chore: add deprecation warning to PGVector

langchain_postgres/vectorstores.py

@@ -416,6 +416,11 @@ def __init__(
                 doesn't exist. disabling creation is useful when using ReadOnly
                 Databases.
         """
+        warnings.warn(
+            "PGVector is deprecated. Please use PGVectorStore instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
         self.async_mode = async_mode
         self.embedding_function = embeddings
         self._embedding_length = embedding_length

tests/unit_tests/v1/test_deprecation.py

@@ -0,0 +1,31 @@
+
+import warnings
+from langchain_postgres.vectorstores import PGVector
+from tests.unit_tests.fake_embeddings import FakeEmbeddings
+
+def test_pgvector_deprecation_warning() -> None:
+    """Test that PGVector raises a DeprecationWarning on initialization."""
+    with warnings.catch_warnings(record=True) as w:
+        warnings.simplefilter("always")
+
+        # We expect initialization to fail due to missing connection/DB, 
+        # but the warning should be emitted *before* that.
+        # Or we can mock enough to make it succeed, but a try/except block 
+        # is safer if we want to avoid dependency on a running DB.
+        try:
+            PGVector(
+                embeddings=FakeEmbeddings(),
+                connection="postgresql://user:pass@localhost:5432/db",
+                collection_name="test_deprecation",
+                # Disable side effects that try to connect immediately
+                create_extension=False, 
+                # pre_delete_collection=False is default
+            )
+        except Exception:
+            # We don't care if it fails to connect, as long as it warned first
+            pass
+
+        # Check for the specific deprecation warning
+        assert len(w) > 0
+        assert issubclass(w[-1].category, DeprecationWarning)
+        assert "PGVector is deprecated" in str(w[-1].message)