From 957cc0c2129cbba021a92a11b49048bb1543c862 Mon Sep 17 00:00:00 2001
From: Mauro Andre <eng.mauroandre@gmail.com>
Date: Tue, 14 Jan 2025 17:39:48 -0300
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20Fix=20group=20stage=20in=20pipel?=
 =?UTF-8?q?ine?=
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---
 pyodmongo/services/aggregate_stages.py   |  4 ++--
 pyodmongo/services/reference_pipeline.py | 14 +++++++-------
 requirements.txt                         |  4 ++--
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/pyodmongo/services/aggregate_stages.py b/pyodmongo/services/aggregate_stages.py
index ce5bbf2..3bdcd81 100644
--- a/pyodmongo/services/aggregate_stages.py
+++ b/pyodmongo/services/aggregate_stages.py
@@ -100,7 +100,7 @@ def set_(local_field: str, as_: str):
     return pipeline
 
 
-def group_set_replace_root(id_: str, array_index: str, field: str, path_str: str):
+def group_set_replace_root(id_: list[str], array_index: str, field: str, path_str: str):
     """
     Constructs a combination of group, set, and replaceRoot stages for a MongoDB aggregation pipeline.
 
@@ -120,7 +120,7 @@ def group_set_replace_root(id_: str, array_index: str, field: str, path_str: str
     return [
         {
             "$group": {
-                "_id": f"${id_}",
+                "_id": id_,
                 "_document": {"$first": "$$ROOT"},
                 field: {"$push": f"${path_str}"},
             }
diff --git a/pyodmongo/services/reference_pipeline.py b/pyodmongo/services/reference_pipeline.py
index 4d409ab..4158a1a 100644
--- a/pyodmongo/services/reference_pipeline.py
+++ b/pyodmongo/services/reference_pipeline.py
@@ -66,7 +66,7 @@ def resolve_reference_pipeline(
     )
     for db_field_path in paths:
         path_str = ""
-        unwind_index_list = []
+        unwind_index_list = ["_id"]
         paths_str_to_group = []
         db_field: DbField = None
         for index, db_field in enumerate(db_field_path):
@@ -99,16 +99,16 @@ def resolve_reference_pipeline(
             pipeline += set_(local_field=path_str, as_=path_str)
 
         for index, path_str in enumerate(reversed(paths_str_to_group)):
-            reverse_index = len(paths_str_to_group) - index - 1
-            unwind_index = (
-                "_id" if reverse_index - 1 < 0 else unwind_index_list[reverse_index - 1]
-            )
+            id_ = [
+                f"${e}" for e in unwind_index_list[: len(unwind_index_list) - index - 1]
+            ]
+            to_unset = unwind_index_list[-(index + 1)]
             pipeline += group_set_replace_root(
-                id_=unwind_index,
+                id_=[id_],
                 array_index=unwind_index_list[-1],
                 field=path_str.split(".")[-1],
                 path_str=path_str,
             )
-            pipeline += unset(fields=[unwind_index_list[reverse_index - 1]])
+            pipeline += unset(fields=[to_unset])
 
     return pipeline
diff --git a/requirements.txt b/requirements.txt
index 1a8311b..031b8e5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -47,8 +47,8 @@ pillow==10.3.0
 platformdirs==4.2.2
 pluggy==1.5.0
 pycparser==2.22
-pydantic==2.10.0
-pydantic_core==2.27.0
+pydantic==2.10.5
+pydantic_core==2.27.2
 Pygments==2.18.0
 pymdown-extensions==10.8.1
 pymongo==4.9.2