From af400e5c832aaace334c845073c6c994222cefb6 Mon Sep 17 00:00:00 2001
From: maxi297 <maxime@airbyte.io>
Date: Tue, 25 Mar 2025 17:20:41 -0400
Subject: [PATCH 1/2] fix substreampartitionrouter state migration from child
 when it is empty

---
 .../substream_partition_router.py                  |  2 +-
 .../test_substream_partition_router.py             | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/airbyte_cdk/sources/declarative/partition_routers/substream_partition_router.py b/airbyte_cdk/sources/declarative/partition_routers/substream_partition_router.py
index 50fe4f0bc..59fda9396 100644
--- a/airbyte_cdk/sources/declarative/partition_routers/substream_partition_router.py
+++ b/airbyte_cdk/sources/declarative/partition_routers/substream_partition_router.py
@@ -374,7 +374,7 @@ def _migrate_child_state_to_parent_state(self, stream_state: StreamState) -> Str
         # Ignore per-partition states or invalid formats.
         if isinstance(substream_state, (list, dict)) or len(substream_state_values) != 1:
             # If a global state is present under the key "state", use its first value.
-            if "state" in stream_state and isinstance(stream_state["state"], dict):
+            if "state" in stream_state and isinstance(stream_state["state"], dict) and stream_state["state"] != {}:
                 substream_state = list(stream_state["state"].values())[0]
             else:
                 return {}
diff --git a/unit_tests/sources/declarative/partition_routers/test_substream_partition_router.py b/unit_tests/sources/declarative/partition_routers/test_substream_partition_router.py
index c4a608f4a..7df7023c2 100644
--- a/unit_tests/sources/declarative/partition_routers/test_substream_partition_router.py
+++ b/unit_tests/sources/declarative/partition_routers/test_substream_partition_router.py
@@ -473,6 +473,19 @@ def test_substream_partition_router_invalid_parent_record_type():
             },
             {"parent_stream_cursor": "2023-05-27T00:00:00Z"},
         ),
+        # Case 7: Migrate child state to parent state but child state is empty
+        (
+                {
+                    "state": {},
+                    "states": [],
+                    "parent_state": {
+                        "posts": {}
+                    },
+                    "lookback_window": 1,
+                    "use_global_cursor": False
+                },
+                {},
+        ),
     ],
     ids=[
         "empty_initial_state",
@@ -481,6 +494,7 @@ def test_substream_partition_router_invalid_parent_record_type():
         "initial_state_no_parent_per_partition_state",
         "initial_state_with_parent_state",
         "initial_state_no_parent_global_state_declarative",
+        "initial_state_no_parent_and_no_child",
     ],
 )
 def test_set_initial_state(initial_state, expected_parent_state):

From 26095cb5a676a8ea1fb11dfc7657bd20989a485c Mon Sep 17 00:00:00 2001
From: octavia-squidington-iii <contact@airbyte.com>
Date: Tue, 25 Mar 2025 21:39:02 +0000
Subject: [PATCH 2/2] Auto-fix lint and format issues

---
 .../substream_partition_router.py              |  6 +++++-
 .../test_substream_partition_router.py         | 18 ++++++++----------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/airbyte_cdk/sources/declarative/partition_routers/substream_partition_router.py b/airbyte_cdk/sources/declarative/partition_routers/substream_partition_router.py
index 59fda9396..000beeff9 100644
--- a/airbyte_cdk/sources/declarative/partition_routers/substream_partition_router.py
+++ b/airbyte_cdk/sources/declarative/partition_routers/substream_partition_router.py
@@ -374,7 +374,11 @@ def _migrate_child_state_to_parent_state(self, stream_state: StreamState) -> Str
         # Ignore per-partition states or invalid formats.
         if isinstance(substream_state, (list, dict)) or len(substream_state_values) != 1:
             # If a global state is present under the key "state", use its first value.
-            if "state" in stream_state and isinstance(stream_state["state"], dict) and stream_state["state"] != {}:
+            if (
+                "state" in stream_state
+                and isinstance(stream_state["state"], dict)
+                and stream_state["state"] != {}
+            ):
                 substream_state = list(stream_state["state"].values())[0]
             else:
                 return {}
diff --git a/unit_tests/sources/declarative/partition_routers/test_substream_partition_router.py b/unit_tests/sources/declarative/partition_routers/test_substream_partition_router.py
index 7df7023c2..675e76a95 100644
--- a/unit_tests/sources/declarative/partition_routers/test_substream_partition_router.py
+++ b/unit_tests/sources/declarative/partition_routers/test_substream_partition_router.py
@@ -475,16 +475,14 @@ def test_substream_partition_router_invalid_parent_record_type():
         ),
         # Case 7: Migrate child state to parent state but child state is empty
         (
-                {
-                    "state": {},
-                    "states": [],
-                    "parent_state": {
-                        "posts": {}
-                    },
-                    "lookback_window": 1,
-                    "use_global_cursor": False
-                },
-                {},
+            {
+                "state": {},
+                "states": [],
+                "parent_state": {"posts": {}},
+                "lookback_window": 1,
+                "use_global_cursor": False,
+            },
+            {},
         ),
     ],
     ids=[