has_and_belongs_to_many association in rails 4 - associations

Question

I've done everything as in here http://guides.rubyonrails.org/association_basics.html#the-has-and-belongs-to-many-association, but it doesn't work. I found some answers in stackoverflow, but still it doesn't work. I've made association for posters and types. But when I specify the type of the poster nothing happens. There is no adding to DB, and no types in the Poster's view. Here is my PostrsTypes creating table:
class PostersTypes < ActiveRecord::Migration
def change
create_table :posters_types, id: false do |t|
t.integer :poster_id
t.integer :type_id
end
add_index :posters_types, [:poster_id, :type_id]
end
end
Here is Poster model:
class Poster < ActiveRecord::Base
has_and_belongs_to_many :types
belongs_to :user
validates :title, :body, :publish_date, :user_id, :presence => true
end
And Type model:
class Type < ActiveRecord::Base
has_and_belongs_to_many :posters
validates :name, :presence => true
end
Any ideas why nothing is writing in the DB?
EDIT. That's my posters_controller, if you need it:
class PostersController < ApplicationController
before_action :set_poster, only: [:show, :edit, :update, :destroy]
before_filter :authenticate_user!, :except => :index
# GET /posters
# GET /posters.json
def index
#posters = Poster.all
end
# GET /posters/1
# GET /posters/1.json
def show
end
# GET /posters/new
def new
#poster = Poster.new
end
# GET /posters/1/edit
def edit
end
# POST /posters
# POST /posters.json
def create
#poster = Poster.new(poster_params)
#poster.user_id = current_user.id
respond_to do |format|
if #poster.save
format.html { redirect_to #poster, notice: 'Poster was successfully created.' }
format.json { render action: 'show', status: :created, location: #poster }
else
format.html { render action: 'new' }
format.json { render json: #poster.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /posters/1
# PATCH/PUT /posters/1.json
def update
respond_to do |format|
if #poster.update(poster_params)
format.html { redirect_to #poster, notice: 'Poster was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: 'edit' }
format.json { render json: #poster.errors, status: :unprocessable_entity }
end
end
end
# DELETE /posters/1
# DELETE /posters/1.json
def destroy
#poster.destroy
respond_to do |format|
format.html { redirect_to posters_url }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_poster
#poster = Poster.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def poster_params
params.require(:poster).permit(:title, :body, :publish_date, :type_ids)
end
end

Answer 1

try using :type_ids=>[]
def poster_params
params.require(:poster).permit(:title, :body, :publish_date,:type_ids=>[])
end
This worked for me

Answer 2

So you've got your #poster now. After you call .save on it, it either saves, or it puts some errors in your model. Check your validations, and output them e.g. with #poster.errors (in your new-action, since this one is rendered if the save fails) and see what's wrong.