fix(low-code): Add parent state migration from global state (#322)

Author: tolik0

airbyte_cdk/sources/declarative/partition_routers/substream_partition_router.py

@@ -299,23 +299,33 @@ def set_initial_state(self, stream_state: StreamState) -> None:
 
     def _migrate_child_state_to_parent_state(self, stream_state: StreamState) -> StreamState:
         """
-        Migrate the child stream state to the parent stream's state format.
+        Migrate the child or global stream state into the parent stream's state format.
 
-        This method converts the global or child state into a format compatible with parent
-        streams. The migration occurs only for parent streams with incremental dependencies.
-        The method filters out per-partition states and retains only the global state in the
-        format `{cursor_field: cursor_value}`.
+        This method converts the child stream state—or, if present, the global state—into a format that is
+        compatible with parent streams that use incremental synchronization. The migration occurs only for
+        parent streams with incremental dependencies. It filters out per-partition states and retains only the
+        global state in the form {cursor_field: cursor_value}.
+
+        The method supports multiple input formats:
+          - A simple global state, e.g.:
+                {"updated_at": "2023-05-27T00:00:00Z"}
+          - A state object that contains a "state" key (which is assumed to hold the global state), e.g.:
+                {"state": {"updated_at": "2023-05-27T00:00:00Z"}, ...}
+            In this case, the migration uses the first value from the "state" dictionary.
+          - Any per-partition state formats or other non-simple structures are ignored during migration.
 
         Args:
             stream_state (StreamState): The state to migrate. Expected formats include:
                 - {"updated_at": "2023-05-27T00:00:00Z"}
-                - {"states": [...] } (ignored during migration)
+                - {"state": {"updated_at": "2023-05-27T00:00:00Z"}, ...}
+                  (In this format, only the first global state value is used, and per-partition states are ignored.)
 
         Returns:
             StreamState: A migrated state for parent streams in the format:
                 {
                     "parent_stream_name": {"parent_stream_cursor": "2023-05-27T00:00:00Z"}
                 }
+            where each parent stream with an incremental dependency is assigned its corresponding cursor value.
 
         Example:
             Input: {"updated_at": "2023-05-27T00:00:00Z"}
@@ -326,11 +336,15 @@ def _migrate_child_state_to_parent_state(self, stream_state: StreamState) -> Str
         substream_state_values = list(stream_state.values())
         substream_state = substream_state_values[0] if substream_state_values else {}
 
-        # Ignore per-partition states or invalid formats
+        # Ignore per-partition states or invalid formats.
         if isinstance(substream_state, (list, dict)) or len(substream_state_values) != 1:
-            return {}
+            # 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):
+                substream_state = list(stream_state["state"].values())[0]
+            else:
+                return {}
 
-        # Copy child state to parent streams with incremental dependencies
+        # Build the parent state for all parent streams with incremental dependencies.
         parent_state = {}
         if substream_state:
             for parent_config in self.parent_stream_configs:

unit_tests/sources/declarative/incremental/test_concurrent_perpartitioncursor.py

@@ -1450,8 +1450,19 @@ def test_incremental_parent_state(
             },
             STATE_MIGRATION_GLOBAL_EXPECTED_STATE,
         ),
+        (
+            {
+                "state": {"created_at": PARTITION_SYNC_START_TIME},
+            },
+            STATE_MIGRATION_EXPECTED_STATE,
+        ),
+    ],
+    ids=[
+        "legacy_python_format",
+        "low_code_per_partition_state",
+        "low_code_global_format",
+        "global_state_no_parent",
     ],
-    ids=["legacy_python_format", "low_code_per_partition_state", "low_code_global_format"],
 )
 def test_incremental_parent_state_migration(
     test_name, manifest, mock_requests, expected_records, initial_state, expected_state

unit_tests/sources/declarative/partition_routers/test_substream_partition_router.py

@@ -415,7 +415,7 @@ def test_substream_partition_router_invalid_parent_record_type():
         # Case 3: Initial state with global `state`, no migration expected
         (
             {"state": {"updated": "2023-05-27T00:00:00Z"}},
-            {},
+            {"parent_stream_cursor": "2023-05-27T00:00:00Z"},
         ),
         # Case 4: Initial state with per-partition `states`, no migration expected
         (
@@ -471,7 +471,7 @@ def test_substream_partition_router_invalid_parent_record_type():
                 "use_global_cursor": True,
                 "state": {"updated": "2023-05-27T00:00:00Z"},
             },
-            {},
+            {"parent_stream_cursor": "2023-05-27T00:00:00Z"},
         ),
     ],
     ids=[