add prompt type (#730)

langchain/prompts/base.py

@@ -135,6 +135,17 @@ class BasePromptTemplate(BaseModel, ABC):
             prompt.format(variable1="foo")
         """
 
+    @property
+    @abstractmethod
+    def _prompt_type(self) -> str:
+        """Return the prompt type key."""
+
+    def dict(self, **kwargs: Any) -> Dict:
+        """Return dictionary representation of prompt."""
+        prompt_dict = super().dict()
+        prompt_dict["_type"] = self._prompt_type
+        return prompt_dict
+
     def save(self, file_path: Union[Path, str]) -> None:
         """Save the prompt.
 

langchain/prompts/few_shot.py

@@ -109,11 +109,13 @@ class FewShotPromptTemplate(BasePromptTemplate, BaseModel):
         # Format the template with the input variables.
         return DEFAULT_FORMATTER_MAPPING[self.template_format](template, **kwargs)
 
+    @property
+    def _prompt_type(self) -> str:
+        """Return the prompt type key."""
+        return "few_shot"
+
     def dict(self, **kwargs: Any) -> Dict:
         """Return a dictionary of the prompt."""
         if self.example_selector:
             raise ValueError("Saving an example selector is not currently supported")
-
-        prompt_dict = super().dict()
-        prompt_dict["_type"] = "few_shot"
-        return prompt_dict
+        return super().dict(**kwargs)

langchain/prompts/loading.py

@@ -83,7 +83,7 @@ def _load_few_shot_prompt(config: dict) -> FewShotPromptTemplate:
             )
         config["example_prompt"] = load_prompt(config.pop("example_prompt_path"))
     else:
-        config["example_prompt"] = _load_prompt(config["example_prompt"])
+        config["example_prompt"] = load_prompt_from_config(config["example_prompt"])
     # Load the examples.
     config = _load_examples(config)
     return FewShotPromptTemplate(**config)

langchain/prompts/prompt.py

@@ -31,6 +31,11 @@ class PromptTemplate(BasePromptTemplate, BaseModel):
     template_format: str = "f-string"
     """The format of the prompt template. Options are: 'f-string', 'jinja2'."""
 
+    @property
+    def _prompt_type(self) -> str:
+        """Return the prompt type key."""
+        return "prompt"
+
     class Config:
         """Configuration for this pydantic object."""