fix overlap lookup in subqueries

fixes mongodb#209

Author: WaVEV

django_mongodb_backend/expressions.py

@@ -119,11 +119,10 @@ def query(self, compiler, connection, lookup_name=None):
  for col, i in subquery_compiler.column_indices.items()
  },
  }
+ wrapping_result_pipeline = None
  # The result must be a list of values. The output is compressed with an
  # aggregation pipeline.
  if lookup_name in ("in", "range"):
- if subquery.aggregation_pipeline is None:
- subquery.aggregation_pipeline = []
  wrapping_result_pipeline = [
  {
  "$facet": {
@@ -155,12 +154,49 @@ def query(self, compiler, connection, lookup_name=None):
  }
  },
  ]
+ if lookup_name == "overlap":
+ wrapping_result_pipeline = [
+ {
+ "$facet": {
+ "group": [
+ {"$project": {"tmp_name": expr.as_mql(subquery_compiler, connection)}},
+ {
+ "$unwind": "$tmp_name",
+ },
+ {
+ "$group": {
+ "_id": None,
+ "tmp_name": {"$addToSet": "$tmp_name"},
+ }
+ },
+ ]
+ }
+ },
+ {
+ "$project": {
+ field_name: {
+ "$ifNull": [
+ {
+ "$getField": {
+ "input": {"$arrayElemAt": ["$group", 0]},
+ "field": "tmp_name",
+ }
+ },
+ [],
+ ]
+ }
+ }
+ },
+ ]
+ if wrapping_result_pipeline:
  # If the subquery is a combinator, wrap the result at the end of the
  # combinator pipeline...
  if subquery.query.combinator:
  subquery.combinator_pipeline.extend(wrapping_result_pipeline)
  # ... otherwise put at the end of subquery's pipeline.
  else:
+ if subquery.aggregation_pipeline is None:
+ subquery.aggregation_pipeline = []
  subquery.aggregation_pipeline.extend(wrapping_result_pipeline)
  # Erase project_fields since the required value is projected above.
  subquery.project_fields = None

django_mongodb_backend/features.py

@@ -80,9 +80,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
  "auth_tests.test_views.LoginTest.test_login_session_without_hash_session_key",
  # GenericRelation.value_to_string() assumes integer pk.
  "contenttypes_tests.test_fields.GenericRelationTests.test_value_to_string",
- # overlap with values() returns no results:
- # https://github.com/mongodb-labs/django-mongodb/issues/209
- "model_fields_.test_arrayfield.QueryingTests.test_overlap_values",
  # icontains doesn't work on ArrayField:
  # Unsupported conversion from array to string in $convert
  "model_fields_.test_arrayfield.QueryingTests.test_icontains",