Question

I am wondering how the new and create method of TOPIC should look like, if TOPIC belongs to USER and FORUM.

class Forum < ActiveRecord::Base
  belongs_to :user
  has_many :topics, :dependent => :destroy
end

class User < ActiveRecord::Base
  has_many :forum
  has_many :topic
end

class Topic < ActiveRecord::Base
  belongs_to :user
  belongs_to :forum
end

When TOPIC belonged to only FORUM, I made use of build method like this.

def new
  @forum = Forum.find(params[:forum_id])
  @topic = @forum.topics.build
end

def create
  @forum = Forum.find(params[:forum_id])
  @topic = @forum.topics.build(params[:topic])
  if @topic.save
    flash[:success] = "Success!"
    redirect_to topic_posts_path(@topic)
  else
    render 'new'
  end
end

But now that TOPIC belongs to both FORUM and USER, I am not sure what to do? Any suggestions on this topic?

Here’s my schema for reference. Ignore POST for now.

create_table "forums", :force => true do |t|
  t.datetime "created_at",  :null => false
  t.datetime "updated_at",  :null => false
  t.string   "name"
  t.text     "description"
  t.integer  "user_id"
end

create_table "posts", :force => true do |t|
  t.datetime "created_at", :null => false
  t.datetime "updated_at", :null => false
  t.integer  "topic_id"
  t.text     "content"
  t.integer  "user_id"
end

create_table "topics", :force => true do |t|
  t.datetime "created_at",   :null => false
  t.datetime "updated_at",   :null => false
  t.integer  "forum_id"
  t.string   "name"
  t.integer  "last_post_id"
  t.integer  "views"
  t.integer  "user_id"
end

create_table "users", :force => true do |t|
  t.string   "name"
  t.string   "email"
  t.datetime "created_at",                         :null => false
  t.datetime "updated_at",                         :null => false
  t.string   "password_digest"
  t.string   "remember_token"
  t.boolean  "admin",           :default => false
end

---

My solution to new create method

def create
  @forum = Forum.find(params[:forum_id])
  @topic = @forum.topics.build(params[:topic])
  @topic.user_id = current_user.id

  if @topic.save
    flash[:success] = "Success!"
    redirect_to topic_posts_path(@topic)
  else
    render 'new'
  end
end

current_user returns current user object.

Answer 1

topic = Topic.new
topic.forum = Forum.first
topic.user = User.first

topic = Topic.create(:forum => Forum.first, :user => User.first)

topic = @user.topics.build(params[:topic])
topic.forum = @forum

etc