param getting passed as nil in Rails form

Question

I have a form where I am trying to do a very simple CRUD operations on rails with MongoDB.

I have my controller

class RecipesController < ApplicationController   
  def new
    @recipe = Recipe.new
  end

  def update
  end

  def create
    recipe = Recipe.create(params[:title])
    redirect_to params[:title]
    @recipes = Recipe.all
  end

  def index 
    @recipes = Recipe.all
  end
end

my form

<%= form_for Recipe.new do |f| -%>

<%= f.text_field :title %>

<%= f.submit "Create Recipe" %>

<% end %>

seems pretty basic to me. However, the params are not getting through to the controller it seems.

I can see the params passed through webrick

Started POST "/recipes" for 127.0.0.1 at 2010-09-02 14:15:56 -0800
  Processing by RecipesController#create as HTML
  Parameters: {"authenticity_token"=>"8oyq+sQCAEp9Pv864UHDoL3TTU5SdOXQ6hDHU3cIlM
Y=", "recipe"=>{"title"=>"test"}, "commit"=>"Create Recipe"}
Rendered recipes/create.html.erb within layouts/application (4.0ms)
Completed 200 OK in 51ms (Views: 16.0ms)

but the redirect_to params[:title] returns a nil value error.

I noticed that 'title' is inside the 'recipe' parameter, and wasn't sure if that may be part of the issue.

One of the the many things that has me confused is that I never actually have to call create? Is that right? I'm calling 'new' on the form, and for some reason rails automatically calls 'create'?

Answer 1

Try putting the redirect in your controller after @recipes = Recipe.all like so, and making your variables and instance variable :

def create
  @recipe = Recipe.new(params[:title])
  @recipes = Recipe.all
  respond_to do |format|
    if @recipe.save
      format.html redirect_to params[:title]
    end
  end
end

Your syntax is fairly ugly. I would suggest using the out-of-the-box Rails generators to scaffold your work, and base your project off of that until you get good at what you do.

Rails 2:

script/generate scaffold Recipe name:string ingredients:text

Rails 3:

rails g scaffold Recipe name:string ingredients:text

Then make sure you rake db:migrate

Answer 2

As you suggest the title parameter is inside your recipe set of parameters. So, to create your recipe you need to do:

Recipe.create(params[:recipe])

NB. this will return false and not create a recipe if the validations on the recipe fail - e.g. if you require a title. You don't check for this and you might want to.

So, similarly, if you want to redirect the title of the new recipe (I have no idea why you'd want to as that probably isn't a valid location but I'll go along with your example), you need to do:

redirect_to params[:recipe][:title]

or you can access the title on the newly created recipe r.title.

Also, if you are redirecting to another action there is no benefit in setting up instance variables (@recipes) as they will be lost during the redirect.