Question

I have Discussions (polymorphic) that belong to Projects, Tasks and Subtasks. Tasks belong to Projects, and Subtasks to Tasks.

I have users connected to Projects via join table called ‘synapses’. Synapse model has user_id, project_id and boolean field called :leader which signals if the user has leader (AKA admin) rights.

For a user to close(finish) the discussion, he needs to be a leader of current project or needs to be the creator of that discussion. Here is the ‘finish’ method in Discussions controller:

 33   def finish
 34     if current_user.leader? || current_user.discussions.include?(@discussion)
 35       @discussion.update_attribute(:finished, true)
 36       redirect_to polymorphic_path([@parent, Discussion])
 37       flash[:notice] = "Discussion '#{@discussion.name}' finished"
 38     else
 39       flash[:alert] = 'You must be an admin to do that'
 40     end
 41   end

Since user model doesn’t have leader attribute on itself, I need to find the corresponding synapse between current user and project(which does have leader boolean field, showing if the user can close the discussion). Here is the method I have in application_controller to find the synapse:

  9   def find_synapse(user,project)  
 10     user.synapses.find_by_project_id(project)
 11   end

To find the synapse, I need to find the Project. So far I can find the parent of the Discussion, which can be either the Project, Task, or Subtask model.

The way I see it, I need to iterate through parents and than stop when the parent’s is of the class Project (for loop?). How to do this? Is this the best way to go about it? BTW, I tried using switch-case (when @parent.class is Task, do this, when class is Project, do that), but seems hackish and I didn’t manage it to work anyway.

Answer 1

If you define a method owning_product on project, task, subtask such that

class Project
  def owning_project
    self
  end
end

class Task
  def owning_project
    project
  end
end

class Subtask
  def owning_project
    task.owning_project
  end
end

Then you can call owning_project on your discussion’s parent and get back the relevant project. In a way this is pretty much the same as your case statement but using the inheritance system to do the switching for you.