fix: update message reload and update langchain-core (#3054)

* refactor: update langchain-core to version 0.2.24

* refactor: convert inner messages to BaseMessage in load_lc_prompt method

* refactor: update ChatPromptTemplate instantiation in message.py

* refactor: update langflow-base dependency to use local path for development

* [autofix.ci] apply automated fixes

* refactor: update ChatPromptTemplate instantiation in message.py

* refactor: add async_from_template_and_variables and sync from_template_and_variables

* feat(tests): add unit test for Message schema serialization and prompt loading

* refactor: update langchain-core dependency to version 0.2.24

* chore: new lock

* mypy

* chore: format pyproject

* refactor: rename async_from_template_and_variables to from_template_and_variables in Message class

* refactor: Rename async_from_template_and_variables to from_template_and_variables in Message class

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Nicolò Boschi <[email protected]>

pyproject.toml

@@ -27,7 +27,7 @@ langflow = "langflow.__main__:main"
 
 [tool.poetry.dependencies]
 python = ">=3.10,<3.13"
-langflow-base = { path = "./src/backend/base", develop = true }
+langflow-base ={ path = "./src/backend/base", develop = true }
 beautifulsoup4 = "^4.12.2"
 google-search-results = "^2.4.1"
 google-api-python-client = "^2.130.0"

src/backend/base/langflow/graph/graph/base.py

@@ -1014,7 +1014,7 @@ async def get_next_runnable_vertices(self, lock: asyncio.Lock, vertex: "Vertex",
                 else:
                     self.run_manager.add_to_vertices_being_run(next_v_id)
             if cache and self.flow_id:
-                set_cache_coro = partial(get_chat_service().set_cache, key=self.flow_id)
+                set_cache_coro = partial(get_chat_service().set_cache, self.flow_id)
                 await set_cache_coro(self, lock)
         return next_runnable_vertices
 

src/backend/base/langflow/schema/message.py

@@ -1,3 +1,4 @@
+import asyncio
 from datetime import datetime, timezone
 from typing import Annotated, Any, AsyncIterator, Iterator, List, Optional
 from uuid import UUID
@@ -15,10 +16,10 @@
 from langflow.schema.data import Data
 from langflow.schema.image import Image, get_file_paths, is_image_file
 from langflow.utils.constants import (
-    MESSAGE_SENDER_USER,
-    MESSAGE_SENDER_NAME_USER,
-    MESSAGE_SENDER_NAME_AI,
     MESSAGE_SENDER_AI,
+    MESSAGE_SENDER_NAME_AI,
+    MESSAGE_SENDER_NAME_USER,
+    MESSAGE_SENDER_USER,
 )
 
 
@@ -171,20 +172,23 @@ async def get_file_content_dicts(self):
     def load_lc_prompt(self):
         if "prompt" not in self:
             raise ValueError("Prompt is required.")
-        loaded_prompt = load(self.prompt)
-        # Rebuild HumanMessages if they are instance of BaseMessage
-        if isinstance(loaded_prompt, ChatPromptTemplate):
-            messages = []
-            for message in loaded_prompt.messages:
-                if isinstance(message, HumanMessage):
+        # self.prompt was passed through jsonable_encoder
+        # so inner messages are not BaseMessage
+        # we need to convert them to BaseMessage
+        messages = []
+        for message in self.prompt.get("kwargs", {}).get("messages", []):
+            match message:
+                case HumanMessage():
                     messages.append(message)
-                elif message.type == "human":
-                    messages.append(HumanMessage(content=message.content))
-                elif message.type == "system":
-                    messages.append(SystemMessage(content=message.content))
-                elif message.type == "ai":
-                    messages.append(AIMessage(content=message.content))
-            loaded_prompt.messages = messages
+                case _ if message.get("type") == "human":
+                    messages.append(HumanMessage(content=message.get("content")))
+                case _ if message.get("type") == "system":
+                    messages.append(SystemMessage(content=message.get("content")))
+                case _ if message.get("type") == "ai":
+                    messages.append(AIMessage(content=message.get("content")))
+
+        self.prompt["kwargs"]["messages"] = messages
+        loaded_prompt = load(self.prompt)
         return loaded_prompt
 
     @classmethod
@@ -216,7 +220,17 @@ async def from_template_and_variables(cls, template: str, **variables):
         if contents:
             message = HumanMessage(content=[{"type": "text", "text": text}] + contents)
 
-        prompt_template = ChatPromptTemplate.from_messages([message])  # type: ignore
+        prompt_template = ChatPromptTemplate(messages=[message])  # type: ignore
         instance.prompt = jsonable_encoder(prompt_template.to_json())
         instance.messages = instance.prompt.get("kwargs", {}).get("messages", [])
         return instance
+
+    @classmethod
+    def sync_from_template_and_variables(cls, template: str, **variables):
+        # Run the async version in a sync way
+        try:
+            loop = asyncio.get_running_loop()
+        except RuntimeError:
+            return asyncio.run(cls.from_template_and_variables(template, **variables))
+        else:
+            return loop.run_until_complete(cls.from_template_and_variables(template, **variables))

src/backend/base/pyproject.toml

@@ -32,7 +32,7 @@ httpx = "*"
 uvicorn = "^0.30.0"
 gunicorn = "^22.0.0"
 langchain = "~0.2.0"
-langchain-core = "0.2.23"
+langchain-core = "^0.2.24"
 langchainhub = "~0.1.15"
 sqlmodel = "^0.0.18"
 loguru = "^0.7.1"

src/backend/tests/unit/schema/test_schema_message.py

@@ -0,0 +1,30 @@
+import pytest
+from langchain_core.prompts.chat import ChatPromptTemplate
+
+from langflow.schema.message import Message
+
+
+@pytest.fixture
+def client():
+    pass
+
+
+@pytest.mark.asyncio
+async def test_message_async_prompt_serialization():
+    template = "Hello, {name}!"
+    message = await Message.from_template_and_variables(template, name="Langflow")
+    assert message.text == "Hello, Langflow!"
+
+    prompt = message.load_lc_prompt()
+    assert isinstance(prompt, ChatPromptTemplate)
+    assert prompt.messages[0].content == "Hello, Langflow!"
+
+
+def test_message_prompt_serialization():
+    template = "Hello, {name}!"
+    message = Message.sync_from_template_and_variables(template, name="Langflow")
+    assert message.text == "Hello, Langflow!"
+
+    prompt = message.load_lc_prompt()
+    assert isinstance(prompt, ChatPromptTemplate)
+    assert prompt.messages[0].content == "Hello, Langflow!"