Tomas -
An *option* I've used in the past is to add a datetime field such as
"dropped_at" that defaults to null to your memberships table.
>From there, you could add a scope to the memberships model like:
class Membership < ActiveRecord::Base
scope :active, -> { where(dropped_at: nil) }
end
This concept used to be used when you wanted to "soft delete" a record from
your table,
but have an option to "undo" the delete. Here, in your instance - you can
borrow the idea
to easily find those memberships for a given User that are "active" as well
as those users
that are currently a part of a group. The standard created_at field that
is on the memberships
table can be used to indicate when a user joined a group.
Hope this helps!
Mike
On Tuesday, November 25, 2014 9:27:27 AM UTC-5, Tomas wrote:
>
> Hello,
>
> This is a classic User -> Membership -> Group example with some twist:
> User is a member of a single Group at any given time. But I want to keep
> the history which Group the User was a member of.
>
> I am looking for a proper way of doing it.
>
> This is how I think models should look like:
> #user.rb
> Class User < ActiveRecord::Base
> has_many :memberships
> has_many :groups, through: :memberships
>
> #membership.rb
> Class Membership < ActiveRecord::Base
> belongs_to :user
> belongs_to :group
>
> #group.rb
> Class Group < ActiveRecord::Base
> has_many :memberships
> has_many :users, through: :memberships
>
> Obviously we need date_from attribute in memberships to keep a track on
> when the user joined the group.
>
> Creating/Updating is working out of the box. It's querying data I have
> trouble with.
>
> Now it is easy to get the last group the user is a member of:
> #user.rb
> ...
> def latest_group
> memberships.order(:date_from).last.group
> end
>
> Similarly you can get latest user for a group.
>
> But how to get all users currently belonging to group? Furthermore how to
> get all the users belonging to group at given date?
>
> Looking forward for your input.
>
> Cheers
> Tomas
>
>
--
You received this message because you are subscribed to the Google Groups "Ruby
on Rails: Talk" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/rubyonrails-talk/ea111ac3-9c3d-4958-a7ce-65e8f86e7f88%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
