Sinatra Views

Overview

We'll explore the purpose of views in a Sinatra application and will render them as separate files.

Objectives

Explain the advantage of storing HTML in a separate file from app.rb
Create index.erb in the views directory
Update your controller to render appropriate erb files
Render multiple routes with multiple views

Part 1: Rendering HTML

Rendering plain text is a great way to test the behaviors of our routes, but it doesn't give us any control over how the content is displayed. We'd like to structure our content using HTML and render that to the browser instead. The most basic way to do this is to include html tags as a part of the string we're rendering. If you haven't already, fork, clone, and open this lab. In the "/" route of our app.rb file, try the following:

get '/' do
	"<h1>Hello World</h1>"
end

Run shotgun and go to http://localhost:9393 or the IP Address:PORT provided by the Learn IDE. Your "Hello World" text should now appear as an <h1>. Nice!

Part 2: Using an ERB File

You can imagine that writing HTML this way would get very messy, very quickly. Luckily, most web frameworks include a templating engine that allows us to render HTML content from a different file. We call these files "views." Views represent what the user sees and comprise the "V" in "MVC."

By default, Sinatra uses a templating engine called ERB, or Embedded RuBy. Our view files will use the extension .erb and we can write HTML code there just like in a plain old .html file. Sinatra is also configured by default to look for our .erb files in a directory called views.

Create a new file called index.erb inside of the views directory. Add the following code into that file.

<!DOCTYPE html>
<html>
	<head>
		<title>My First View!!</title>
	</head>
	<body>
		<h1>Hello World</h1>
		<p>This HTML code is inside of a '.erb' file in the views directory, where it belongs.</p>
	</body>
</html>

Now, we just need to update our controller to render the index.erb file at the "/" route. The syntax for this is as follows:

	get '/' do
	  erb :index
	end

This tells Sinatra to render a file called index.erb inside of a directory called views. Save your files and refresh your preview to see your changes. Awesome, right?

Part 3: Multiple Routes with Multiple Views

We can create as many routes and views as we want. Let's create a route called "/info" in our controller.

	get '/' do
	  erb :index
	end
	
	get "/info" do
	  "Testing the info page"
	end

Run shotgun and go to http://localhost:9393 or the IP Address:PORT provided by the Learn IDE. Your "Hello World" text should now appear as an <h1>. Nice! With shotgun running, head to http://localhost:9393/info . You should see "Testing the info page" rendered there. This lets us know that our route is defined properly. Next, let's have this route render a separate file instead. Inside of the views directory, create a file called info.erb. Add whatever HTML code you like.

<!DOCTYPE html>
<html>
	<head>
		<title>Info Page</title>
	</head>
	<body>
		<h1>Info Page</h1>
		<p>This is the info page: here's some information about me!</p>
	</body>
</html>

Finally, update our controller to render that file.

	get '/' do
	  erb :index
	end
	
	get "/info" do
	  erb :info
	end

It's important to note that the name of the file doesn't have to match the name of the route. For example, if we wanted our "/info" route to render a file called dogs.erb, we could do so like this:

	get '/' do
	  erb :index
	end
	
	get "/info" do
	  erb :dogs
	end

By convention though, we keep our routes and our erb files named the same. This makes it easier to keep track of as our projects get bigger.