Rendering templates

So far, our application does not actually return HTML, it returns just plain text.

Let’s fix that.

For this we’ll want to re-use what we’ve learned about rendering ERB templates. In order to use ERB we need to require it, define an ERB template, and make any variables used in the template known as local variables in our route:

require "sinatra"
require "erb"

get '/monstas/:name' do"<h1>Hello <%= params[:name] %></h1>").result(binding)

This code is familiar to you, isn’t it?

We get use params[:name] in the template because params is “known” in the scope that is passed as part of the binding. The rest is just the same as in our examples in the chapters about ERB

If you restart the server, and reload the page in your browser, it should now look like this:

Awesome, we’re now serving HTML, not just plain text.

However, Sinatra also has built-in support for ERB templates (“views”). We can achieve exactly the same thing without spelling out the noise:

get '/monstas/:name' do
  erb "<h1>Hello <%= name %></h1>", { :locals => { :name => params[:name] } }

I.e. Sinatra has a method erb that hides all the details of rendering the template from us, and also accepts a template.

On top of this, it also accepts a hash that allows us to specify various options. If we specify a key :locals and give it another hash, then Sinatra will make each key/value pair on this hash available as local variables (thus “locals”) in our ERB template.

Of course, since params already is a hash, and it already has the key name defined, we can also just say:

get '/monstas/:name' do
  erb "<h1>Hello <%= name %></h1>", { :locals => params }

Nice, isn’t it.