fixing incompatibility with mongoengine aggregation to support mongo 4.4

Author: bagerard

mongoengine/mongodb_support.py

@@ -8,6 +8,7 @@
 # get_mongodb_version()
 MONGODB_34 = (3, 4)
 MONGODB_36 = (3, 6)
+MONGODB_44 = (4, 4)
 
 
 def get_mongodb_version():

mongoengine/queryset/base.py

@@ -1355,21 +1355,18 @@ def map_reduce(
 
         MapReduceDocument = _import_class("MapReduceDocument")
 
-        if not hasattr(self._collection, "map_reduce"):
-            raise NotImplementedError("Requires MongoDB >= 1.7.1")
-
         map_f_scope = {}
         if isinstance(map_f, Code):
             map_f_scope = map_f.scope
             map_f = str(map_f)
-        map_f = Code(queryset._sub_js_fields(map_f), map_f_scope)
+        map_f = Code(queryset._sub_js_fields(map_f), map_f_scope or None)
 
         reduce_f_scope = {}
         if isinstance(reduce_f, Code):
             reduce_f_scope = reduce_f.scope
             reduce_f = str(reduce_f)
         reduce_f_code = queryset._sub_js_fields(reduce_f)
-        reduce_f = Code(reduce_f_code, reduce_f_scope)
+        reduce_f = Code(reduce_f_code, reduce_f_scope or None)
 
         mr_args = {"query": queryset._query}
 
@@ -1379,7 +1376,7 @@ def map_reduce(
                 finalize_f_scope = finalize_f.scope
                 finalize_f = str(finalize_f)
             finalize_f_code = queryset._sub_js_fields(finalize_f)
-            finalize_f = Code(finalize_f_code, finalize_f_scope)
+            finalize_f = Code(finalize_f_code, finalize_f_scope or None)
             mr_args["finalize"] = finalize_f
 
         if scope:

tests/document/test_indexes.py

@@ -7,6 +7,7 @@
 
 from mongoengine import *
 from mongoengine.connection import get_db
+from mongoengine.mongodb_support import MONGODB_44, get_mongodb_version
 
 
 class TestIndexes(unittest.TestCase):
@@ -452,9 +453,11 @@ class Test(Document):
             .get("stage")
             == "IXSCAN"
         )
+        mongo_db = get_mongodb_version()
+        PROJECTION_STR = "PROJECTION" if mongo_db < MONGODB_44 else "PROJECTION_COVERED"
         assert (
             query_plan.get("queryPlanner").get("winningPlan").get("stage")
-            == "PROJECTION"
+            == PROJECTION_STR
         )
 
         query_plan = Test.objects(a=1).explain()

tests/queryset/test_queryset.py

@@ -21,7 +21,11 @@
     QuerySetManager,
     queryset_manager,
 )
-from tests.utils import requires_mongodb_gte_44
+from tests.utils import (
+    requires_mongodb_gte_44,
+    requires_mongodb_lt_42,
+    requires_mongodb_lte_42,
+)
 
 
 class db_ops_tracker(query_counter):
@@ -1490,6 +1494,7 @@ class BlogPost(Document):
 
         BlogPost.drop_collection()
 
+    @requires_mongodb_lt_42
     def test_exec_js_query(self):
         """Ensure that queries are properly formed for use in exec_js."""
 
@@ -1527,6 +1532,7 @@ class BlogPost(Document):
 
         BlogPost.drop_collection()
 
+    @requires_mongodb_lt_42
     def test_exec_js_field_sub(self):
         """Ensure that field substitutions occur properly in exec_js functions."""
 
@@ -3109,6 +3115,7 @@ class Person(Document):
         freq = Person.objects.item_frequencies("city", normalize=True, map_reduce=True)
         assert freq == {"CRB": 0.5, None: 0.5}
 
+    @requires_mongodb_lte_42
     def test_item_frequencies_with_null_embedded(self):
         class Data(EmbeddedDocument):
             name = StringField()
@@ -3137,6 +3144,7 @@ class Person(Document):
         ot = Person.objects.item_frequencies("extra.tag", map_reduce=True)
         assert ot == {None: 1.0, "friend": 1.0}
 
+    @requires_mongodb_lte_42
     def test_item_frequencies_with_0_values(self):
         class Test(Document):
             val = IntField()
@@ -3151,6 +3159,7 @@ class Test(Document):
         ot = Test.objects.item_frequencies("val", map_reduce=False)
         assert ot == {0: 1}
 
+    @requires_mongodb_lte_42
     def test_item_frequencies_with_False_values(self):
         class Test(Document):
             val = BooleanField()
@@ -3165,6 +3174,7 @@ class Test(Document):
         ot = Test.objects.item_frequencies("val", map_reduce=False)
         assert ot == {False: 1}
 
+    @requires_mongodb_lte_42
     def test_item_frequencies_normalize(self):
         class Test(Document):
             val = IntField()
@@ -3551,7 +3561,8 @@ class Book(Document):
         Book.objects.create(title="The Stories", authors=[mark_twain, john_tolkien])
 
         authors = Book.objects.distinct("authors")
-        assert authors == [mark_twain, john_tolkien]
+        authors_names = {author.name for author in authors}
+        assert authors_names == {mark_twain.name, john_tolkien.name}
 
     def test_distinct_ListField_EmbeddedDocumentField_EmbeddedDocumentField(self):
         class Continent(EmbeddedDocument):
@@ -3588,7 +3599,8 @@ class Book(Document):
         assert country_list == [scotland, tibet]
 
         continent_list = Book.objects.distinct("authors.country.continent")
-        assert continent_list == [europe, asia]
+        continent_list_names = {c.continent_name for c in continent_list}
+        assert continent_list_names == {europe.continent_name, asia.continent_name}
 
     def test_distinct_ListField_ReferenceField(self):
         class Bar(Document):

tests/utils.py

@@ -34,6 +34,14 @@ def get_as_pymongo(doc):
     return doc.__class__.objects.as_pymongo().get(id=doc.id)
 
 
+def requires_mongodb_lt_42(func):
+    return _decorated_with_ver_requirement(func, (4, 2), oper=operator.lt)
+
+
+def requires_mongodb_lte_42(func):
+    return _decorated_with_ver_requirement(func, (4, 2), oper=operator.le)
+
+
 def requires_mongodb_gte_44(func):
     return _decorated_with_ver_requirement(func, (4, 4), oper=operator.ge)