Fix getattr in runnable binding for cases where config is passed in as arg too (#20528)

…s arg too

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libs/core/langchain_core/runnables/base.py

@@ -4895,14 +4895,36 @@ class RunnableBinding(RunnableBindingBase[Input, Output]):
     def __getattr__(self, name: str) -> Any:
         attr = getattr(self.bound, name)
 
-        if callable(attr) and accepts_config(attr):
+        if callable(attr) and (
+            config_param := inspect.signature(attr).parameters.get("config")
+        ):
+            if config_param.kind == inspect.Parameter.KEYWORD_ONLY:
 
                 @wraps(attr)
                 def wrapper(*args: Any, **kwargs: Any) -> Any:
                     return attr(
                         *args,
+                        config=merge_configs(self.config, kwargs.pop("config", None)),
+                        **kwargs,
+                    )
+
+                return wrapper
+            elif config_param.kind == inspect.Parameter.POSITIONAL_OR_KEYWORD:
+                idx = list(inspect.signature(attr).parameters).index("config")
+
+                @wraps(attr)
+                def wrapper(*args: Any, **kwargs: Any) -> Any:
+                    if len(args) >= idx + 1:
+                        argsl = list(args)
+                        argsl[idx] = merge_configs(self.config, argsl[idx])
+                        return attr(*argsl, **kwargs)
+                    else:
+                        return attr(
+                            *args,
+                            config=merge_configs(
+                                self.config, kwargs.pop("config", None)
+                            ),
                             **kwargs,
-                    config=merge_configs(self.config, kwargs.get("config")),
                         )
 
                 return wrapper

libs/core/langchain_core/runnables/graph.py

@@ -344,6 +344,7 @@ class Graph:
 
     def draw_mermaid(
         self,
+        *,
         curve_style: CurveStyle = CurveStyle.LINEAR,
         node_colors: NodeColors = NodeColors(
             start="#ffdfba", end="#baffc9", other="#fad7de"
@@ -372,6 +373,7 @@ class Graph:
 
     def draw_mermaid_png(
         self,
+        *,
         curve_style: CurveStyle = CurveStyle.LINEAR,
         node_colors: NodeColors = NodeColors(
             start="#ffdfba", end="#baffc9", other="#fad7de"

libs/core/langchain_core/runnables/graph_mermaid.py

@@ -14,6 +14,7 @@ from langchain_core.runnables.graph import (
 def draw_mermaid(
     nodes: Dict[str, str],
     edges: List[Edge],
+    *,
     first_node_label: Optional[str] = None,
     last_node_label: Optional[str] = None,
     curve_style: CurveStyle = CurveStyle.LINEAR,

libs/core/tests/unit_tests/runnables/test_configurable.py

@@ -34,7 +34,14 @@ class MyRunnable(RunnableSerializable[str, str]):
     def my_custom_function(self) -> str:
         return self.my_property
 
-    def my_custom_function_w_config(self, config: RunnableConfig) -> str:
+    def my_custom_function_w_config(
+        self, config: Optional[RunnableConfig] = None
+    ) -> str:
+        return self.my_property
+
+    def my_custom_function_w_kw_config(
+        self, *, config: Optional[RunnableConfig] = None
+    ) -> str:
         return self.my_property
 
 
@@ -175,7 +182,73 @@ def test_config_passthrough_nested() -> None:
             configurable={"my_property": "b"}
         ).my_custom_function()  # type: ignore[attr-defined]
         == "b"
+    ), "function without config can be called w bound config"
+    assert (
+        configurable_runnable.with_config(
+            configurable={"my_property": "b"}
+        ).my_custom_function_w_config(  # type: ignore[attr-defined]
         )
+        == "b"
+    ), "func with config arg can be called w bound config without config"
+    assert (
+        configurable_runnable.with_config(
+            configurable={"my_property": "b"}
+        ).my_custom_function_w_config(  # type: ignore[attr-defined]
+            config={"configurable": {"my_property": "c"}}
+        )
+        == "c"
+    ), "func with config arg can be called w bound config with config as kwarg"
+    assert (
+        configurable_runnable.with_config(
+            configurable={"my_property": "b"}
+        ).my_custom_function_w_kw_config(  # type: ignore[attr-defined]
+        )
+        == "b"
+    ), "function with config kwarg can be called w bound config w/out config"
+    assert (
+        configurable_runnable.with_config(
+            configurable={"my_property": "b"}
+        ).my_custom_function_w_kw_config(  # type: ignore[attr-defined]
+            config={"configurable": {"my_property": "c"}}
+        )
+        == "c"
+    ), "function with config kwarg can be called w bound config with config"
+    assert (
+        configurable_runnable.with_config(configurable={"my_property": "b"})
+        .with_types()
+        .my_custom_function()  # type: ignore[attr-defined]
+        == "b"
+    ), "function without config can be called w bound config"
+    assert (
+        configurable_runnable.with_config(configurable={"my_property": "b"})
+        .with_types()
+        .my_custom_function_w_config(  # type: ignore[attr-defined]
+        )
+        == "b"
+    ), "func with config arg can be called w bound config without config"
+    assert (
+        configurable_runnable.with_config(configurable={"my_property": "b"})
+        .with_types()
+        .my_custom_function_w_config(  # type: ignore[attr-defined]
+            config={"configurable": {"my_property": "c"}}
+        )
+        == "c"
+    ), "func with config arg can be called w bound config with config as kwarg"
+    assert (
+        configurable_runnable.with_config(configurable={"my_property": "b"})
+        .with_types()
+        .my_custom_function_w_kw_config(  # type: ignore[attr-defined]
+        )
+        == "b"
+    ), "function with config kwarg can be called w bound config w/out config"
+    assert (
+        configurable_runnable.with_config(configurable={"my_property": "b"})
+        .with_types()
+        .my_custom_function_w_kw_config(  # type: ignore[attr-defined]
+            config={"configurable": {"my_property": "c"}}
+        )
+        == "c"
+    ), "function with config kwarg can be called w bound config with config"
     # second one
     with pytest.raises(AttributeError):
         configurable_runnable.my_other_custom_function()  # type: ignore[attr-defined]