[TurboGears] Re: Adding transactions to @expose

[Jonathan LaCour]

What if my controller method calls another controller method that  
is also decorated to run inside a transaction?  Will the decorator  
be smart enough to use the current transaction?  In the case of a  
filter-based approach, you could instead start a transaction  
`onRequestStart`, rollback and display an error message  
`onRequestError`, and commit `onRequestEnd`.

Unfortunately, CherryPy filters will only allow us to rollback or  
commit. We can't actually display a meaningful page. I filed a  
ticket for this #392 with the CherryPy team, but they seem to think  
it is working correctly. I'll have to write a short example to show  
exactly what's going wrong.

This got me thinking that maybe filters are the wrong approach, as  
are decorators.  Why not make both the transaction-per-request and  
automated-error-handling WSGI middleware?  I am not an expert on the  
WSGI specification, but it seems at a cursory glance to be possible,  
and then we wouldn't have to convince CherryPy to change anything.

  -- Jonathan