POC add expression support to QuerySet.update() #111
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django_mongodb/compiler.py
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| if is_empty: | ||
| rows = 0 | ||
| else: | ||
| base_pipeline = [ |
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This part is the only thing that need focus. Here I just create the $merge pipeline and the affected rows pipeline with a single transaction. I really don't know if this is the way to go.
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This is the right way to go about it. having a transaction ensures that state isn't changed between the lookup and the update.
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I think we can use update many directly as Shane mentioned. I've re-read the docs and what the docs support are this three stages.
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Yeap, It works 🚀. So we are able to do the update without making two queries (one for count and the other for the update)
django_mongodb/compiler.py
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| if is_empty: | ||
| rows = 0 | ||
| else: | ||
| base_pipeline = [ |
There was a problem hiding this comment.
This is the right way to go about it. having a transaction ensures that state isn't changed between the lookup and the update.
django_mongodb/compiler.py
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| ] | ||
| with self.connection.connection.start_session() as session, session.start_transaction(): | ||
| result = next(self.collection.aggregate(count_pipeline), {"count": 0}) | ||
| self.collection.aggregate(pipeline) |
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what has been the output when you merge:
[*base_pipeline, {$merge..}, {$count...}] Does this not work whatsoever?
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The final implementation is in #112 |
timgraham
changed the title
This is a quick approach to support expression in updates. I have to say that the update pipeline is not expressive as it's needed