Dealing with Scala types in Play templates

By default, Play Scala uses the same templating engine than Java. However the Scala plugin automatically enhances it to support natively some Scala specific features.

Boolean operations on Option and Seq types

You can safely use Option and Seq types in every boolean operations:

1. A None value is evaluated as false
2. A Some value is evaluated as true
3. An empty Seq is evaluated as false
4. A non empty Seq is evaluated as true

So you can for example safely use the ?: operator with an Option type:

Hello ${name ?: 'Guest'} 

Safe navigation for Option types

When you need to navigate more deeply into members contained in an Option type, you can use the ?. operator to automatically unwrap Some values and ignore None values.

For example, here the user variable reference an Option[User] type:

${user?.name?.toUpperCase()}

If the user variable contains a None value, no error will be thrown and an empty string will be displayed.

Also, when you display an Option value using an expression (like ${user}), the contained value is displayed, or an empty string if the value is None.

Litteral access to elements of a Seq

You can use the litteral way to access any value from of Scala Seq in a template:

def index = Template('items -> List(1,2,3))
 
---- index.html
 
<h1>${items[1]}</h1>