refactor: deactivate caching if a component is part of a cycle (#3694)

* Set `_has_cycle_edges` to `True` for source and target vertices in cycle edges

* feat: Add `has_cycle_edges` method to Vertex class

The `has_cycle_edges` method is added to the `Vertex` class to check if the vertex has any cycle edges. Additionally, the `instantiate_component` method is updated to use the `initialize.loading.instantiate_class` function for custom component instantiation.

* Add `apply_on_outputs` method to Vertex for applying functions to outputs

* Add utility to find vertices in cycles within a directed graph

- Implement `find_cycle_vertices` function to identify all vertices that are part of cycles in a directed graph.
- Utilize depth-first search (DFS) to detect cycles and collect vertices involved in those cycles.

* Add unit tests for `find_cycle_vertices` utility function in graph module

* Add method to set cache for vertices in cycle

- Introduced `_set_cache_to_vertices_in_cycle` method to enable caching for vertices involved in cycles.
- Added `find_cycle_vertices` import to support the new method.
- Refactored vertex instantiation into `_instantiate_components_in_vertices` method for better code organization.

* refactor: Update caching logic for vertices in cycles

Refactor the `_set_cache_to_vertices_in_cycle` method to improve caching logic for vertices involved in cycles. Instead of setting the `cache` attribute to `True`, it is now set to `False` for better clarity and consistency. This change ensures that the cache is properly handled for vertices in cycles.

* Refactor `find_cycle_vertices` to use NetworkX for cycle detection

* Refactor `find_cycle_vertices` tests to remove entry point parameter and add new test case

- Removed the `entry_point` parameter from all test cases for `find_cycle_vertices`.
- Added a new parameterized test case `test_handle_two_inputs_in_cycle` to verify handling of cycles with two inputs.

* Disable cache in cycle: Update `apply_on_outputs` to handle empty outputs in `base.py`

* Add unit test to ensure output cache is disabled in graph cycles

* Add unit test for graph cyclicity with prompt components and OpenAI integration

- Introduce `test_updated_graph_with_prompts` to validate graph cyclicity and execution.
- Integrate `PromptComponent`, `OpenAIModelComponent`, and `ConditionalRouterComponent` in the test.
- Ensure graph execution with a maximum of 20 iterations and cache disabled.
- Validate the presence of expected output vertices in the results.

* Convert `_instantiate_components_in_vertices` to async and disable cache in cycle vertices

* Add default value handling for cycle edges in vertex component

- Introduced `default_value` to handle cases where edges are cycles and target parameters are present.
- Ensured that `default_value` is returned if defined, preventing errors when the component is not built.

* Switch from os.environ to os.getenv for API key retrieval in test_cycles.py

* Add __repr__ method to Edge class to indicate cycle edges with a symbol

* Refactor test_cycles.py to streamline component initialization and update assertions

- Simplified component initialization using method chaining.
- Corrected router input and message parameters to use openai_component_1.
- Updated assertions to check for correct output IDs.

* Refactor test_cycles.py to streamline component initialization and update assertions

* Refactor test to use custom serialization method instead of pickle

* Add cycle_vertices property to optimize cycle detection in graph

- Introduced `_cycle_vertices` attribute to store vertices involved in cycles.
- Added `cycle_vertices` property to compute and cache cycle vertices.
- Updated edge creation logic to use `cycle_vertices` for cycle detection.

* Enhance error message in `types.py` to include component ID for better debugging

* Refactor test_cycles.py to update graph configuration and assertions

- Changed router operator from "equals" to "contains".
- Consolidated chat output to a single component.
- Updated graph construction to use a single chat output.
- Replaced `_snapshot` with `get_snapshot` for graph state capture.
- Adjusted assertions to reflect the updated graph structure and outputs.

* Add api_key_required marker to test_updated_graph_with_prompts test

* Add validation to require max_iterations for cyclic graphs

* run ruff

- Refactored error message handling in `base.py` for cyclic graphs.
- Optimized cycle vertex extraction in `utils.py` by using set comprehension.

* Comment out tests for loading flow from JSON in test_loading.py

* Refactor test fixture for webhook flow creation in conftest.py

* Update unit tests to reflect new webhook flow structure in vertices endpoints

* Temporarily disable tests for loading Langchain objects with and without cached sessions

* Disable caching in vector store and OpenAI model components

src/backend/tests/conftest.py

@@ -12,13 +12,12 @@ from typing import TYPE_CHECKING
 import orjson
 import pytest
 from asgi_lifespan import LifespanManager
-from loguru import logger
-from pytest import LogCaptureFixture
-
 from base.langflow.components.inputs.ChatInput import ChatInput
 from dotenv import load_dotenv
 from fastapi.testclient import TestClient
 from httpx import ASGITransport, AsyncClient
+from loguru import logger
+from pytest import LogCaptureFixture
 from sqlmodel import Session, SQLModel, create_engine, select
 from sqlmodel.pool import StaticPool
 from tests.api_keys import get_openai_api_key
@@ -377,8 +376,8 @@ def json_two_outputs():
 
 
 @pytest.fixture
-async def added_flow_with_prompt_and_history(client, json_flow_with_prompt_and_history, logged_in_headers):
-    flow = orjson.loads(json_flow_with_prompt_and_history)
+async def added_flow_webhook_test(client, json_webhook_test, logged_in_headers):
+    flow = orjson.loads(json_webhook_test)
     data = flow["data"]
     flow = FlowCreate(name="Basic Chat", description="description", data=data)
     response = await client.post("api/v1/flows/", json=flow.model_dump(), headers=logged_in_headers)