+def create_pub_filepath(entry, filename):
+ return mgg.public_store.get_unique_filepath(
+ ['media_entries',
+ unicode(entry['_id']),
+ filename])
+
+
+################################
+# Media processing initial steps
+################################
+
+class ProcessMedia(Task):
+ """
+ Pass this entry off for processing.
+ """
+ def run(self, media_id):
+ """
+ Pass the media entry off to the appropriate processing function
+ (for now just process_image...)
+ """
+ entry = mgg.database.MediaEntry.one(
+ {'_id': ObjectId(media_id)})
+
+ # Try to process, and handle expected errors.
+ try:
+ process_image(entry)
+ except BaseProcessingFail, exc:
+ mark_entry_failed(entry[u'_id'], exc)
+ return
+
+ entry['state'] = u'processed'
+ entry.save()
+
+ def on_failure(self, exc, task_id, args, kwargs, einfo):
+ """
+ If the processing failed we should mark that in the database.
+
+ Assuming that the exception raised is a subclass of BaseProcessingFail,
+ we can use that to get more information about the failure and store that
+ for conveying information to users about the failure, etc.
+ """
+ entry_id = args[0]
+ mark_entry_failed(entry_id, exc)
+
+
+process_media = registry.tasks[ProcessMedia.name]
+
+
+def mark_entry_failed(entry_id, exc):
+ """
+ Mark a media entry as having failed in its conversion.
+
+ Uses the exception that was raised to mark more information. If the
+ exception is a derivative of BaseProcessingFail then we can store extra
+ information that can be useful for users telling them why their media failed
+ to process.
+
+ Args:
+ - entry_id: The id of the media entry
+
+ """
+ # Was this a BaseProcessingFail? In other words, was this a
+ # type of error that we know how to handle?
+ if isinstance(exc, BaseProcessingFail):
+ # Looks like yes, so record information about that failure and any
+ # metadata the user might have supplied.
+ mgg.database['media_entries'].update(
+ {'_id': entry_id},
+ {'$set': {u'state': u'failed',
+ u'fail_error': exc.exception_path,
+ u'fail_metadata': exc.metadata}})
+ else:
+ # Looks like no, so just mark it as failed and don't record a
+ # failure_error (we'll assume it wasn't handled) and don't record
+ # metadata (in fact overwrite it if somehow it had previous info
+ # here)
+ mgg.database['media_entries'].update(
+ {'_id': entry_id},
+ {'$set': {u'state': u'failed',
+ u'fail_error': None,
+ u'fail_metadata': {}}})
+
+
+def process_image(entry):
+ """
+ Code to process an image
+ """
+ workbench = mgg.workbench_manager.create_workbench()