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Nice work! The app now displays a list of all messages in the database. How does this work?

The file index.html.erb is a web template. Web templates are HTML files that contain variables and control flow statements. Rather than write the same HTML over and over again for each message, we can use web templates to loop through and display data from the database.

In this case:

<% @messages.each do |message| %> iterates through each message in @messages array. We created @messages in the Messages controller’s index action.
For each message, we use <%= message.content %> and <%= message.created_at %> to display its content and the time when it was created.

The default web templating language in Rails is embedded Ruby, or ERB.

Instructions

So far we’ve been loading messages from the database and displaying them in the view. How can we create new messages and save them to the database? Looking at the seven standard Rails actions, we need to use the new and create actions. Let’s set them up now.

In the routes file, create a route that maps requests to messages/new to the Message controller’s new action.

Then in the Messages controller below the index action, add the new action:

def new 
  @message = Message.new 
end

In the routes file, add this route to map requests to the Message controller’s create action:

post 'messages' => 'messages#create'

Then in the Messages controller below the new action, add a private method named message_params. Type:

private 
  def message_params 
    params.require(:message).permit(:content) 
  end

Between the new action and the private method, add the create action. Type:

def create 
  @message = Message.new(message_params) 
  if @message.save 
    redirect_to '/messages' 
  else 
    render 'new' 
  end 
end

Next, in app/views/messages/new.html.erb under line 11, type in the contents as you see here:

<%= form_for(@message) do |f| %>  
  <div class="field"> 
    <%= f.label :message %><br> 
    <%= f.text_area :content %> 
  </div> 
  <div class="actions"> 
    <%= f.submit "Create" %> 
  </div> 
<% end %>

Finally in app/views/messages/index.html.erb below the <% @messages.each do |message| %>...<% end %> block, add

<%= link_to 'New Message', "messages/new" %>

Visit http://localhost:8000/messages in the browser. Click on New Message to add a message of your own.

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