Create 'groups' that users can join, what would be a good approach?

I want to build "groups" that users can join, The flow of steps and things needed is in my head but the code to build thi开发者_StackOverflow社区s lacks some bit since I'm still learning rails. I would like to ask some advice on your ideas best practice of what would be needed to accomplish below:

• You can create a group with a name 'test'
• You automatically join the group test, other users can join to
• If want to see a list of the users joined my group 'test'

Im thinking of creating a model sessions like groups|name| But then how could I store the multiple users that are in this session? Should I make an array of the user_id's for example and make an extra column like groups|name|user_ids ?

What would be best practice and what rails (3) methods could I use to get a very rough version of the above functionality up and running ?

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From what I understand this is a many to many relationship. So you would have 3 models :

class User < AR
  has_many :memberships
  has_many :groups, :through => :memberships
end

class Membership < AR
  belongs_to :user
  belongs_to :group
end

class Group < AR
  has_many :memberships
  has_many :users, :through => :memberships
end

and to know what users belong to a group :

@group = Group.find_by_name("test")
@users_group = @group.users

Update

to ensure the user creating the group also belongs to it :

# in group_controller.rb
def create
  @group = Group.new(params[:group])
  @group.users << current_user

  if @group.save
    # ... etc
  end
end

of course the current_user should exist/be logged in with the usual before_filter (if I remember correctly its authenticate! with devise)

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Sorry i'm creating a new thread, but I am unable to comment as of my new status right now.

@charlysisto your answer for this question involves a User, Membership, and Group class. I understand the need of User and Group, but I am confused to why we would need a Membership class. If anything doesn't it make more sense to have a Groups class with Group?

    class User < AR
    belongs_to :group
    belongs_to :groups, :through => :group
    end

    class Groups < AR
    has_many :groups
    has_many :users, :through => :group
    end

    class Group < AR
    has_many :users
    belongs_to :groups
    end

What do you think?