Allow setting default_handler as a session preference

[Ryan J Ollos]

The proposed feature will make it possible to set the default_handler from the Preferences page or using a TracAdmin command (trac-admin session set). The feature was previously mentioned in comment:17:ticket:11519.

Together with an enhancement to be proposed to the ​th:AccountManagerPlugin, this will support convenient configuration of a use-case for which I've previously used the ​th:GroupBasedRedirectionPlugin - having members of groups/teams arrive at different pages when logging in to Trac.

[Ryan J Ollos]

The core functionality has been implemented in log:rjollos.git:t11597. However, I'll add tests before committing.

[Jun Omae]

I don't think the selected handler is always valid for default handler. I think we should check whether the handler is valid.

trac/web/main.py

@@ -276 +276 @@
         # Use default_handler from the Session if it is a valid value.
         name = req.session.get('default_handler')
         handler = self._request_handlers.get(name)
+        if handler and not is_valid_default_handler(handler):
+            handler = None
 
         if not handler:
             # Use default_handler from project configuration.

[Ryan J Ollos]

Good catch. I will include it and make sure we have test coverage.

[Ryan J Ollos]

log:rjollos.git:t11597.2 contains some refactoring of the proposed changes. Functional tests still need to be added.

[Ryan J Ollos]

Proposed changes in log:rjollos.git:t11597.3, with functional and unit tests.

[Ryan J Ollos]

Committed to trunk in [12922].