Learning Rails

Adding Logic to the View

You can also put more sophisticated logic into the views, thanks to the <% and %> tags. (The opening tag lacks the = sign.) These tags let you put Ruby code directly into your ERb files. We’ll start with a very simple example, shown in Example 2-9, that takes advantage of the count variable in the controller. (This example is part of the ch02/hello003 code sample.)

Example 2-9. Modifying index.html.erb to present the @bonus message as many times as @count specifies

<html>
<head><title><%=h @message %> </title></head>
<body>
<h1><%=h @message %></h1>
<p>This is a greeting from app/views/hello/index.html.erb</p>

<% for i in 1..@count %>
  <p><%=h @bonus %></p>
<% end %>

</body>
</html>

The count variable now controls the number of times the bonus message appears because of the for...end loop, which will simply count from 1 to the value of the count variable.

Note

The for loop is familiar to developers from a wide variety of programming languages, but it’s not especially idiomatic Ruby. Ruby developers would likely use a times construct instead, such as:

<% @count.times do %>
<p><%=h @bonus %></p>
<% end %>

Depending on your fondness for punctuation, you can also replace the do and end with curly braces, as in:

<% @count.times {  %>
<p><%=h @bonus %></p>
<% } %>

As always, you can choose the approach you find most comfortable.

The loop will run three times, counting up to the value the controller set for the count variable. As a result, “This message came from the controller.” ...