Uploaded image for project: 'Sling'
  1. Sling
  2. SLING-6559

Sling is hiding / ignoring Parameter / Query String changes from Filters ahead of Sling



    • Bug
    • Status: Resolved
    • Major
    • Resolution: Won't Fix
    • None
    • None
    • Engine
    • Sling 9, JDK 1.8


      Any changes to parameters or the query string in a Servlet Filter ahead of Sling (before Sling Main Servlet) are ignore in Sling due to the usage of the Parameter Support class.

      This means that any such filter will not receive the parameters in the request, cannot wrap the request and add, change or delete them and cannot change the query string.

      I attached a sample project that will showcase that (see the ReadMe.markdown) file in the root folder. The project can be built with *mvn clean install* and if Composum is installed and whitelisted you can auto deploy it with (mvn clean install -P auto-deploy-all.

      I know this is an edge case but I had at least two clients in the last two years
      that required to change parmaeters and / or query strings before the Sling resource
      is resolved.

      But even without that Sling based on javax.servlet specification should adhere to
      that and with it support and respect filters and their changes.

      The reason why this goes wrong is that the Parameter Support is created during the
      authentication phase way ahead of "regular" filters and with it the parameters
      are fixed into place.

      For a client I created a fixe by intercepting the getAttribute() for the Parameter
      Support attribute and return null to create a new Parameter Support instance. To
      make this work I had to read out all parameters from the original Parameter Support
      instance to carry them over as well as set the flag for additional parameters.
      This is working in AEM 6.2 SP1 but this is for sure not a good and generic solution.




            Unassigned Unassigned
            andysch Andreas Schaefer
            0 Vote for this issue
            1 Start watching this issue