FileFeedStorage creates empty file when no items are scraped

[gbirke]

When no items are scraped, the corresponding file is created none the less, because it is created in by the storage.open call in FeedExporter.open_spider. This behavior ignores the the setting of FEED_STORE_EMPTY when using file export.

My proposal for this would be to add a cleanup method to the IFeedStorage interface. Then FeedExporter.close_spider can call that method before returning in case slot.itemcount is zero and self.store_empty is False. cleanup could also be called internally from the store methods of the IFeedStorage implementations.

[michael-yin]

@gbirke I have met the same problem, there are so many empty files when you save data to files, and your proposal sounds like a good idea to me. IFeedStorage need to be added a new method called in close_spider of FeedExporter

[dfockler]

I'm having a similar issue, where the JSONItemExporter will write out the opening [ when calling it's start_exporting method but if there are no items scraped, it's finish_exporting method never gets called, and the closing ] is never added, so any resources consuming that JSON file will throw errors because of the invalid JSON format.