How to register a PolymerExpression filter inside a custom element, in Polymer.dart?

Question

How do I register a PolymerExpression filter inside a custom element? I am using Polymer.dart.

I want to use this:

<div>Uppercase: {{bob.fullName | uppercase}}</div>

inside the template of my custom element. Where do I register uppercase ?

Answer 1

Inside the PolymerElement, override instanceTemplate:

  DocumentFragment instanceTemplate(Element template) =>
      template.createInstance(this,
          new PolymerExpressions(globals: {
            'uppercase': (String input) => input.toUpperCase()
          }));

Notice you have to create an instance of PolymerExpressions and register the filter. Then you must call template.createInstance