Rails Pundit unable to find policy of nil only on Create action after adding restrictions on some params

Question

I've modified one of my Goal.rb model to only allow one field to be edited by admins. This model and all actions within it was working prior to this update. This update also works for the edit action, but on the create action returns

Pundit::NotDefinedError in GoalsController#create unable to find policy of nil I'm hoping this is just a syntax error, I don't understand why it's not working as no model/policy file names have been changed, only the params and policy settings (which work for the edit action)

I thought it might be because I'm calling the policy on @goal while creating it, but how else would I check permissions there, if not this way?

goals_controller.rb:

def create
    @goal = Goal.new(permitted_attributes(@goal))
#stuff
    authorize @goal

    respond_to do |format|
      if @goal.save
#            format.json { render :show, status: :created, location: @goal }
      else
#            format.json { render json: @goal.errors, status: :unprocessable_entity }
      end
    end
  end

def update
    authorize @goal
    update_params = permitted_attributes(@goal)
  #
    end
    respond_to do |format|
      if @goal.update(update_params)
#            format.json { render :show, status: :ok, location: @goal }
      else
#            format.json { render json: @goal.errors, status: :unprocessable_entity }
      end
    end
  end

Answer 1

I just realised, you can call permissions on a new class. I had read this three times, but only after posting the question did it click.

I was trying to check the allowed params of @goal, which didn't yet exist and was showing a nil policy, but with Pundit you can run a check against the allowed params of a Class, in this case:

@goal = Goal.new(permitted_attributes(Goal))