Make find(projection=...) return copies of the values #753
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## develop #753 +/- ##
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+ Coverage 95.08% 95.14% +0.06%
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Files 19 19
Lines 3743 3731 -12
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- Hits 3559 3550 -9
+ Misses 184 181 -3
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I'm not sure if this needs a test to compare it against the real MongoDB engine or not. But I'll add one if you would like it. |
pcorpet
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Thanks for the PR. I don't think we need a test in test__mongomock for this one, so let's keep it like this.
mongomock/collection.py
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| else: | ||
| doc_copy = _project_by_spec( | ||
| doc, _combine_projection_spec(fields), | ||
| self._copy_field(doc, container), |
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This does the job but in many cases some values will be copied several times. I suggest that you update the _combine_projection_spec instead and add a copy in the places where the are no copies yet (doc_copy[key] = doc[key] and doc_copy[key] = val)
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Ah… I think I see what you mean – if fields are excluded (e.g.find_one(projection={'field': 0})) or nested fields are used (e.g. find_one(projection={'field.subfield': 1})), then _project_by_spec would copy the values a second time.
I'll update the pull request accordingly, but I'm wondering a bit about the container parameter. As far as I can tell it's never anything but dict, so I'm wondering what its purpose is and if it would be OK to just copy.deepcopy() the values?
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The container parameter was meant to use the implementation of the codec option document_class, if it's not too much trouble I'd like to keep it as such for now.
Make sure that the values returned from find() and find_one() when a projection is specified don't share any references to the actual db documents. Fixes mongomock#728
Copy only included fields, and only do it once.
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mongomock/collection.py
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| elif isinstance(val, dict): | ||
| doc_copy[key] = _project_by_spec(val, spec, is_include, container) | ||
| elif (is_include and spec is not NOTHING) or (not is_include and spec is NOTHING): | ||
| doc_copy[key] = copy.deepcopy(val) |
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Let's add at least a comment that this should use container if it's a dict-like object or may contain dict-like objects.
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I've changed it to use _copy_field instead now.
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Thanks or the change |
Make sure that the values returned from find() and find_one() when a
projection is specified don't share any references to the actual db
documents.
Fixes #728