Accessing Form Data

We mentioned earlier that form data will be available in the params hash.

Let’s check that by outputting the params in our route:

get "/monstas" do
  p params
  erb :monstas

Again, restart the application, and load the URL http://localhost:4567/monstas?name=Monstas. In your terminal you should then see something like:


So this is how we can access the data that has been passed from the browser as part of the HTTP request, when it submitted the form.

Let’s do something with it!

Change your route like so:

get "/monstas" do
  @name = params["name"]
  erb :monstas

And add this code at the top of your monstas.erb view:

<% if @name %>
  <h1>Hello <%= @name %>!</h1>
<% end %>

When you restart the server, and reload the page you should see something like this:


So this is how you can pass (submit) data from the brower to your application, and use it in some way.

Let’s make one more improvement to our form. It currently always wipes out the text that has been submitted. Let’s make sure we preseve it in the input element.

We can do that by specifying the value attribute on the input tag, like so:

<form action="/monstas">
  <input type="text" name="name" value="<%= @name %>">
  <input type="submit">

When you restart your application, and reload the page, it should now put the name to the input element: