Fix @odata.bind keys being lowercased in record payloads

_lowercase_keys() unconditionally lowercased all dictionary keys,
including @odata.bind keys which must retain PascalCase for the
navigation property name (e.g. new_CustomerId@odata.bind). This
caused 400 errors from Dataverse when creating or updating records
with lookup bindings via the SDK.

Keys containing @OData. are now preserved as-is.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: suyask-msft

src/PowerPlatform/Dataverse/data/_odata.py

@@ -96,10 +96,17 @@ def _lowercase_keys(record: Dict[str, Any]) -> Dict[str, Any]:
 
         Dataverse LogicalNames for attributes are stored lowercase, but users may
         provide PascalCase names (matching SchemaName). This normalizes the input.
+
+        Keys containing ``@odata.`` (e.g. ``new_CustomerId@odata.bind``) are
+        preserved as-is because the navigation property portion before ``@``
+        must retain its original casing (PascalCase SchemaName).
         """
         if not isinstance(record, dict):
             return record
-        return {k.lower() if isinstance(k, str) else k: v for k, v in record.items()}
+        return {
+            k.lower() if isinstance(k, str) and "@odata." not in k else k: v
+            for k, v in record.items()
+        }
 
     @staticmethod
     def _lowercase_list(items: Optional[List[str]]) -> Optional[List[str]]:

tests/unit/data/test_odata_internal.py

@@ -335,6 +335,23 @@ def test_record_keys_lowercased(self):
         self.assertIn("name", payload)
         self.assertNotIn("Name", payload)
 
+    def test_odata_bind_keys_preserve_case(self):
+        """@odata.bind keys must preserve PascalCase for navigation property."""
+        self.od._upsert(
+            "accounts", "account", {"accountnumber": "ACC-001"},
+            {
+                "Name": "Contoso",
+                "new_CustomerId@odata.bind": "/contacts(00000000-0000-0000-0000-000000000001)",
+            },
+        )
+        call = self._patch_call()
+        payload = call.kwargs["json"]
+        # Regular field is lowercased
+        self.assertIn("name", payload)
+        # @odata.bind key preserves original casing
+        self.assertIn("new_CustomerId@odata.bind", payload)
+        self.assertNotIn("new_customerid@odata.bind", payload)
+
     def test_returns_none(self):
         """_upsert always returns None."""
         result = self.od._upsert("accounts", "account", {"accountnumber": "ACC-001"}, {"name": "Contoso"})