Rails form_for own action routes - ruby

Question

I want to modify the action (submit) for a form_for helper
<%= form_for(#rating, :as => :post, :url => demo_create_rating_path(#rating)) do |f| %>
<div class="field">
<%= f.label :value %><br />
<%= f.select :value, %w(1 2 3 4 5) %>
</div>
<%= f.hidden_field :article_id, :value => #article.id%>
<%= f.hidden_field :user_id, :value => current_user.id %>
<div class="field">
<%= f.label :description %><br />
<%= f.text_area :description, size: "100x5" %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
This is my View and it does not work.
All I want is, that I can redirekt the Action after submit button but then a get this error:
ActionController::RoutingError (No route matches {:controller=>"demo_ratings", :action=>"create", :article_id=>#<Rating id: nil, value: nil, description: nil, article_id: nil, user_id: nil, created_at: nil, updated_at: nil>}):
app/views/demo_ratings/_form.html.erb:1:in `_app_views_demo_ratings__form_html_erb__1912848844925280312_70155649546120'
app/views/demo_ratings/new.html.erb:13:in `_app_views_demo_ratings_new_html_erb__27525029454473720_70155632487040'
What am I doing wrong?
UPDATE
All my funktion that are need by form_for helper:
def new
#rating = Rating.new
#article = Article.find(params[:article_id])
end
def edit
#rating = Rating.find(params[:id])
#article = Article.find(params[:article_id])
end
def create
#rating = Rating.new(params[:rating])
if #rating.save
#article= Article.find(params[:article_id])
puts #article.name
puts #rating.id
#rating.article = #article
puts #rating.article.name
redirect_to demo_rating_path(#rating, :article_id => #article.id), notice: 'Rating was successfully created.'
else
render action: "new"
end
end
def update
#rating = Rating.find(params[:id])
if #rating.update_attributes(params[:rating])
#article = #rating.article
redirect_to demo_rating_path(#rating), notice: 'Rating was successfully updated.'
else
render action: "edit"
end
end

Answer 1

Try this:
<%= form_for(#rating, :as => :post, :url => demo_create_rating_path) do |f| %>
The #rating in the url is providing a nil object id, and you don't have an id yet.
If you want to share the form between create and update, then use the following:
<% form_for(#rating, :as => :post) do |f| %>
For reference, review the output of a rails generated scaffold's _form.html.erb.
In your controller, your are saving the new/ updated record before your processing. The statement if #rating.save should come after #rating.article = #article.
def create
#rating = Rating.new(params[:post])
#article= Article.find(params[:article_id])
#rating.article_id = #article.id
if #rating.save
redirect_to demo_rating_path(#rating, :article_id => #article.id), notice: 'Rating was successfully created.'
else
render action: "new"
end
end