Circular model dependencies with ruby on rails

Question

I'm trying to design the database model hierarchy and the migrations for my database for a group chat app and I'm new to rails so I'm quite confused about how I should build this... Any guidance would be greatly appreciated!

It breaks down as follows:

Groups <==> Users <==> Posts
Groups ==> Posts

So the groups have a bunch of users and users have a bunch of groups, but also the groups have the posts that the users make. Each post belongs to one group and one user. The post must also maintain a reference to the user that posted it.

Should I just make a joined table of all 3? Is that practical/efficient?

I'm just confused where I should use belongs_to , has_one , has_many , has_and_belongs_to_many and how I should write the migration files...

thanks for any help ahead of time

Answer 1

you can do it in next way

Groups

has_and_belongs_to_many :users
has_many :posts

Users

has_and_belongs_to_many :groups
has_many :posts

Posts

belongs_to :group
belongs_to :user

posts table should have group_id and user_id columns also create table groups_users migration:

class CreateGroupsUsers < ActiveRecord::Migration
  def change
    create_table :groups_users, id: false do |t|
      t.references :group, index: true
      t.references :user, index: true
    end
  end
end

This should work!

EDIT

for adding association between User and Group:

group = Group.create(name: 'New Group')
user = User.last
user.groups << group

or

user.build_group(name: 'New Group')
user.save

or you can use nested_attributes

User.create(params[:user])

where params[:user] = {user_name: 'James Bond', group_attributes: {name: 'New Group'}}