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 = {

libs/core/tests/unit_tests/prompts/test_chat.py

@@ -28,7 +28,8 @@ from langchain_core.prompts.chat import (
 )
 
 
-def create_messages() -> List[BaseMessagePromptTemplate]:
+@pytest.fixture
+def messages() -> List[BaseMessagePromptTemplate]:
     """Create messages."""
     system_message_prompt = SystemMessagePromptTemplate(
         prompt=PromptTemplate(
@@ -63,11 +64,14 @@ def create_messages() -> List[BaseMessagePromptTemplate]:
     ]
 
 
-def create_chat_prompt_template() -> ChatPromptTemplate:
+@pytest.fixture
+def chat_prompt_template(
+    messages: List[BaseMessagePromptTemplate],
+) -> ChatPromptTemplate:
     """Create a chat prompt template."""
     return ChatPromptTemplate(
         input_variables=["foo", "bar", "context"],
-        messages=create_messages(),  # type: ignore[arg-type]
+        messages=messages,  # type: ignore[arg-type]
     )
 
 
@@ -110,10 +114,9 @@ def test_message_prompt_template_from_template_file() -> None:
     assert expected == actual
 
 
-def test_chat_prompt_template() -> None:
+async def test_chat_prompt_template(chat_prompt_template: ChatPromptTemplate) -> None:
     """Test chat prompt template."""
-    prompt_template = create_chat_prompt_template()
-    prompt = prompt_template.format_prompt(foo="foo", bar="bar", context="context")
+    prompt = chat_prompt_template.format_prompt(foo="foo", bar="bar", context="context")
     assert isinstance(prompt, ChatPromptValue)
     messages = prompt.to_messages()
     assert len(messages) == 4
@@ -122,6 +125,12 @@ def test_chat_prompt_template() -> None:
     assert messages[2].content == "I'm an AI. I'm foo. I'm bar."
     assert messages[3].content == "I'm a generic message. I'm foo. I'm bar."
 
+    async_prompt = await chat_prompt_template.aformat_prompt(
+        foo="foo", bar="bar", context="context"
+    )
+
+    assert async_prompt.to_messages() == messages
+
     string = prompt.to_string()
     expected = (
         "System: Here's some context: context\n"
@@ -131,13 +140,15 @@ def test_chat_prompt_template() -> None:
     )
     assert string == expected
 
-    string = prompt_template.format(foo="foo", bar="bar", context="context")
+    string = chat_prompt_template.format(foo="foo", bar="bar", context="context")
     assert string == expected
 
 
-def test_chat_prompt_template_from_messages() -> None:
+def test_chat_prompt_template_from_messages(
+    messages: List[BaseMessagePromptTemplate],
+) -> None:
     """Test creating a chat prompt template from messages."""
-    chat_prompt_template = ChatPromptTemplate.from_messages(create_messages())
+    chat_prompt_template = ChatPromptTemplate.from_messages(messages)
     assert sorted(chat_prompt_template.input_variables) == sorted(
         ["context", "foo", "bar"]
     )
@@ -171,11 +182,12 @@ def test_chat_prompt_template_from_messages_using_role_strings() -> None:
     ]
 
 
-def test_chat_prompt_template_with_messages() -> None:
-    messages: List[Union[BaseMessagePromptTemplate, BaseMessage]] = (
-        create_messages() + [HumanMessage(content="foo")]
+def test_chat_prompt_template_with_messages(
+    messages: List[BaseMessagePromptTemplate],
+) -> None:
+    chat_prompt_template = ChatPromptTemplate.from_messages(
+        messages + [HumanMessage(content="foo")]
     )
-    chat_prompt_template = ChatPromptTemplate.from_messages(messages)
     assert sorted(chat_prompt_template.input_variables) == sorted(
         ["context", "foo", "bar"]
     )

libs/core/tests/unit_tests/prompts/test_pipeline_prompt.py

@@ -32,7 +32,7 @@ def test_multi_variable_pipeline() -> None:
     assert output == "okay jim deep"
 
 
-def test_partial_with_chat_prompts() -> None:
+async def test_partial_with_chat_prompts() -> None:
     prompt_a = ChatPromptTemplate(
         input_variables=["foo"], messages=[MessagesPlaceholder(variable_name="foo")]
     )
@@ -43,3 +43,5 @@ def test_partial_with_chat_prompts() -> None:
     assert pipeline_prompt.input_variables == ["bar"]
     output = pipeline_prompt.format_prompt(bar="okay")
     assert output.to_messages()[0].content == "jim okay"
+    output = await pipeline_prompt.aformat_prompt(bar="okay")
+    assert output.to_messages()[0].content == "jim okay"

libs/core/tests/unit_tests/prompts/test_prompt.py

@@ -351,3 +351,22 @@ def test_prompt_invoke_with_metadata() -> None:
     assert len(tracer.traced_runs) == 1
     assert tracer.traced_runs[0].extra["metadata"] == {"version": "1", "foo": "bar"}  # type: ignore
     assert tracer.traced_runs[0].tags == ["tag1", "tag2"]  # type: ignore
+
+
+async def test_prompt_ainvoke_with_metadata() -> None:
+    """Test prompt can be invoked with metadata."""
+    template = "This is a {foo} test."
+    prompt = PromptTemplate(
+        input_variables=["foo"],
+        template=template,
+        metadata={"version": "1"},
+        tags=["tag1", "tag2"],
+    )
+    tracer = RunCollectorCallbackHandler()
+    result = await prompt.ainvoke(
+        {"foo": "bar"}, {"metadata": {"foo": "bar"}, "callbacks": [tracer]}
+    )
+    assert result.to_string() == "This is a bar test."
+    assert len(tracer.traced_runs) == 1
+    assert tracer.traced_runs[0].extra["metadata"] == {"version": "1", "foo": "bar"}  # type: ignore
+    assert tracer.traced_runs[0].tags == ["tag1", "tag2"]  # type: ignore