Question

I have groups (Group model) in my app, which represent groups of people.
I want each group to have its own forum.

Should I just have the forum id in the groups table? It doesn’t feel right. If I did it myself, the forum would have a polymorphic association to a “forumable” element (groups in this case, but I have other models that would need a forum).

Any opinions on what I should do? Modify the gem to fit my needs, or just have the forum_id in my models that need a forum? Or another solution maybe?

Answer 1

I’m the guy who started Forem (its the volunteers who did most of the hard work, though!), I think I can answer this question.

If you want only certain groups to have access to one and only one forum then you can put the forum_id field on the groups table and do it that way. What you can do then is override the can_read_forem_forum? method in your User model to perform a permission check for that user:

def can_read_forem_forum?(forum)
  groups.where(:forum_id => forum.id).any?
end

This is used in Forem’s ability model to determine whether or not a person can access a forum. What this method is going to do is that it will only return groups for that user that have link that specific forum. If there are any, then it’s known that the user can access that forum.

Now if you’re going the other route where a group may have access to many forums, well then you’d define a joins table between groups and forem_forums (called forum_groups) and define it as an association in your Group model like this:

has_many :forum_groups
has_many :forums, :through => :forum_groups, :class_name => "Forem::Forum"

You would need to also define a new model inside your application for this forum_groups association, it would be called ForumGroup and go a little like this:

class ForumGroup < ActiveRecord::Base
  belongs_to :forum, :class_name => "Forem::Forum"
  belongs_to :group
end

We’re doing it this way so you have an easy way to manage the associations between forums and groups. If you did has_and_belongs_to_many, it generally only provides a gigantic pain in the ass when you want to delete one specific record from that join table.

Now, with that all nicely set up, the method you want to define in your User model is this one:

def can_read_forem_forum?(forum)
  groups.joins(:forums).where("forem_forums.id = ?", forum.id).any?
end

Same thing, except this time we find all the groups that are linked to a specific forum through that association we set up earlier. This will do an INNER JOIN on the forum_groups table, and then another on the forem_forums table, getting the data required.

I hope this helps you, and thanks for using Forem!