Updated recent bugfix with embedded DOc deepcopy so that it set _instance to None

docs/changelog.rst

@@ -8,6 +8,7 @@ Development
 ===========
 - (Fill this out as you fix issues and develop your features).
 - EnumField improvements: now `choices` limits the values of an enum to allow
+- Missing `._instance` field after deepcopy of EmbeddedField (#2202
 
 Changes in 0.23.1
 ===========

mongoengine/document.py

@@ -101,7 +101,7 @@ class EmbeddedDocument(BaseDocument, metaclass=DocumentMetaclass):
 
     def __getstate__(self):
         data = super().__getstate__()
-        data["_instance"] = self._instance
+        data["_instance"] = None
         return data
 
     def __setstate__(self, state):
@@ -135,7 +135,7 @@ class Document(BaseDocument, metaclass=TopLevelDocumentMetaclass):
     create a specialised version of the document that will be stored in the
     same collection. To facilitate this behaviour a `_cls`
     field is added to documents (hidden though the MongoEngine interface).
-    To enable this behaviourset :attr:`allow_inheritance` to ``True`` in the
+    To enable this behaviour set :attr:`allow_inheritance` to ``True`` in the
     :attr:`meta` dictionary.
 
     A :class:`~mongoengine.Document` may use a **Capped Collection** by

tests/document/test_instance.py

@@ -3,7 +3,6 @@ import pickle
 import unittest
 import uuid
 import weakref
-from copy import deepcopy
 from datetime import datetime
 
 import bson
@@ -79,14 +78,6 @@ class TestDocumentInstance(MongoDBTestCase):
         else:
             assert field._instance == instance
 
-    def test_deepcopy(self):
-        """Ensure that the _instance attribute on EmbeddedDocument exists after a deepcopy"""
-
-        doc = self.Job()
-        assert doc._instance is None
-        copied = deepcopy(doc)
-        assert copied._instance is None
-
     def test_capped_collection(self):
         """Ensure that capped collections work properly."""
 

tests/fields/test_embedded_document_field.py

@@ -1,4 +1,7 @@
+from copy import deepcopy
+
 import pytest
+from bson import ObjectId
 
 from mongoengine import (
     Document,
@@ -9,6 +12,7 @@ from mongoengine import (
     InvalidQueryError,
     ListField,
     LookUpError,
+    MapField,
     StringField,
     ValidationError,
 )
@@ -350,3 +354,30 @@ class TestGenericEmbeddedDocumentField(MongoDBTestCase):
         # Test existing attribute
         assert Person.objects(settings__base_foo="basefoo").first().id == p.id
         assert Person.objects(settings__sub_foo="subfoo").first().id == p.id
+
+    def test_deepcopy_set__instance(self):
+        """Ensure that the _instance attribute on EmbeddedDocument exists after a deepcopy"""
+
+        class Wallet(EmbeddedDocument):
+            money = IntField()
+
+        class Person(Document):
+            wallet = EmbeddedDocumentField(Wallet)
+            wallet_map = MapField(EmbeddedDocumentField(Wallet))
+
+        # Test on fresh EmbeddedDoc
+        emb_doc = Wallet(money=1)
+        assert emb_doc._instance is None
+        copied_emb_doc = deepcopy(emb_doc)
+        assert copied_emb_doc._instance is None
+
+        # Test on attached EmbeddedDoc
+        doc = Person(
+            id=ObjectId(), wallet=Wallet(money=2), wallet_map={"test": Wallet(money=2)}
+        )
+        assert doc.wallet._instance == doc
+        copied_emb_doc = deepcopy(doc.wallet)
+        assert copied_emb_doc._instance == doc
+
+        copied_map_emb_doc = deepcopy(doc.wallet_map)
+        assert copied_map_emb_doc["test"]._instance == doc