JSF 2.0: Preserving component state across multiple views
- by tlind
The web application I am developing using MyFaces 2.0.3 / PrimeFaces 2.2RC2 is divided into a content and a navigation area. In the navigation area, which is included into multiple pages using templating (i.e. <ui:define>), there are some widgets (e.g. a navigation tree, collapsible panels etc.) of which I want to preserve the component state across views.
For example, let's say I am on the home page. When I navigate to a product details page by clicking on a product in the navigation tree, my Java code triggers a redirect using
navigationHandler.handleNavigation(context, null,
"/detailspage.jsf?faces-redirect=true")
Another way of getting to that details page would be by directly clicking on a product teaser that is shown on the home page. The corresponding <h:link> would lead us to the details page.
In both cases, the expansion state of my navigation tree (a PrimeFaces tree component) and my collapsible panels is lost. I understand this is because the redirect / h:link results in the creation of a new view.
What is the best way of dealing with this? I am already using MyFaces Orchestra in my project along with its conversation scope, but I am not sure if this is of any help here (since I'd have to bind the expansion/collapsed state of the widgets to a backing bean... but as far as I know, this is not possible). Is there a way of telling JSF which component states to propagate to the next view, assuming that the same component exists in that view?
I guess I could need a pointer into the right direction here. Thanks!
Update 1: I just tried binding the panels and the tree to a session-scoped bean, but this seems to have no effect. Also, I guess I would have to bind all child components (if any) manually, so this doesn't seem like the way to go.
Update 2: Binding UI components to non-request scoped beans is not a good idea (see link I posted in a comment below). If there is no easier approach, I might have to proceed as follows:
When a panel is collapsed or the tree is expanded, save the current state in a session-scoped backing bean (!= the UI component itself)
The components' states are stored in a map. The map key is the component's (hopefully) unique, relative ID. I cannot use the whole absolute component path here, since the IDs of the parent naming containers might change if the view changes, assuming these IDs are generated programmatically.
As soon as a new view gets constructed, retrieve the components' states from the map and apply them to the components. For example, in case of the panels, I can set the collapsed attribute to a value retrieved from my session-scoped backing bean.
