converting the methods for a has_many association to a has_one association

Question

I have 2 models, users, and common_apps.

users has_one :common_app.

Before this, I wrote the code as the users has_many common_apps, however I'm not sure how to rewrite that for a has_one association. The main confusion is how to structure 'new' in common_app controller.

When I try, I get an undefined method error.

undefined method `new' for #<CommonApp:>

This is my code -->

def new
    if current_user.common_app.any?
      redirect_to current_user
    else
        @common_app = current_user.common_app.new 
    end
  end

  def create 
    @common_app = current_user.common_app.build(common_app_params)
    if @common_app.save
        flash[:success] = "Common App Created!"
        redirect_to root_url
    else
        redirect_to 'common_apps/new'
    end
  end

  def show
    @common_apps = current_user.common_app
  end

how would you restructure this, if this were to be a has_one association?

I think I know how the 'create' one should be -->

      def create 
        @common_app = current_user.build_common_app(common_app_params)
        if @common_app.save
            flash[:success] = "Common App Created!"
            redirect_to root_url
        else
            redirect_to 'common_apps/new'
        end
      end

Answer 1

Your new action should look like this:

def new
  if current_user.common_app.present?
    redirect_to current_user
  else
    @common_app = current_user.build_common_app
  end
end

You can also call build_common_app without any parameters passed to it, which will initialize an empty CommonApp for current_user .