<%= form_for(#user, :action=>"create") do |f| %>
<%= render 'signup', :f=>f %>
<%= f.submit "Sign up" %>
<% end %>
</div>
</div>
</section>

Answer 1

In this situation, I believe you need to use flash.now, something like this:
Per the rails docs:
By default, adding values to the flash will make them available to the next request, but sometimes you may want to access those values in the same request. For example, if the create action fails to save a resource and you render the new template directly, that’s not going to result in a new request, but you may still want to display a message using the flash. To do this, you can use flash.now in the same way you use the normal flash:
def create
#user = User.new(params[:user])
print #user
if #user.save
else
# start with this, then expand the error text
flash.now[:error] = "Could not save user"
render 'new'
end
end

Answer 2

You would do this in your validation method.
If you are using a standard rails validation you would do this:
validates_presence_of :foo, :message => 'Message you want to display here'
If you are doing a custom validation then this:
def my_validation_method
begin
my_validation_code_here
rescue
self.errors[:base] << 'Message you want to display here'
end
end

Answer 3

def new
#user = User.new(params[:user])
if (!params[:user].nil?)
#user.valid?
end
end