community: use correct id_key when deleting by id in LanceDB wrapper (#28655)

- **Description:** The current version of the `delete` method assumes
that the id field will always be called `id`.
- **Issue:** n/a
- **Dependencies:** n/a
- **Twitter handle:** ugh, Twitter :D 

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---------

Co-authored-by: Erick Friis <erick@langchain.dev>

libs/community/langchain_community/vectorstores/lancedb.py

@@ -676,7 +676,7 @@ class LanceDB(VectorStore):
         if filter:
             tbl.delete(filter)
         elif ids:
-            tbl.delete("id in ('{}')".format(",".join(ids)))
+            tbl.delete(f"{self._id_key} in ('{{}}')".format(",".join(ids)))
         elif drop_columns:
             if self.api_key is not None:
                 raise NotImplementedError(

libs/community/tests/integration_tests/vectorstores/test_lancedb.py

@@ -84,6 +84,16 @@ def test_lancedb_delete() -> None:
     assert store.get_table().count_rows() == 2
 
 
+@pytest.mark.requires("lancedb")
+def test_lancedb_delete_by_ids() -> None:
+    embeddings = FakeEmbeddings()
+
+    store = LanceDB(embedding=embeddings, id_key="pk")
+    ids = store.add_texts(["text 1", "text 2", "item 3"])
+    store.delete(ids=ids)
+    assert store.get_table().count_rows() == 0
+
+
 @pytest.mark.requires("lancedb")
 def test_lancedb_all_searches() -> None:
     embeddings = FakeEmbeddings()