Question

I get this error

undefined method `created_at’ for #ActiveRecord::Relation:0x0000001c3f57e8

controller

    @user = User.find_by_username(params[:username])
    @post = @user.comment_threads

    if @post
        last_time = @post.created_at
        if Time.now - last_time <= 0.5.minute
            redirect_to messages_received_path 
            flash[:notice] = "You cannot spam!"   
            return
        end
    end

Answer 1

Because this line @post = @user.comment_threads returns an object of ActiveRecord::Relation to you. Better put a .last or .first on the end of that sentence, so you can have a single Post object.