Flash
Flash support, allowing you to store information across requests and expire it immediately after a redirect, is included within Scalatra by default.
Basic usage
Flash entries are not normally available within the current request scope.
The exception is adding new flash entries into flash.now
.
In order to enable flash support, you’ll need to extend your servlet class
with FlashMapSupport
. You can set the flash like this:
class FooServlet extends ScalatraServlet with FlashMapSupport {
post("/articles/create") {
// watch out: this creates a session!
flash("notice") = "article created succesfully"
redirect("/home")
}
get("/home") {
ssp("/home")
}
}
and then you can use it in your view, to let the user know what happened.
home.ssp
might look like this:
<%@ import val flash:org.scalatra.FlashMap %>
<html>
<body>
<p>Here is the flash: <%= flash.get("notice") %></p>
</body>
</html>
Adding multiple entries
You can add more than one entry to the FlashMap
, using +=
:
flash = ("notice" -> "Hello from your application")
flash += ("error" -> "An error occurred")
flash.now += ("info" -> "redirect to see the error")
flash.now
operates pretty much in the same way as flash
does, except that
it sets a value for the current request only. It will be removed before the
next request unless explicitly kept.
FlashMapSupport and sessions
Please note: extending your ScalatraServlet
with FlashMapSupport
triggers
a session, which is why it’s an optional mixin.