core[minor]: Implement aformat_prompt and ainvoke in BasePromptTemplate (#20035)

libs/core/langchain_core/prompts/base.py

@@ -87,7 +87,7 @@ class BasePromptTemplate(
             **{k: (self.input_types.get(k, str), None) for k in self.input_variables},
         )
 
-    def _format_prompt_with_error_handling(self, inner_input: Dict) -> PromptValue:
+    def _validate_input(self, inner_input: Dict) -> Dict:
         if not isinstance(inner_input, dict):
             if len(self.input_variables) == 1:
                 var_name = self.input_variables[0]
@@ -105,7 +105,17 @@ class BasePromptTemplate(
                 f" Expected: {self.input_variables}"
                 f" Received: {list(inner_input.keys())}"
             )
-        return self.format_prompt(**inner_input)
+        return inner_input
+
+    def _format_prompt_with_error_handling(self, inner_input: Dict) -> PromptValue:
+        _inner_input = self._validate_input(inner_input)
+        return self.format_prompt(**_inner_input)
+
+    async def _aformat_prompt_with_error_handling(
+        self, inner_input: Dict
+    ) -> PromptValue:
+        _inner_input = self._validate_input(inner_input)
+        return await self.aformat_prompt(**_inner_input)
 
     def invoke(
         self, input: Dict, config: Optional[RunnableConfig] = None
@@ -122,10 +132,29 @@ class BasePromptTemplate(
             run_type="prompt",
         )
 
+    async def ainvoke(
+        self, input: Dict, config: Optional[RunnableConfig] = None, **kwargs: Any
+    ) -> PromptValue:
+        config = ensure_config(config)
+        if self.metadata:
+            config["metadata"].update(self.metadata)
+        if self.tags:
+            config["tags"].extend(self.tags)
+        return await self._acall_with_config(
+            self._aformat_prompt_with_error_handling,
+            input,
+            config,
+            run_type="prompt",
+        )
+
     @abstractmethod
     def format_prompt(self, **kwargs: Any) -> PromptValue:
         """Create Prompt Value."""
 
+    async def aformat_prompt(self, **kwargs: Any) -> PromptValue:
+        """Create Prompt Value."""
+        return self.format_prompt(**kwargs)
+
     @root_validator()
     def validate_variable_names(cls, values: Dict) -> Dict:
         """Validate variable names do not include restricted names."""

libs/core/langchain_core/prompts/chat.py

@@ -609,6 +609,18 @@ class BaseChatPromptTemplate(BasePromptTemplate, ABC):
         """
         return self.format_prompt(**kwargs).to_string()
 
+    async def aformat(self, **kwargs: Any) -> str:
+        """Format the chat template into a string.
+
+        Args:
+            **kwargs: keyword arguments to use for filling in template variables
+                      in all the template messages in this chat template.
+
+        Returns:
+            formatted string
+        """
+        return (await self.aformat_prompt(**kwargs)).to_string()
+
     def format_prompt(self, **kwargs: Any) -> PromptValue:
         """
         Format prompt. Should return a PromptValue.
@@ -621,6 +633,10 @@ class BaseChatPromptTemplate(BasePromptTemplate, ABC):
         messages = self.format_messages(**kwargs)
         return ChatPromptValue(messages=messages)
 
+    async def aformat_prompt(self, **kwargs: Any) -> PromptValue:
+        messages = await self.aformat_messages(**kwargs)
+        return ChatPromptValue(messages=messages)
+
     @abstractmethod
     def format_messages(self, **kwargs: Any) -> List[BaseMessage]:
         """Format kwargs into a list of messages."""

libs/core/langchain_core/prompts/image.py

@@ -37,9 +37,11 @@ class ImagePromptTemplate(BasePromptTemplate[ImageURL]):
         return ["langchain", "prompts", "image"]
 
     def format_prompt(self, **kwargs: Any) -> PromptValue:
-        """Create Chat Messages."""
         return ImagePromptValue(image_url=self.format(**kwargs))
 
+    async def aformat_prompt(self, **kwargs: Any) -> PromptValue:
+        return ImagePromptValue(image_url=await self.aformat(**kwargs))
+
     def format(
         self,
         **kwargs: Any,

libs/core/langchain_core/prompts/pipeline.py

@@ -54,9 +54,22 @@ class PipelinePromptTemplate(BasePromptTemplate):
         _inputs = _get_inputs(kwargs, self.final_prompt.input_variables)
         return self.final_prompt.format_prompt(**_inputs)
 
+    async def aformat_prompt(self, **kwargs: Any) -> PromptValue:
+        for k, prompt in self.pipeline_prompts:
+            _inputs = _get_inputs(kwargs, prompt.input_variables)
+            if isinstance(prompt, BaseChatPromptTemplate):
+                kwargs[k] = await prompt.aformat_messages(**_inputs)
+            else:
+                kwargs[k] = await prompt.aformat(**_inputs)
+        _inputs = _get_inputs(kwargs, self.final_prompt.input_variables)
+        return await self.final_prompt.aformat_prompt(**_inputs)
+
     def format(self, **kwargs: Any) -> str:
         return self.format_prompt(**kwargs).to_string()
 
+    async def aformat(self, **kwargs: Any) -> str:
+        return (await self.aformat_prompt(**kwargs)).to_string()
+
     @property
     def _prompt_type(self) -> str:
         raise ValueError

libs/core/langchain_core/prompts/string.py

@@ -160,9 +160,11 @@ class StringPromptTemplate(BasePromptTemplate, ABC):
         return ["langchain", "prompts", "base"]
 
     def format_prompt(self, **kwargs: Any) -> PromptValue:
-        """Create Chat Messages."""
         return StringPromptValue(text=self.format(**kwargs))
 
+    async def aformat_prompt(self, **kwargs: Any) -> PromptValue:
+        return StringPromptValue(text=await self.aformat(**kwargs))
+
     def pretty_repr(self, html: bool = False) -> str:
         # TODO: handle partials
         dummy_vars = {