core[patch]: manually coerce ToolMessage args (#26283)

libs/community/langchain_community/document_loaders/html_bs.py

@@ -1,3 +1,4 @@
+import importlib.util
 import logging
 from pathlib import Path
 from typing import Dict, Iterator, Union
@@ -106,6 +107,13 @@ class BSHTMLLoader(BaseLoader):
         self.file_path = file_path
         self.open_encoding = open_encoding
         if bs_kwargs is None:
+            if not importlib.util.find_spec("lxml"):
+                raise ImportError(
+                    "By default BSHTMLLoader uses the 'lxml' package. Please either "
+                    "install it with `pip install -U lxml` or pass in init arg "
+                    "`bs_kwargs={'features': '...'}` to overwrite the default "
+                    "BeautifulSoup kwargs."
+                )
             bs_kwargs = {"features": "lxml"}
         self.bs_kwargs = bs_kwargs
         self.get_text_separator = get_text_separator

libs/core/langchain_core/messages/tool.py

@@ -1,7 +1,8 @@
 import json
 from typing import Any, Dict, List, Literal, Optional, Tuple, Union
+from uuid import UUID
 
-from pydantic import Field
+from pydantic import Field, model_validator
 from typing_extensions import NotRequired, TypedDict
 
 from langchain_core.messages.base import BaseMessage, BaseMessageChunk, merge_content
@@ -82,15 +83,48 @@ class ToolMessage(BaseMessage):
         Default is ["langchain", "schema", "messages"]."""
         return ["langchain", "schema", "messages"]
 
+    @model_validator(mode="before")
+    @classmethod
+    def coerce_args(cls, values: dict) -> dict:
+        content = values["content"]
+        if isinstance(content, tuple):
+            content = list(content)
+
+        if not isinstance(content, (str, list)):
+            try:
+                values["content"] = str(content)
+            except ValueError as e:
+                raise ValueError(
+                    "ToolMessage content should be a string or a list of string/dicts. "
+                    f"Received:\n\n{content=}\n\n which could not be coerced into a "
+                    "string."
+                ) from e
+        elif isinstance(content, list):
+            values["content"] = []
+            for i, x in enumerate(content):
+                if not isinstance(x, (str, dict)):
+                    try:
+                        values["content"].append(str(x))
+                    except ValueError as e:
+                        raise ValueError(
+                            "ToolMessage content should be a string or a list of "
+                            "string/dicts. Received a list but "
+                            f"element ToolMessage.content[{i}] is not a dict and could "
+                            f"not be coerced to a string.:\n\n{x}"
+                        ) from e
+                else:
+                    values["content"].append(x)
+        else:
+            pass
+
+        tool_call_id = values["tool_call_id"]
+        if isinstance(tool_call_id, UUID):
+            values["tool_call_id"] = str(tool_call_id)
+        return values
+
     def __init__(
         self, content: Union[str, List[Union[str, Dict]]], **kwargs: Any
     ) -> None:
-        """Pass in content as positional arg.
-
-        Args:
-            content: The string contents of the message.
-            kwargs: Additional fields to pass to the message
-        """
         super().__init__(content=content, **kwargs)
 
 

libs/core/tests/unit_tests/test_messages.py

@@ -1,8 +1,11 @@
 import unittest
+import uuid
 from typing import List, Type, Union
 
 import pytest
+from pydantic import ValidationError
 
+from langchain_core.documents import Document
 from langchain_core.load import dumpd, load
 from langchain_core.messages import (
     AIMessage,
@@ -980,3 +983,27 @@ def test_merge_content(
 ) -> None:
     actual = merge_content(first, *others)
     assert actual == expected
+
+
+def test_tool_message_content() -> None:
+    ToolMessage("foo", tool_call_id="1")
+    ToolMessage(["foo"], tool_call_id="1")
+    ToolMessage([{"foo": "bar"}], tool_call_id="1")
+
+    assert ToolMessage(("a", "b", "c"), tool_call_id="1").content == ["a", "b", "c"]  # type: ignore[arg-type]
+    assert ToolMessage(5, tool_call_id="1").content == "5"  # type: ignore[arg-type]
+    assert ToolMessage(5.1, tool_call_id="1").content == "5.1"  # type: ignore[arg-type]
+    assert ToolMessage({"foo": "bar"}, tool_call_id="1").content == "{'foo': 'bar'}"  # type: ignore[arg-type]
+    assert (
+        ToolMessage(Document("foo"), tool_call_id="1").content == "page_content='foo'"  # type: ignore[arg-type]
+    )
+
+
+def test_tool_message_tool_call_id() -> None:
+    ToolMessage("foo", tool_call_id="1")
+
+    # Currently we only handle UUID->str coercion manually.
+    ToolMessage("foo", tool_call_id=uuid.uuid4())
+
+    with pytest.raises(ValidationError):
+        ToolMessage("foo", tool_call_id=1)