Fix .dict() for agent/chain (#11436)

<!-- Thank you for contributing to LangChain!

Replace this entire comment with:
  - **Description:** a description of the change, 
  - **Issue:** the issue # it fixes (if applicable),
  - **Dependencies:** any dependencies required for this change,
- **Tag maintainer:** for a quicker response, tag the relevant
maintainer (see below),
- **Twitter handle:** we announce bigger features on Twitter. If your PR
gets announced, and you'd like a mention, we'll gladly shout you out!

Please make sure your PR is passing linting and testing before
submitting. Run `make format`, `make lint` and `make test` to check this
locally.

See contribution guidelines for more information on how to write/run
tests, lint, etc:

https://github.com/langchain-ai/langchain/blob/master/.github/CONTRIBUTING.md

If you're adding a new integration, please include:
1. a test for the integration, preferably unit tests that do not rely on
network access,
2. an example notebook showing its use. It lives in `docs/extras`
directory.

If no one reviews your PR within a few days, please @-mention one of
@baskaryan, @eyurtsev, @hwchase17.
 -->

libs/langchain/langchain/agents/agent.py

@@ -145,10 +145,13 @@ class BaseSingleActionAgent(BaseModel):
     def dict(self, **kwargs: Any) -> Dict:
         """Return dictionary representation of agent."""
         _dict = super().dict()
+        try:
             _type = self._agent_type
+        except NotImplementedError:
+            _type = None
         if isinstance(_type, AgentType):
             _dict["_type"] = str(_type.value)
-        else:
+        elif _type is not None:
             _dict["_type"] = _type
         return _dict
 
@@ -175,6 +178,8 @@ class BaseSingleActionAgent(BaseModel):
 
         # Fetch dictionary to save
         agent_dict = self.dict()
+        if "_type" not in agent_dict:
+            raise NotImplementedError(f"Agent {self} does not support saving")
 
         if save_path.suffix == ".json":
             with open(file_path, "w") as f:

libs/langchain/langchain/chains/base.py

@@ -611,7 +611,10 @@ class Chain(RunnableSerializable[Dict[str, Any], Dict[str, Any]], ABC):
         if self.memory is not None:
             raise ValueError("Saving of memory is not yet supported.")
         _dict = super().dict(**kwargs)
+        try:
             _dict["_type"] = self._chain_type
+        except NotImplementedError:
+            pass
         return _dict
 
     def save(self, file_path: Union[Path, str]) -> None:
@@ -639,6 +642,8 @@ class Chain(RunnableSerializable[Dict[str, Any], Dict[str, Any]], ABC):
 
         # Fetch dictionary to save
         chain_dict = self.dict()
+        if "_type" not in chain_dict:
+            raise NotImplementedError(f"Chain {self} does not support saving.")
 
         if save_path.suffix == ".json":
             with open(file_path, "w") as f:

libs/langchain/langchain/load/serializable.py

@@ -31,6 +31,13 @@ class SerializedNotImplemented(BaseSerialized):
     repr: Optional[str]
 
 
+def try_neq_default(value: Any, key: str, model: BaseModel) -> bool:
+    try:
+        return model.__fields__[key].get_default() != value
+    except Exception:
+        return True
+
+
 class Serializable(BaseModel, ABC):
     """Serializable base class."""
 
@@ -81,7 +88,7 @@ class Serializable(BaseModel, ABC):
         return [
             (k, v)
             for k, v in super().__repr_args__()
-            if (k not in self.__fields__ or self.__fields__[k].get_default() != v)
+            if (k not in self.__fields__ or try_neq_default(v, k, self))
         ]
 
     _lc_kwargs = PrivateAttr(default_factory=dict)

libs/langchain/langchain/schema/runnable/__init__.py

@@ -2,6 +2,7 @@ from langchain.schema.runnable._locals import GetLocalVar, PutLocalVar
 from langchain.schema.runnable.base import (
     Runnable,
     RunnableBinding,
+    RunnableGenerator,
     RunnableLambda,
     RunnableMap,
     RunnableSequence,
@@ -12,8 +13,10 @@ from langchain.schema.runnable.config import RunnableConfig, patch_config
 from langchain.schema.runnable.fallbacks import RunnableWithFallbacks
 from langchain.schema.runnable.passthrough import RunnablePassthrough
 from langchain.schema.runnable.router import RouterInput, RouterRunnable
+from langchain.schema.runnable.utils import ConfigurableField
 
 __all__ = [
+    "ConfigurableField",
     "GetLocalVar",
     "patch_config",
     "PutLocalVar",
@@ -24,6 +27,7 @@ __all__ = [
     "RunnableBinding",
     "RunnableBranch",
     "RunnableConfig",
+    "RunnableGenerator",
     "RunnableLambda",
     "RunnableMap",
     "RunnablePassthrough",

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

@@ -227,7 +227,7 @@ class RunnableConfigurableFields(DynamicRunnable[Input, Output]):
         }
 
         if configurable:
-            return self.default.__class__(**{**self.default.dict(), **configurable})
+            return self.default.__class__(**{**self.default.__dict__, **configurable})
         else:
             return self.default