How to add a property to a map dynamically in velocity?

Question

I have the following code

$pageName = "test";

$Container = {};

I like to set a property of $Container by a variable. I tried $Container.set("test", $pageName);. It didn't raise any errors, but $Container.test or $Container.get("test"); display nothing.

How do I fix it?

Answer 1

The problem is that set is the wrong method. You need to do a put. Remember - Velocity is calling the Java methods. There is no "set" method on a Map object.

Specifically, you can do

$Container.put("test", $pageName)

Now, one weird thing is that this will print "true" or "false" in the page, since the Map.put() method returns a boolean. So I always do

#set($dummy = $Container.put("test", $pageName))

which does the put and stores the result in another reference (which you can then ignore) instead of rendering it to the page.