Question

I have these two controllers about stories and categories and they work alone. Now I want to add choosing a already created category when I add news. How should I connect them and how should I show all categories in new.html.erb with select tag?

class StoriesController < ApplicationController
  def index
    @stories = Story.all
  end

  def show
    @story = Story.find(params[:id])
  end

  def new
    @story = Story.new
  end

  def create
    @story = Story.new(params[:story])

    if @story.save
      redirect_to stories_path, :notice => "Your story was saved"
    else
      render "new"
    end
  end

  def edit
    @story = Story.find(params[:id])
  end

  def update
    @story = Story.find(params[:id])

    if @story.update_attributes(params[:story])
      redirect_to stories_path, :notice => "Your story has been updated"
    else
      render "edit"
    end
  end

  def destroy
    @story = Story.find(params[:id])
    @story.destroy
    redirect_to stories_path, :notice => "Your story has been deleted"
  end
end

class CategoriesController < ApplicationController
  def index
    @categories = Category.all
  end

  def new
    @category = Category.new
  end

  def create
    @category = Category.new(params[:category])

    if @category.save
      redirect_to categories_path, :notice => "Your category was saved"
    else
      render "new"
    end
  end

  def edit
    @category = Category.find(params[:id])
  end

  def update
    @category = Category.find(params[:id])

    if @category.update_attributes(params[:category])
      redirect_to categories_path, :notice => "Your category has been updated"
    else
      render "edit"
    end
  end

  def destroy
    @category = Category.find(params[:id])
    @category.destroy
    redirect_to categories_path, :notice => "Your category has been deleted"
  end
end

Answer 1

You could try with:

# app/controllers/stories_controller.rb
def new
  @categories = Category.all
  @story = Story.new
end

# app/views/stories/_form.html.erb
<%= form_for @story do |f| %>
  #....
  <%= f.collection_select :category_id, @categories, :id, :title %>