feat: centralize global variable management (#3284)

* test: add tests for global variable endpoints

* test: add unit tests variable service

* fix: anticipate checks to prevent the code from breaking

* feat: add a new method to interface

* feat: add method to update fields in variable service

* feat: replace variable api code

* fix: mypy error

* fix: mypy error

* feat(variable): Allow deleting variables by name or ID in DatabaseVariableService.

* refactor(api): Simplify delete method in variable router.

---------

Co-authored-by: Gabriel Luiz Freitas Almeida <gabriel@langflow.org>

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

@@ -0,0 +1,219 @@
+from langflow.services.database.models.variable.model import VariableUpdate
+import pytest
+from unittest.mock import patch
+from uuid import uuid4
+from datetime import datetime
+from sqlmodel import SQLModel, Session, create_engine
+from langflow.services.deps import get_settings_service
+from langflow.services.variable.service import GENERIC_TYPE, CREDENTIAL_TYPE, DatabaseVariableService
+
+
+@pytest.fixture
+def client():
+    pass
+
+
+@pytest.fixture
+def service():
+    settings_service = get_settings_service()
+    return DatabaseVariableService(settings_service)
+
+
+@pytest.fixture
+def session():
+    engine = create_engine("sqlite:///:memory:")
+    SQLModel.metadata.create_all(engine)
+    with Session(engine) as session:
+        yield session
+
+
+def test_initialize_user_variables__donkey(service, session):
+    user_id = uuid4()
+    name = "OPENAI_API_KEY"
+    value = "donkey"
+    service.initialize_user_variables(user_id, session=session)
+    result = service.create_variable(user_id, "OPENAI_API_KEY", "donkey", session=session)
+    new_service = DatabaseVariableService(get_settings_service())
+    new_service.initialize_user_variables(user_id, session=session)
+
+    result = new_service.get_variable(user_id, name, "", session=session)
+
+    assert result != value
+
+
+def test_initialize_user_variables__not_found_variable(service, session):
+    with patch("langflow.services.variable.service.DatabaseVariableService.create_variable") as m:
+        m.side_effect = Exception()
+        service.initialize_user_variables(uuid4(), session=session)
+
+    assert True
+
+
+def test_initialize_user_variables__skipping_environment_variable_storage(service, session):
+    service.settings_service.settings.store_environment_variables = False
+    service.initialize_user_variables(uuid4(), session=session)
+    assert True
+
+
+def test_get_variable(service, session):
+    user_id = uuid4()
+    name = "name"
+    value = "value"
+    field = ""
+    service.create_variable(user_id, name, value, session=session)
+
+    result = service.get_variable(user_id, name, field, session=session)
+
+    assert result == value
+
+
+def test_get_variable__ValueError(service, session):
+    user_id = uuid4()
+    name = "name"
+    field = ""
+
+    with pytest.raises(ValueError) as exc:
+        service.get_variable(user_id, name, field, session)
+
+    assert name in str(exc.value)
+    assert "variable not found" in str(exc.value)
+
+
+def test_get_variable__TypeError(service, session):
+    user_id = uuid4()
+    name = "name"
+    value = "value"
+    field = "session_id"
+    _type = CREDENTIAL_TYPE
+    service.create_variable(user_id, name, value, _type=_type, session=session)
+
+    with pytest.raises(TypeError) as exc:
+        service.get_variable(user_id, name, field, session)
+
+    assert name in str(exc.value)
+    assert "purpose is to prevent the exposure of value" in str(exc.value)
+
+
+def test_list_variables(service, session):
+    user_id = uuid4()
+    names = ["name1", "name2", "name3"]
+    value = "value"
+    for name in names:
+        service.create_variable(user_id, name, value, session=session)
+
+    result = service.list_variables(user_id, session=session)
+
+    assert all(name in result for name in names)
+
+
+def test_list_variables__empty(service, session):
+    result = service.list_variables(uuid4(), session=session)
+
+    assert not result
+    assert isinstance(result, list)
+
+
+def test_update_variable(service, session):
+    user_id = uuid4()
+    name = "name"
+    old_value = "old_value"
+    new_value = "new_value"
+    field = ""
+    service.create_variable(user_id, name, old_value, session=session)
+
+    old_recovered = service.get_variable(user_id, name, field, session=session)
+    result = service.update_variable(user_id, name, new_value, session=session)
+    new_recovered = service.get_variable(user_id, name, field, session=session)
+
+    assert old_value == old_recovered
+    assert new_value == new_recovered
+    assert result.user_id == user_id
+    assert result.name == name
+    assert result.value != old_value
+    assert result.value != new_value
+    assert result.default_fields == []
+    assert result.type == GENERIC_TYPE
+    assert isinstance(result.created_at, datetime)
+    assert isinstance(result.updated_at, datetime)
+
+
+def test_update_variable__ValueError(service, session):
+    user_id = uuid4()
+    name = "name"
+    value = "value"
+
+    with pytest.raises(ValueError) as exc:
+        service.update_variable(user_id, name, value, session=session)
+
+    assert name in str(exc.value)
+    assert "variable not found" in str(exc.value)
+
+
+def test_update_variable_fields(service, session):
+    user_id = uuid4()
+    variable = service.create_variable(user_id, "old_name", "old_value", session=session)
+    saved = variable.model_dump()
+    variable = VariableUpdate(**saved)
+    variable.name = "new_name"
+    variable.value = "new_value"
+    variable.default_fields = ["new_field"]
+
+    result = service.update_variable_fields(
+        user_id=user_id,
+        variable_id=saved.get("id"),
+        variable=variable,
+        session=session,
+    )
+
+    assert saved.get("id") == result.id
+    assert saved.get("user_id") == result.user_id
+    assert saved.get("name") != result.name
+    assert saved.get("value") != result.value
+    assert saved.get("default_fields") != result.default_fields
+    assert saved.get("type") == result.type
+    assert saved.get("created_at") == result.created_at
+    assert saved.get("updated_at") != result.updated_at
+
+
+def test_delete_variable(service, session):
+    user_id = uuid4()
+    name = "name"
+    value = "value"
+    field = ""
+
+    saved = service.create_variable(user_id, name, value, session=session)
+    recovered = service.get_variable(user_id, name, field, session=session)
+    service.delete_variable(user_id, name, session=session)
+    with pytest.raises(ValueError) as exc:
+        service.get_variable(user_id, name, field, session)
+
+    assert recovered == value
+    assert name in str(exc.value)
+    assert "variable not found" in str(exc.value)
+
+
+def test_delete_variable__ValueError(service, session):
+    user_id = uuid4()
+    name = "name"
+
+    with pytest.raises(ValueError) as exc:
+        service.delete_variable(user_id, name, session=session)
+
+    assert name in str(exc.value)
+    assert "variable not found" in str(exc.value)
+
+
+def test_create_variable(service, session):
+    user_id = uuid4()
+    name = "name"
+    value = "value"
+
+    result = service.create_variable(user_id, name, value, session=session)
+
+    assert result.user_id == user_id
+    assert result.name == name
+    assert result.value != value
+    assert result.default_fields == []
+    assert result.type == GENERIC_TYPE
+    assert isinstance(result.created_at, datetime)
+    assert isinstance(result.updated_at, datetime)