Understanding Rails Flash Messages

April 2024 — by Ahmed Abd El-Latif

Flash messages in Rails are a simple way to give feedback to users after actions like creating, updating, or deleting records. They are easy to use and make your app feel more interactive and user-friendly.

How to Use Flash Messages

In your controller, you can set a flash message like this:

1def create
2  @post = Post.new(post_params)
3  if @post.save
4    flash[:notice] = "Post was successfully created!"
5    redirect_to @post
6  else
7    flash[:alert] = "There was an error creating the post."
8    render :new
9  end
10end

And in your layout (e.g., application.html.erb):

1<% flash.each do |key, message| %>
2  <div class="flash <%= key %>"><%= message %></div>
3<% end %>

That's it! Now your users will see helpful messages after their actions.