Use an enum for configurable_alternatives to make the generated json schema nicer

libs/langchain/langchain/schema/runnable/base.py

@@ -129,9 +129,7 @@ def output_schema(self) -> Type[BaseModel]:
     def config_specs(self) -> Sequence[ConfigurableFieldSpec]:
         return []
 
-    def config_schema(
-        self, *, include: Optional[Sequence[str]] = None
-    ) -> Type[BaseModel]:
+    def config_schema(self, *, include: Sequence[str]) -> Type[BaseModel]:
         class _Config:
             arbitrary_types_allowed = True
 
@@ -150,7 +148,7 @@ class _Config:
                     for spec in config_specs
                 },
             )
-            if config_specs
+            if config_specs and "configurable" in include
             else None
         )
 
@@ -161,7 +159,7 @@ class _Config:
             **{
                 field_name: (field_type, None)
                 for field_name, field_type in RunnableConfig.__annotations__.items()
-                if field_name in include
+                if field_name in [i for i in include if i != "configurable"]
             },
         )
 
@@ -873,7 +871,7 @@ def configurable_fields(
                     "available keys are {self.__fields__.keys()}"
                 )
 
-        return RunnableConfigurableFields(bound=self, fields=kwargs)
+        return RunnableConfigurableFields(default=self, fields=kwargs)
 
     def configurable_alternatives(
         self,
@@ -885,7 +883,7 @@ def configurable_alternatives(
         )
 
         return RunnableConfigurableAlternatives(
-            which=which, bound=self, alternatives=kwargs
+            which=which, default=self, alternatives=kwargs
         )
 
 
@@ -2051,9 +2049,7 @@ def output_schema(self) -> type[BaseModel]:
     def config_specs(self) -> Sequence[ConfigurableFieldSpec]:
         return self.bound.config_specs
 
-    def config_schema(
-        self, *, include: Optional[Sequence[str]] = None
-    ) -> Type[BaseModel]:
+    def config_schema(self, *, include: Sequence[str]) -> Type[BaseModel]:
         return self.bound.config_schema(include=include)
 
     @classmethod
@@ -2132,9 +2128,7 @@ def output_schema(self) -> Type[BaseModel]:
     def config_specs(self) -> Sequence[ConfigurableFieldSpec]:
         return self.bound.config_specs
 
-    def config_schema(
-        self, *, include: Optional[Sequence[str]] = None
-    ) -> Type[BaseModel]:
+    def config_schema(self, *, include: Sequence[str]) -> Type[BaseModel]:
         return self.bound.config_schema(include=include)
 
     @classmethod

libs/langchain/langchain/schema/runnable/configurable.py

@@ -1,13 +1,13 @@
 from __future__ import annotations
 
+import enum
 from abc import abstractmethod
 from typing import (
     Any,
     AsyncIterator,
     Dict,
     Iterator,
     List,
-    Literal,
     Optional,
     Sequence,
     Type,
@@ -32,7 +32,7 @@
 
 
 class DynamicRunnable(RunnableSerializable[Input, Output]):
-    bound: RunnableSerializable[Input, Output]
+    default: RunnableSerializable[Input, Output]
 
     class Config:
         arbitrary_types_allowed = True
@@ -47,19 +47,19 @@ def get_lc_namespace(cls) -> List[str]:
 
     @property
     def InputType(self) -> Type[Input]:
-        return self.bound.InputType
+        return self.default.InputType
 
     @property
     def OutputType(self) -> Type[Output]:
-        return self.bound.OutputType
+        return self.default.OutputType
 
     @property
     def input_schema(self) -> Type[BaseModel]:
-        return self.bound.input_schema
+        return self.default.input_schema
 
     @property
     def output_schema(self) -> Type[BaseModel]:
-        return self.bound.output_schema
+        return self.default.output_schema
 
     @abstractmethod
     def _prepare(
@@ -88,8 +88,8 @@ def batch(
         configs = get_config_list(config, len(inputs))
         prepared = [self._prepare(c) for c in configs]
 
-        if all(p is self.bound for p in prepared):
-            return self.bound.batch(
+        if all(p is self.default for p in prepared):
+            return self.default.batch(
                 inputs, config, return_exceptions=return_exceptions, **kwargs
             )
 
@@ -131,8 +131,8 @@ async def abatch(
         configs = get_config_list(config, len(inputs))
         prepared = [self._prepare(c) for c in configs]
 
-        if all(p is self.bound for p in prepared):
-            return await self.bound.abatch(
+        if all(p is self.default for p in prepared):
+            return await self.default.abatch(
                 inputs, config, return_exceptions=return_exceptions, **kwargs
             )
 
@@ -202,18 +202,18 @@ def config_specs(self) -> Sequence[ConfigurableFieldSpec]:
                 id=spec.id,
                 name=spec.name,
                 description=spec.description
-                or self.bound.__fields__[field_name].field_info.description,
+                or self.default.__fields__[field_name].field_info.description,
                 annotation=spec.annotation
-                or self.bound.__fields__[field_name].annotation,
-                default=getattr(self.bound, field_name),
+                or self.default.__fields__[field_name].annotation,
+                default=getattr(self.default, field_name),
             )
             for field_name, spec in self.fields.items()
         ]
 
     def configurable_fields(
         self, **kwargs: ConfigurableField
     ) -> RunnableSerializable[Input, Output]:
-        return self.bound.configurable_fields(**{**self.fields, **kwargs})
+        return self.default.configurable_fields(**{**self.fields, **kwargs})
 
     def _prepare(
         self, config: Optional[RunnableConfig] = None
@@ -227,49 +227,56 @@ def _prepare(
         }
 
         if configurable:
-            return self.bound.__class__(**{**self.bound.dict(), **configurable})
+            return self.default.__class__(**{**self.default.dict(), **configurable})
         else:
-            return self.bound
+            return self.default
+
+
+# Before Python 3.11 native StrEnum is not available
+class StrEnum(str, enum.Enum):
+    pass
 
 
 class RunnableConfigurableAlternatives(DynamicRunnable[Input, Output]):
     which: ConfigurableField
 
     alternatives: Dict[str, RunnableSerializable[Input, Output]]
 
+    default_key: str = "default"
+
     @property
     def config_specs(self) -> Sequence[ConfigurableFieldSpec]:
-        alt_keys = self.alternatives.keys()
-        which_keys = tuple(Literal[k] for k in alt_keys) + (  # type: ignore
-            Literal["default"],
+        which_enum = StrEnum(  # type: ignore[call-overload]
+            self.which.name or self.which.id,
+            ((v, v) for v in list(self.alternatives.keys()) + [self.default_key]),
         )
         return [
             ConfigurableFieldSpec(
                 id=self.which.id,
                 name=self.which.name,
                 description=self.which.description,
-                annotation=Union[which_keys],  # type: ignore
-                default="default",
+                annotation=which_enum,
+                default=self.default_key,
             ),
-            *self.bound.config_specs,
+            *self.default.config_specs,
         ] + [s for alt in self.alternatives.values() for s in alt.config_specs]
 
     def configurable_fields(
         self, **kwargs: ConfigurableField
     ) -> RunnableSerializable[Input, Output]:
         return self.__class__(
             which=self.which,
-            bound=self.bound.configurable_fields(**kwargs),
+            default=self.default.configurable_fields(**kwargs),
             alternatives=self.alternatives,
         )
 
     def _prepare(
         self, config: Optional[RunnableConfig] = None
     ) -> Runnable[Input, Output]:
         config = config or {}
-        which = config.get("configurable", {}).get(self.which.id)
-        if not which:
-            return self.bound
+        which = str(config.get("configurable", {}).get(self.which.id, self.default_key))
+        if which == self.default_key:
+            return self.default
         elif which in self.alternatives:
             return self.alternatives[which]
         else:

libs/langchain/langchain/schema/runnable/fallbacks.py

@@ -69,9 +69,7 @@ def config_specs(self) -> Sequence[ConfigurableFieldSpec]:
             for spec in step.config_specs
         )
 
-    def config_schema(
-        self, *, include: Optional[Sequence[str]] = None
-    ) -> Type[BaseModel]:
+    def config_schema(self, *, include: Sequence[str]) -> Type[BaseModel]:
         return self.runnable.config_schema(include=include)
 
     @classmethod

libs/langchain/tests/unit_tests/schema/runnable/test_runnable.py

@@ -563,7 +563,7 @@ def test_configurable_fields() -> None:
 
     assert fake_llm_configurable.invoke("...") == "a"
 
-    assert fake_llm_configurable.config_schema().schema() == {
+    assert fake_llm_configurable.config_schema(include=["configurable"]).schema() == {
         "title": "RunnableConfigurableFieldsConfig",
         "type": "object",
         "properties": {"configurable": {"$ref": "#/definitions/Configurable"}},
@@ -606,7 +606,7 @@ def test_configurable_fields() -> None:
         text="Hello, John!"
     )
 
-    assert prompt_configurable.config_schema().schema() == {
+    assert prompt_configurable.config_schema(include=["configurable"]).schema() == {
         "title": "RunnableConfigurableFieldsConfig",
         "type": "object",
         "properties": {"configurable": {"$ref": "#/definitions/Configurable"}},
@@ -638,7 +638,7 @@ def test_configurable_fields() -> None:
 
     assert chain_configurable.invoke({"name": "John"}) == "a"
 
-    assert chain_configurable.config_schema().schema() == {
+    assert chain_configurable.config_schema(include=["configurable"]).schema() == {
         "title": "RunnableSequenceConfig",
         "type": "object",
         "properties": {"configurable": {"$ref": "#/definitions/Configurable"}},
@@ -690,7 +690,9 @@ def test_configurable_fields() -> None:
         "llm3": "a",
     }
 
-    assert chain_with_map_configurable.config_schema().schema() == {
+    assert chain_with_map_configurable.config_schema(
+        include=["configurable"]
+    ).schema() == {
         "title": "RunnableSequenceConfig",
         "type": "object",
         "properties": {"configurable": {"$ref": "#/definitions/Configurable"}},
@@ -760,22 +762,25 @@ def test_configurable_fields_example() -> None:
 
     assert chain_configurable.invoke({"name": "John"}) == "a"
 
-    assert chain_configurable.config_schema().schema() == {
+    assert chain_configurable.config_schema(include=["configurable"]).schema() == {
         "title": "RunnableSequenceConfig",
         "type": "object",
         "properties": {"configurable": {"$ref": "#/definitions/Configurable"}},
         "definitions": {
+            "LLM": {
+                "title": "LLM",
+                "description": "An enumeration.",
+                "enum": ["chat", "default"],
+                "type": "string",
+            },
             "Configurable": {
                 "title": "Configurable",
                 "type": "object",
                 "properties": {
                     "llm": {
                         "title": "LLM",
                         "default": "default",
-                        "anyOf": [
-                            {"enum": ["chat"], "type": "string"},
-                            {"enum": ["default"], "type": "string"},
-                        ],
+                        "allOf": [{"$ref": "#/definitions/LLM"}],
                     },
                     "llm_responses": {
                         "title": "LLM Responses",
@@ -791,7 +796,7 @@ def test_configurable_fields_example() -> None:
                         "type": "string",
                     },
                 },
-            }
+            },
         },
     }