About the Upload linker category

Upload linker: Links any AbstractComponent to an Upload component. This means that upon a click on the linked component this click will be “forwarded” to the uploader and trigger its file selector window. Multiple uploaders can be successively linked to a single upload; multiple components can also be linked to a single uploader. Simply call link(AbstractComponent, Upload) for each component/uploader combination.

Known limitations:

  • The linking is not permanent. If you reload a page you must reapply it.
  • Both the component and the uploader must be added towards the view where you want to use them.
  • Both the component and the uploader must be visible (i.e., don’t use Component#setVisible(boolean) with false as this removes the component from the DOM.
  • After the linking the upload component will be made invisible via CSS (style.display=‘none’). This may affect your layout! So best add the uploader at a convenient space - for instance at the bottom
  • The component and the uploader must have their IDs set. See: Upload#setId(String),
    AbstractComponent#setId(String)
  • These IDs must be unique.
  • In case you build your UI lazily ensure that the components you want to link are present. This method waits an increasing amount of time (25ms, 50ms, 75ms, …)
  • for the components to be found and will time out after about 12s (30 attempts). (You can check successful/failed linkings via your browser’s console.)
  • Other registered ClickListeners will still fire for the source and target component.