Embed a Rails form partial into another page - ruby-on-rails

Question

I'm building a rails 4.2.0 app with a contact us page (this page does have a semi-empty controller). I'm trying to embed a form partial from another controller.
Here is the code (minus the text):
<% if user_signed_in? %>
<% render 'enquiries/form' %>
<% end %>
When I run this I get the error 'First argument in form cannot contain nil or be empty'.
My enquiries form looks like a basic rails form:
<%= form_for #enquiry do |f| %>
<% if #enquiry.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#enquiry.errors.count, "error") %> prohibited this enquiry from being saved:</h2>
<ul>
<% #enquiry.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :subject, "Subject:" %><br>
<%= f.text_field :subject %>
</div>
<div class="field">
<%= f.label :e_description, "Description:" %><br>
<%= f.text_area :e_description %>
</div>
<div class="actions">
<%= f.submit %>
</div>
What could be the possible reason for the error? Or is there a better way of embedding a view into another?
Update/Edit:
Here's the routes:
devise_for :users
resources :rooms do
resources :viewings
end
resources :rmcats
resources :extras
resources :extracats
resources :enquiries
root :to => redirect('/pages/home')
get 'pages/home'
get 'pages/contactus'
And the enquiry controller:
class EnquiriesController < ApplicationController
before_action :set_enquiry, only: [:show, :edit, :update, :destroy]
# GET /enquiries
def index
#enquiries = Enquiry.all
end
# GET /enquiries/1
def show
end
# GET /enquiries/new
def new
#enquiry = Enquiry.new
end
# GET /enquiries/1/edit
def edit
end
# POST /enquiries
def create
#enquiry = Enquiry.new(enquiry_params)
if #enquiry.save
redirect_to #enquiry, notice: 'Enquiry was successfully created.'
else
render :new
end
end
# PATCH/PUT /enquiries/1
def update
if #enquiry.update(enquiry_params)
redirect_to #enquiry, notice: 'Enquiry was successfully updated.'
else
render :edit
end
end
# DELETE /enquiries/1
def destroy
#enquiry.destroy
redirect_to enquiries_url, notice: 'Enquiry was successfully destroyed.'
end
private
# Use callbacks to share common setup or constraints between actions.
def set_enquiry
#enquiry = Enquiry.find(params[:id])
end
# Only allow a trusted parameter "white list" through.
def enquiry_params
params.require(:enquiry).permit(:subject, :e_description)
end
end
This is the pages controller:
class PagesController < ApplicationController
around_filter :resource_not_found
# def home
# end
private
# If resource not found redirect to root and flash error.
# => For pages this will rarely be needed as it should 404.
def resource_not_found
yield
rescue ActiveRecord::RecordNotFound
redirect_to root_url, :notice => "Page not found."
end
end
Edit:
Log:
Started GET "/pages/contactus" for ::1 at 2015-03-21 01:05:25 +0000
Processing by EnquiriesController#new as HTML
[1m[35mUser Load (0.0ms)[0m SELECT "users".* FROM "users" WHERE "users"."id" = ? ORDER BY "users"."id" ASC LIMIT 1 [["id", 1]]
Rendered enquiries/_form.html.erb (0.0ms)
Rendered pages/contactus.html.erb within layouts/application (0.0ms)
Completed 200 OK in 235ms (Views: 234.6ms | ActiveRecord: 0.0ms)

Answer 1

It is telling you that #enquiry is nil at the time it is trying to render the form. You need to call the new action to create the #enqiury for the form to represent.
You could change your route to:
get 'pages/contactus' => 'enquiries#new'
Then in your Enquiry controller:
def new
#enquiry = Enquiry.new
render 'pages/contactus'
end
EDIT:
Ok, so now we combine what Friends Systems put in his answer:
<% if user_signed_in? %>
<%= render 'enquiries/form' enquiry: #enquiry %>
<% end %>
And now change any instance of #enquiry in the form to enquiry
This is because you need to pass the variable to the partial.

Answer 2

the problem is, that your #enquiry variable is not defined in the context you are rendering the partial.
its not defined by the controller action that gets called, you should create a instance of Enquiry by calling
#enquiry = Enquiry.new
in your action.
In Addition
to use it somewhere else i would pass the #enquiry instance variable as a locale variable to the partial
<% render 'enquiries/form', :enquiry => #enquiry %>
your form method should then look like this:
<%= form_for enquiry do |f| %>
...
<% end %>
of course all the instances vars should be replaced then. just remove the '#'
EDIT:
According to your controller setup you posted above the best way would be to use something like
#enquiry ||= Enquiry.new
in your form partial to make shure a new instance is created if #enquiry is nil.