Add arg to understand, when we're in group

firestore/google/cloud/firestore_v1/client.py

@@ -257,7 +257,7 @@ def collection_group(self, collection_id):
             )
 
         collection = self.collection(collection_id)
-        return query.Query(collection, all_descendants=True)
+        return query.Query(collection, all_descendants=True, is_group=True)
 
     def document(self, *document_path):
         """Get a reference to a document in a collection.

firestore/google/cloud/firestore_v1/query.py

@@ -136,6 +136,7 @@ def __init__(
         start_at=None,
         end_at=None,
         all_descendants=False,
+        is_group=False,
     ):
         self._parent = parent
         self._projection = projection
@@ -146,6 +147,7 @@ def __init__(
         self._start_at = start_at
         self._end_at = end_at
         self._all_descendants = all_descendants
+        self._is_group = is_group
 
     def __eq__(self, other):
         if not isinstance(other, self.__class__):
@@ -214,6 +216,7 @@ def select(self, field_paths):
             start_at=self._start_at,
             end_at=self._end_at,
             all_descendants=self._all_descendants,
+            is_group=self._is_group,
         )
 
     def where(self, field_path, op_string, value):
@@ -283,6 +286,7 @@ def where(self, field_path, op_string, value):
             start_at=self._start_at,
             end_at=self._end_at,
             all_descendants=self._all_descendants,
+            is_group=self._is_group,
         )
 
     @staticmethod
@@ -335,6 +339,7 @@ def order_by(self, field_path, direction=ASCENDING):
             start_at=self._start_at,
             end_at=self._end_at,
             all_descendants=self._all_descendants,
+            is_group=self._is_group,
         )
 
     def limit(self, count):
@@ -361,6 +366,7 @@ def limit(self, count):
             start_at=self._start_at,
             end_at=self._end_at,
             all_descendants=self._all_descendants,
+            is_group=self._is_group,
         )
 
     def offset(self, num_to_skip):
@@ -388,6 +394,7 @@ def offset(self, num_to_skip):
             start_at=self._start_at,
             end_at=self._end_at,
             all_descendants=self._all_descendants,
+            is_group=self._is_group,
         )
 
     def _cursor_helper(self, document_fields, before, start):
@@ -419,9 +426,9 @@ def _cursor_helper(self, document_fields, before, start):
         if isinstance(document_fields, tuple):
             document_fields = list(document_fields)
         elif isinstance(document_fields, document.DocumentSnapshot):
-            if (
-                document_fields.reference._path[:-1] != self._parent._path
-                and document_fields.reference.parent._path[-1] != self._parent._path[0]
+            if document_fields.reference._path[:-1] != self._parent._path and not (
+                self._is_group
+                and document_fields.reference.parent._path[-1] == self._parent._path[0]
             ):
                 raise ValueError(
                     "Cannot use snapshot from another collection as a cursor."
@@ -438,6 +445,7 @@ def _cursor_helper(self, document_fields, before, start):
             "limit": self._limit,
             "offset": self._offset,
             "all_descendants": self._all_descendants,
+            "is_group": self._is_group,
         }
         if start:
             query_kwargs["start_at"] = cursor_pair

firestore/tests/unit/v1/test_collection.py

@@ -417,12 +417,10 @@ def test_start_after(self):
 
     def test_start_after_snapshot(self):
         from google.cloud.firestore_v1.query import Query
-        import types
 
         client = _make_client()
         parent_ref = self._make_one("parents", client=client).document("parent")
 
-        doc_fields = {"d": "foo"}
         child_col = parent_ref.collection("children")
         child_snapshot = child_col.document("child").get()