feat: support modifying field metadata in lancedb python (#2178)

python/python/lancedb/table.py

@@ -2405,6 +2405,19 @@ class LanceTable(Table):
         """
         LOOP.run(self._table.migrate_v2_manifest_paths())
 
+    def replace_field_metadata(self, field_name: str, new_metadata: Dict[str, str]):
+        """
+        Replace the metadata of a field in the schema
+
+        Parameters
+        ----------
+        field_name: str
+            The name of the field to replace the metadata for
+        new_metadata: dict
+            The new metadata to set
+        """
+        LOOP.run(self._table.replace_field_metadata(field_name, new_metadata))
+
 
 def _handle_bad_vectors(
     reader: pa.RecordBatchReader,
@@ -3635,6 +3648,21 @@ class AsyncTable:
         """
         await self._inner.migrate_manifest_paths_v2()
 
+    async def replace_field_metadata(
+        self, field_name: str, new_metadata: dict[str, str]
+    ):
+        """
+        Replace the metadata of a field in the schema
+
+        Parameters
+        ----------
+        field_name: str
+            The name of the field to replace the metadata for
+        new_metadata: dict
+            The new metadata to set
+        """
+        await self._inner.replace_field_metadata(field_name, new_metadata)
+
 
 @dataclass
 class IndexStatistics:

python/python/tests/test_table.py

@@ -1481,3 +1481,12 @@ async def test_optimize_delete_unverified(tmp_db_async: AsyncConnection, tmp_pat
         cleanup_older_than=timedelta(seconds=0), delete_unverified=True
     )
     assert stats.prune.old_versions_removed == 2
+
+
+def test_replace_field_metadata(tmp_path):
+    db = lancedb.connect(tmp_path)
+    table = db.create_table("my_table", data=[{"x": 0}])
+    table.replace_field_metadata("x", {"foo": "bar"})
+    schema = table.schema
+    field = schema[0].metadata
+    assert field == {b"foo": b"bar"}