Ensure dict() does not raise not implemented error, which should instead be raised in our custom method save() (#11970)

.dict() is a Pydantic method that cannot raise exceptions, as it is used
eg. in `__eq__`

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libs/langchain/langchain/agents/agent.py

@@ -274,7 +274,10 @@ class BaseMultiActionAgent(BaseModel):
     def dict(self, **kwargs: Any) -> Dict:
         """Return dictionary representation of agent."""
         _dict = super().dict()
-        _dict["_type"] = str(self._agent_type)
+        try:
+            _dict["_type"] = str(self._agent_type)
+        except NotImplementedError:
+            pass
         return _dict
 
     def save(self, file_path: Union[Path, str]) -> None:
@@ -295,11 +298,13 @@ class BaseMultiActionAgent(BaseModel):
         else:
             save_path = file_path
 
-        directory_path = save_path.parent
-        directory_path.mkdir(parents=True, exist_ok=True)
-
         # Fetch dictionary to save
         agent_dict = self.dict()
+        if "_type" not in agent_dict:
+            raise NotImplementedError(f"Agent {self} does not support saving.")
+
+        directory_path = save_path.parent
+        directory_path.mkdir(parents=True, exist_ok=True)
 
         if save_path.suffix == ".json":
             with open(file_path, "w") as f:

libs/langchain/langchain/chains/base.py

@@ -610,8 +610,6 @@ class Chain(RunnableSerializable[Dict[str, Any], Dict[str, Any]], ABC):
                 chain.dict(exclude_unset=True)
                 # -> {"_type": "foo", "verbose": False, ...}
         """
-        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
@@ -633,6 +631,14 @@ class Chain(RunnableSerializable[Dict[str, Any], Dict[str, Any]], ABC):
 
                 chain.save(file_path="path/chain.yaml")
         """
+        if self.memory is not None:
+            raise ValueError("Saving of memory is not yet supported.")
+
+        # Fetch dictionary to save
+        chain_dict = self.dict()
+        if "_type" not in chain_dict:
+            raise NotImplementedError(f"Chain {self} does not support saving.")
+
         # Convert file to Path object.
         if isinstance(file_path, str):
             save_path = Path(file_path)
@@ -642,11 +648,6 @@ class Chain(RunnableSerializable[Dict[str, Any], Dict[str, Any]], ABC):
         directory_path = save_path.parent
         directory_path.mkdir(parents=True, exist_ok=True)
 
-        # 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:
                 json.dump(chain_dict, f, indent=4)

libs/langchain/langchain/prompts/few_shot.py

@@ -1,6 +1,7 @@
 """Prompt template that contains few shot examples."""
 from __future__ import annotations
 
+from pathlib import Path
 from typing import Any, Dict, List, Optional, Union
 
 from langchain.prompts.base import (
@@ -151,11 +152,10 @@ class FewShotPromptTemplate(_FewShotPromptTemplateMixin, StringPromptTemplate):
         """Return the prompt type key."""
         return "few_shot"
 
-    def dict(self, **kwargs: Any) -> Dict:
-        """Return a dictionary of the prompt."""
+    def save(self, file_path: Union[Path, str]) -> None:
         if self.example_selector:
             raise ValueError("Saving an example selector is not currently supported")
-        return super().dict(**kwargs)
+        return super().save(file_path)
 
 
 class FewShotChatMessagePromptTemplate(

libs/langchain/langchain/prompts/few_shot_with_templates.py

@@ -1,5 +1,6 @@
 """Prompt template that contains few shot examples."""
-from typing import Any, Dict, List, Optional
+from pathlib import Path
+from typing import Any, Dict, List, Optional, Union
 
 from langchain.prompts.base import DEFAULT_FORMATTER_MAPPING, StringPromptTemplate
 from langchain.prompts.example_selector.base import BaseExampleSelector
@@ -140,8 +141,7 @@ class FewShotPromptWithTemplates(StringPromptTemplate):
         """Return the prompt type key."""
         return "few_shot_with_templates"
 
-    def dict(self, **kwargs: Any) -> Dict:
-        """Return a dictionary of the prompt."""
+    def save(self, file_path: Union[Path, str]) -> None:
         if self.example_selector:
             raise ValueError("Saving an example selector is not currently supported")
-        return super().dict(**kwargs)
+        return super().save(file_path)

libs/langchain/langchain/schema/output_parser.py

@@ -298,7 +298,10 @@ class BaseOutputParser(
     def dict(self, **kwargs: Any) -> Dict:
         """Return dictionary representation of output parser."""
         output_parser_dict = super().dict(**kwargs)
-        output_parser_dict["_type"] = self._type
+        try:
+            output_parser_dict["_type"] = self._type
+        except NotImplementedError:
+            pass
         return output_parser_dict
 
 

libs/langchain/langchain/schema/prompt_template.py

@@ -132,7 +132,10 @@ class BasePromptTemplate(RunnableSerializable[Dict, PromptValue], ABC):
     def dict(self, **kwargs: Any) -> Dict:
         """Return dictionary representation of prompt."""
         prompt_dict = super().dict(**kwargs)
-        prompt_dict["_type"] = self._prompt_type
+        try:
+            prompt_dict["_type"] = self._prompt_type
+        except NotImplementedError:
+            pass
         return prompt_dict
 
     def save(self, file_path: Union[Path, str]) -> None:
@@ -148,6 +151,12 @@ class BasePromptTemplate(RunnableSerializable[Dict, PromptValue], ABC):
         """
         if self.partial_variables:
             raise ValueError("Cannot save prompt with partial variables.")
+
+        # Fetch dictionary to save
+        prompt_dict = self.dict()
+        if "_type" not in prompt_dict:
+            raise NotImplementedError(f"Prompt {self} does not support saving.")
+
         # Convert file to Path object.
         if isinstance(file_path, str):
             save_path = Path(file_path)
@@ -157,9 +166,6 @@ class BasePromptTemplate(RunnableSerializable[Dict, PromptValue], ABC):
         directory_path = save_path.parent
         directory_path.mkdir(parents=True, exist_ok=True)
 
-        # Fetch dictionary to save
-        prompt_dict = self.dict()
-
         if save_path.suffix == ".json":
             with open(file_path, "w") as f:
                 json.dump(prompt_dict, f, indent=4)