catch exceptions properly

libs/core/langchain_core/tools/base.py

@@ -239,15 +239,6 @@ class ToolException(Exception):
     pass
 
 
-def convert_exception_to_tool_exception(e: Exception) -> ToolException:
-    tool_e = ToolException()
-    tool_e.args = e.args
-    tool_e.__cause__ = e.__cause__
-    tool_e.__context__ = e.__context__
-    tool_e.__traceback__ = e.__traceback__
-    return tool_e
-
-
 class BaseTool(RunnableSerializable[Union[str, Dict, ToolCall], Any]):
     """Interface LangChain tools must implement."""
 
@@ -551,6 +542,7 @@ class ChildTool(BaseTool):
         content = None
         artifact = None
         error_to_raise: Union[Exception, KeyboardInterrupt, None] = None
+        try:
             try:
                 child_config = patch_config(config, callbacks=run_manager.get_child())
                 context = copy_context()
@@ -578,18 +570,27 @@ class ChildTool(BaseTool):
                 if not self.handle_validation_error:
                     error_to_raise = e
                 else:
-                content = _handle_validation_error(e, flag=self.handle_validation_error)
+                    content = _handle_validation_error(
+                        e, flag=self.handle_validation_error
+                    )
                 status = "error"
-        except Exception as e:
+            except ToolException as e:
                 if not self.handle_tool_error:
                     error_to_raise = e
                 else:
-                e = convert_exception_to_tool_exception(e)
                     content = _handle_tool_error(e, flag=self.handle_tool_error)
                 status = "error"
+            except Exception as e:
+                raise ToolException(str(e)) from e
             except KeyboardInterrupt as e:
                 error_to_raise = e
                 status = "error"
+        except ToolException as e:
+            if not self.handle_tool_error:
+                error_to_raise = e
+            else:
+                content = _handle_tool_error(e, flag=self.handle_tool_error)
+            status = "error"
 
         if error_to_raise:
             run_manager.on_tool_error(error_to_raise)
@@ -661,6 +662,7 @@ class ChildTool(BaseTool):
         content = None
         artifact = None
         error_to_raise: Optional[Union[Exception, KeyboardInterrupt]] = None
+        try:
             try:
                 tool_args, tool_kwargs = self._to_args_and_kwargs(tool_input)
                 child_config = patch_config(config, callbacks=run_manager.get_child())
@@ -695,18 +697,27 @@ class ChildTool(BaseTool):
                 if not self.handle_validation_error:
                     error_to_raise = e
                 else:
-                content = _handle_validation_error(e, flag=self.handle_validation_error)
+                    content = _handle_validation_error(
+                        e, flag=self.handle_validation_error
+                    )
                 status = "error"
-        except Exception as e:
+            except ToolException as e:
                 if not self.handle_tool_error:
                     error_to_raise = e
                 else:
-                e = convert_exception_to_tool_exception(e)
                     content = _handle_tool_error(e, flag=self.handle_tool_error)
                 status = "error"
+            except Exception as e:
+                raise ToolException(str(e)) from e
             except KeyboardInterrupt as e:
                 error_to_raise = e
                 status = "error"
+        except ToolException as e:
+            if not self.handle_tool_error:
+                error_to_raise = e
+            else:
+                content = _handle_tool_error(e, flag=self.handle_tool_error)
+            status = "error"
 
         if error_to_raise:
             await run_manager.on_tool_error(error_to_raise)

libs/core/tests/unit_tests/test_tools.py

@@ -679,7 +679,7 @@ def test_exception_handling_callable() -> None:
 
 def test_exception_handling_non_tool_exception() -> None:
     _tool = _FakeExceptionTool(exception=ValueError())
-    with pytest.raises(ValueError):
+    with pytest.raises(ToolException):
         _tool.run({})
 
 
@@ -710,7 +710,7 @@ async def test_async_exception_handling_callable() -> None:
 
 async def test_async_exception_handling_non_tool_exception() -> None:
     _tool = _FakeExceptionTool(exception=ValueError())
-    with pytest.raises(ValueError):
+    with pytest.raises(ToolException):
         await _tool.arun({})
 
 
@@ -806,7 +806,7 @@ def test_validation_error_handling_non_validation_error(
             return "dummy"
 
     _tool = _RaiseNonValidationErrorTool(handle_validation_error=handler)  # type: ignore[call-arg]
-    with pytest.raises(NotImplementedError):
+    with pytest.raises(ToolException):
         _tool.run({})
 
 
@@ -868,7 +868,7 @@ async def test_async_validation_error_handling_non_validation_error(
             return "dummy"
 
     _tool = _RaiseNonValidationErrorTool(handle_validation_error=handler)  # type: ignore[call-arg]
-    with pytest.raises(NotImplementedError):
+    with pytest.raises(ToolException):
         await _tool.arun({})
 
 
@@ -1408,10 +1408,8 @@ def test_tool_injected_arg_without_schema(tool_: BaseTool) -> None:
     assert tool_.invoke(
         {"name": "foo", "args": {"x": 5, "y": "bar"}, "id": "123", "type": "tool_call"}
     ) == ToolMessage("bar", tool_call_id="123", name="foo")
-    expected_error = (
+
-        ValidationError if not isinstance(tool_, InjectedTool) else TypeError
+    with pytest.raises(ToolException):
-    )
-    with pytest.raises(expected_error):
         tool_.invoke({"x": 5})
 
     assert convert_to_openai_function(tool_) == {
@@ -1873,7 +1871,6 @@ def test__get_all_basemodel_annotations_v1() -> None:
 def test_tool_args_schema_pydantic_v2_with_metadata() -> None:
     from pydantic import BaseModel as BaseModelV2  # pydantic: ignore
     from pydantic import Field as FieldV2  # pydantic: ignore
-    from pydantic import ValidationError as ValidationErrorV2  # pydantic: ignore
 
     class Foo(BaseModelV2):
         x: List[int] = FieldV2(
@@ -1903,7 +1900,7 @@ def test_tool_args_schema_pydantic_v2_with_metadata() -> None:
     }
 
     assert foo.invoke({"x": [0] * 10})
-    with pytest.raises(ValidationErrorV2):
+    with pytest.raises(ToolException):
         foo.invoke({"x": [0] * 9})