Placing Forums within Categories (Rails 4) - ruby-on-rails

Question

I am in the process of creating a forum using Ruby on Rails (I'm pretty new at this) and have managed to get myself utterly stuck.
**Version Ruby on Rails 4.0 **
A forum software can have many Categories, and within these Categories you can have multiple forums.
The main page would look similar to this:
Category 1
Forum 1
Forum 2
Category 2
Forum 3
Forum 4
Forum 5
When you create a forum, you should have a drop down menu that allows you to select which category you wish to place it in.
At first I created two different scaffolds- One for Categories and one for Forums. I used a foreign key to connect the two. I do not know if this is the best method, but I could not get them to interact at all. I ended up screwing up my code so badly I have very little to show for it.
I tried using Adding Sub-categories in Rails4 and categories and sub-categories model rails for solutions but both ended up causing errors.
Here is some of my code. It's not much, but maybe you can tell me where to even begin. If there is a better way of doing this (not using two tables), let me know. I would love to hear the best possible way of doing this without using gems
WARNING: my code is an utter mess.
Migration
class AddForeignToForums < ActiveRecord::Migration
def change
add_column :forums, :category_id, :integer
end
end
Forum Controller (I know I am missing something that will allow me to connect to the Category, I just don't know what)
class ForumsController < ApplicationController
before_action :set_forum, only: [:show, :edit, :update, :destroy]
# GET function. view/forums/index.html.erb
def index
#forums = Forum.all
end
# GET /forums/1. view/forums/show.html.erb
def show
#forum = Forum.find(params[:id])
end
# GET /forums/new. view/forums/new.html.erb
# Be able to list all the Categories.
def new
#forum = Forum.new
#categories = Category.all
end
# GET /forums/1/edit
# Be able to list all the categories.
def edit
#forum = Forum.find(params[:id])
#categories = Category.all
end
# POST /forums
# Allows the creation of a new forum
# Lindsey note: how to save category_idea. Assign to category.
def create
#forum = Forum.new(forum_params)
respond_to do |format|
if #forum.save
#forum = Forum.new(:name => params[:forum][:name],
:category_id => params[:forum][:category_id])
format.html { redirect_to #forum, notice: 'Forum was successfully created.' }
format.json { render action: 'show', status: :created, location: #forum }
else
format.html { render action: 'new' }
format.json { render json: #forum.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /forums/1
# Allows the update of forums.
def update
respond_to do |format|
if #forum.update(forum_params)
format.html { redirect_to #forum, notice: 'Forum was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: 'edit' }
format.json { render json: #forum.errors, status: :unprocessable_entity }
end
end
end
# DELETE /forums/1
def destroy
#forum.destroy
respond_to do |format|
format.html { redirect_to forums_url }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_forum
#forum = Forum.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def forum_params
params.require(:forum).permit(:name, :description, :category_id)
end
end
Forum Model
class Forum < ActiveRecord::Base
belongs_to :category
end
Category Model
class Category < ActiveRecord::Base
has_many :forums, :dependent => :destroy,
end
Category Index.html.erb
<tbody>
<% #categories.each do |category| %>
<tr>
<td><%= link_to category.name, category %></td>
<td><%= link_to ' (Edit', edit_category_path(category) %></td>
<td><%= link_to '| Destroy)', category, method: :delete, data: { confirm: 'Are you sure?' } %></td>
</tr>
<% category.forums.each do |forum| %>
<tr>
<td><li><%= link_to forum.name, forum %></li></td>
</tr>
<% end %>
<% end %>
</tbody>
Forum _form.html.erb
<%= form_for(#forum) do |f| %>
<div class="field">
<%= f.label :name %><br>
<%= f.text_field :name %>
</div>
<div class="field">
<%= f.label :description %><br>
<%= f.text_area :description %>
</div>
<%= f.label :category_id %><br />
<%= f.select :category_id, Category.all.map{|c| [c.name, c.id]} %>
<div class="actions">
<%= f.submit %>
</div>

Answer 1

You probably want a table for forums, a table for categories, and a join table that includes a forum_id and category_id - name this forum_categories
class Forum < ActiveRecord::Base
has_many :forum_categories
has_many :categories, :through => :forum_categories
end
And, with categories, you'll do the reverse
class Categories < ActiveRecord::Base
has_many :forum_categories
has_many :forums, :through => :forum_categories
end
For adding categories in the view, you can use checkboxes or a multiple select box. The name of this input will be either
f.check_box 'category_ids[]'
or
f.select 'category_ids[]'
This will submit a param in an array format that will allow you to update the forum.category_ids with a simple
forum.create(params[:forum])
In your view, instead of #forums, you'll list category.forums
<% category.forums.each do |forum| %>
<%= forum.name %>
<% end %>
Hopefully this will get you started.
EDIT
For a single category on Forum, you've done well. Just a few smaller changes:
class Category < ActiveRecord::Base
# belongs_to :category - this can be removed
has_many :forums # Do you want to delete the forums if the category is removed? You don't need the classname option.
end
In the drop down - you'll do something like this...
f.select :category_id, Category.all.map{|c| [c.name, c.id]}