tweets_controller.rb

class TweetsController < ApplicationController
  def new
    @tweet = Tweet.new
  end

  def create
    @tweet = current_user.tweets.build(params[:tweet])

    if @tweet.save
      @tweet.deliver!
      redirect_to new_tweet_path, :notice => t(:scheduled_tweet)
    else
      flash[:error] = @tweet.errors.full_messages.first
      render :new
    end
  end

  private

  def tweet_params
    params.require(:body, :post_at)
  end
end

# Error: 
# ActiveModel::ForbiddenAttributesError: ActiveModel::ForbiddenAttributesError
#     app/controllers/tweets_controller.rb:7:in `create'