[SLING-3267] ResourceDecorator returning null should cause Resources to be ignored

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Won't Fix
• Affects Version/s: Resource Resolver 1.0.6
• Component/s: ResourceResolver
• Assignee: Bertrand Delacretaz
• Reporter: Bertrand Delacretaz
• Created: 06/Dec/13 10:40
• Updated: 10/Dec/13 10:30
• Resolved: 09/Dec/13 13:22

Description

The ResourceDecorator API's decorate(...) method javadocs currently specify that it can return null, but I don't think that's supported in a consistent way in the resource resolving process - returning null causes the resource resolver to supply a null Resource in some cases, which will probably cause NPEs downstream.

The javadocs also say "If the service does not want to decorate the resource, it should return the original resource" which is consistent with how the resource resolver currently operates: returning null is clearly not a way of saying "do not decorate this resource".

As we're discussing feature flags in Sling, we could clarify this behavior by specifying that a ResourceDecorator returning null causes the resource to be considered as non-existent, and making the corresponding (rather small) changes in the resource resolver code.

As every Resource needs to go through the available ResourceDecorators, this is a simple way of making resources hideable based on feature flags. One then just needs to implement a ResourceDecorator that returns null when a Resource must be ignored.

Issue Links

• is related to: SLING-3148 Implement support for Feature Flags/Toggles in Sling
• relates to: SLING-3269 ResourceDecorator returning null does not behave as specified