capturing python logging output to a string buffer

stringlog.py

import logging
from StringIO import StringIO

from five import grok

from xxx.objects.interfaces import IXXXResearcher
from Products.CMFCore.interfaces import ISiteRoot
from Products.statusmessages.interfaces import IStatusMessage

from xxx.objects.sync import sync_with_xxx

grok.templatedir("templates")

logger = logging.getLogger("XXX sync")
        

class SyncAll(grok.View):
    """
    Update all researcher data on the site from XXX (admin action)
    """

    grok.context(ISiteRoot)

    def sync(self):
        """ 
        Search all objects of certain type on the site and
        sync them with a remote site.
        """
       
        brains =  self.context.portal_catalog(object_provides=IXXXResearcher.__identifier__)
        for brain in brains:
            object = brain.getObject()
            sync_with_xxx(object, force=True)
            
    def startCapture(self, newLogLevel = None):
        """ Start capturing log output to a string buffer.

http://docs.python.org/release/2.6/library/logging.html

        @param newLogLevel: Optionally change the global logging level, e.g. logging.DEBUG
        """
        self.buffer = StringIO()
        
        print >> self.buffer, "Log output"
        
        rootLogger = logging.getLogger()
         
        if newLogLevel:
            self.oldLogLevel = rootLogger.getEffectiveLevel()
            rootLogger.setLevel(newLogLevel)
        else:
            self.oldLogLevel = None
            
        self.logHandler = logging.StreamHandler(self.buffer)
        formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
        self.logHandler.setFormatter(formatter)
        rootLogger.addHandler(self.logHandler)    
            
    def stopCapture(self):
        """ Stop capturing log output.
        
        @return: Collected log output as string        
        """
                                
        # Remove our handler
        rootLogger = logging.getLogger()        

        # Restore logging level (if any)
        if self.oldLogLevel:
            rootLogger.setLevel(self.oldLogLevel)

        
        rootLogger.removeHandler(self.logHandler)
        
        self.logHandler.flush()
        self.buffer.flush()
        
        return self.buffer.getvalue()
        
    def update(self):        
        """ Process the form.
        
        Process the form, log the output and show the output to the user.
        """
        
        self.logs = None

        if "sync-now" in self.request.form:
            # Form button was pressed
            
            # Open Plone status messages interface for this request
            messages = IStatusMessage(self.request)
             
            try:        
                self.startCapture(logging.DEBUG)
                
                logger.info("Starting full site synchronization")
                
                # Do the long running,
                # lots of logging stuff
                self.sync()    

                logger.info("Succesfully done")
                
                # It worked! Trolololo.
                messages.addStatusMessage("Sync done")
                
            except Exception, e:
                # Show friendly error message
                logger.exception(e)                
                messages.addStatusMessage(u"It did not work out:" + unicode(e)) 
   
            finally:
                # Put log output for the page template access
                self.logs = self.stopCapture()