Specifiying attributes on the join model of a has_many :through

rubyonrails-core
1

Hey list,

I was wondering on the definitive approach of setting attributes on
the join model of a has_many :through relation. After some googling, I
didn't find a "shortcut" approach to it, so I started tinkering, and
thinking. Imagine users, groups, and memberships. Would something like this be a
good approach?

group.members << :user => @user, :role => Role.admin

If so, I could whip up a patch. If not, please enlighten me as to what
would be a good way to assign those properties.

cheers, bartz

2

The generally accepted way of doig this is to start thinking of a membership as a first_class entity.

When you 'sign up', for example, you are creating a membership.

Membership.create :user_id => params[:user_id], :group_id => params[:group_id], :joined_on => Date.today, :active => true

I have found that there is seldom a reason to take an extra DB hit to grab one or both related objects. In fact, I'd argue that

@user = User.find_by_id(1) @group = Group.find_by_id(1) @group.members << @user

is a waste of objects and a waste of time. However, if you have both objects already, simply assign them.

Membership.create :user => @user, :group => @group, :joined_on => Date.today, :active => true

Does that make sense?

3

The generally accepted way of doig this is to start thinking of a membership as a first_class entity.

When you 'sign up', for example, you are creating a membership.

Membership.create :user_id => params[:user_id], :group_id => params[:group_id], :joined_on => Date.today, :active => true

I have found that there is seldom a reason to take an extra DB hit to grab one or both related objects. In fact, I'd argue that

@user = User.find_by_id(1) @group = Group.find_by_id(1) @group.members << @user

is a waste of objects and a waste of time. However, if you have both objects already, simply assign them.

Membership.create :user => @user, :group => @group, :joined_on => Date.today, :active => true

Does that make sense?

That does make sense, and I do agree :). However, in a GroupsController.create, with a current_user, wouldn't
it be easy to do something like

def create    @group = Group.new(params[:group)    if @group.save && @group.users << current_user, :role => Role.admin    # etc end

cheers, bartz