Detecting Mappings in Components

Use Lit templates instead
Lit templates are recommended. Polymer templates are available in the next long term supported Vaadin version (LTS), but they are deprecated.

You can detect whether a component is part of a Polymer template using the isTemplateMapped method.

This is useful if you want to execute custom logic depending on whether the component was mapped in a template (injected via the @Id or @Uses annotations) or created directly using one of its constructors, for example.

Example: Calling the isTemplateMapped method in MyComponent.

public class MyComponent extends Div {

  public MyComponent() {
    if (!isTemplateMapped()) {
      getElement().getStyle().set("color", "red");
  • By default, the component only sets a style when the component is not part of a template.

See Binding Components from a PolymerTemplate for more about To @Id mappings.