fix: warn on empty value and decrypt failure in get_all variable listing (#13741)

Co-authored-by: Janardan S Kavia <janardanskavia@Janardans-MacBook-Pro.local>

src/backend/base/langflow/services/variable/service.py

@@ -238,9 +238,16 @@ class DatabaseVariableService(VariableService, Service):
         for variable in variables:
             value = None
             if variable.type == GENERIC_TYPE:
+                if not variable.value:
+                    await logger.awarning("Variable '%s' has no stored value — skipping.", variable.name)
+                    continue
                 value = auth_utils.decrypt_api_key(variable.value)
                 if not value:
-                    # If decryption fails (likely due to encryption by different key), skip this variable
+                    await logger.awarning(
+                        "Variable '%s' could not be decrypted — likely encrypted with a different "
+                        "LANGFLOW_SECRET_KEY. Skipping.",
+                        variable.name,
+                    )
                     continue
 
             # Model validate will set value to None if credential type

src/backend/tests/unit/services/variable/test_service.py

@@ -1,6 +1,6 @@
 import secrets
 from datetime import datetime
-from unittest.mock import patch
+from unittest.mock import AsyncMock, MagicMock, patch
 from uuid import uuid4
 
 import pytest
@@ -394,6 +394,67 @@ async def test_update_generic_variable_with_fernet_signature_fails(service, sess
         await service.update_variable(user_id, "TEST_VAR", "gAAAAABthis-looks-like-encrypted", session=session)
 
 
+async def test_get_all__empty_value_warns_and_skips(service, session: AsyncSession):
+    """get_all warns and skips GENERIC variables whose stored value is None or empty."""
+    user_id = uuid4()
+
+    # Create a normal generic variable, then manually blank its value to simulate a bad DB row.
+    var = await service.create_variable(user_id, "EMPTY_VAR", "initial", type_=GENERIC_TYPE, session=session)
+    var.value = ""
+    session.add(var)
+    await session.flush()
+
+    mock_logger = MagicMock()
+    mock_logger.awarning = AsyncMock()
+    with patch("langflow.services.variable.service.logger", mock_logger):
+        result = await service.get_all(user_id, session=session)
+
+    # Variable should be excluded from results.
+    assert not any(v.name == "EMPTY_VAR" for v in result)
+    # Warning must name the variable and mention empty value.
+    warning_calls = [str(c) for c in mock_logger.awarning.call_args_list]
+    assert any("EMPTY_VAR" in c for c in warning_calls)
+    assert any("no stored value" in c for c in warning_calls)
+
+
+async def test_get_all__decrypt_failure_warns_and_skips(service, session: AsyncSession):
+    """get_all warns with a key-mismatch message when decrypt returns empty for a non-empty value."""
+    user_id = uuid4()
+
+    await service.create_variable(user_id, "MY_VAR", "real_value", type_=GENERIC_TYPE, session=session)
+
+    mock_logger = MagicMock()
+    mock_logger.awarning = AsyncMock()
+    # Simulate decrypt returning "" (key mismatch) without touching the stored value.
+    with (
+        patch("langflow.services.variable.service.auth_utils.decrypt_api_key", return_value=""),
+        patch("langflow.services.variable.service.logger", mock_logger),
+    ):
+        result = await service.get_all(user_id, session=session)
+
+    # Variable should be excluded from results.
+    assert not any(v.name == "MY_VAR" for v in result)
+    # Warning must name the variable and mention SECRET_KEY.
+    warning_calls = [str(c) for c in mock_logger.awarning.call_args_list]
+    assert any("MY_VAR" in c for c in warning_calls)
+    assert any("SECRET_KEY" in c for c in warning_calls)
+
+
+async def test_get_all__healthy_generic_variable_included(service, session: AsyncSession):
+    """get_all includes GENERIC variables that decrypt successfully — no warnings emitted."""
+    user_id = uuid4()
+
+    await service.create_variable(user_id, "GOOD_VAR", "good_value", type_=GENERIC_TYPE, session=session)
+
+    mock_logger = MagicMock()
+    mock_logger.awarning = AsyncMock()
+    with patch("langflow.services.variable.service.logger", mock_logger):
+        result = await service.get_all(user_id, session=session)
+
+    assert any(v.name == "GOOD_VAR" for v in result)
+    mock_logger.awarning.assert_not_called()
+
+
 async def test_create_credential_variable_with_fernet_signature_succeeds(service, session: AsyncSession):
     """Test that CREDENTIAL variables can have values that look like Fernet tokens (they get encrypted anyway)."""
     user_id = uuid4()