core[minor]: Add aformat to FewShotPromptTemplate (#19652)

libs/core/langchain_core/prompts/base.py

@@ -182,6 +182,23 @@ class BasePromptTemplate(
             prompt.format(variable1="foo")
         """
 
+    async def aformat(self, **kwargs: Any) -> FormatOutputType:
+        """Format the prompt with the inputs.
+
+        Args:
+            kwargs: Any arguments to be passed to the prompt template.
+
+        Returns:
+            A formatted string.
+
+        Example:
+
+        .. code-block:: python
+
+            await prompt.aformat(variable1="foo")
+        """
+        return self.format(**kwargs)
+
     @property
     def _prompt_type(self) -> str:
         """Return the prompt type key."""

libs/core/langchain_core/prompts/few_shot.py

@@ -147,20 +147,6 @@ class FewShotPromptTemplate(_FewShotPromptTemplateMixin, StringPromptTemplate):
         arbitrary_types_allowed = True
 
     def format(self, **kwargs: Any) -> str:
-        """Format the prompt with the inputs.
-
-        Args:
-            **kwargs: Any arguments to be passed to the prompt template.
-
-        Returns:
-            A formatted string.
-
-        Example:
-
-        .. code-block:: python
-
-            prompt.format(variable1="foo")
-        """
         kwargs = self._merge_partial_and_user_variables(**kwargs)
         # Get the examples to use.
         examples = self._get_examples(**kwargs)
@@ -178,6 +164,24 @@ class FewShotPromptTemplate(_FewShotPromptTemplateMixin, StringPromptTemplate):
         # Format the template with the input variables.
         return DEFAULT_FORMATTER_MAPPING[self.template_format](template, **kwargs)
 
+    async def aformat(self, **kwargs: Any) -> str:
+        kwargs = self._merge_partial_and_user_variables(**kwargs)
+        # Get the examples to use.
+        examples = await self._aget_examples(**kwargs)
+        examples = [
+            {k: e[k] for k in self.example_prompt.input_variables} for e in examples
+        ]
+        # Format the examples.
+        example_strings = [
+            await self.example_prompt.aformat(**example) for example in examples
+        ]
+        # Create the overall template.
+        pieces = [self.prefix, *example_strings, self.suffix]
+        template = self.example_separator.join([piece for piece in pieces if piece])
+
+        # 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."""
@@ -383,5 +387,9 @@ class FewShotChatMessagePromptTemplate(
         messages = self.format_messages(**kwargs)
         return get_buffer_string(messages)
 
+    async def aformat(self, **kwargs: Any) -> str:
+        messages = await self.aformat_messages(**kwargs)
+        return get_buffer_string(messages)
+
     def pretty_repr(self, html: bool = False) -> str:
         raise NotImplementedError()

libs/core/langchain_core/prompts/image.py

@@ -3,6 +3,7 @@ from typing import Any, List
 from langchain_core.prompt_values import ImagePromptValue, ImageURL, PromptValue
 from langchain_core.prompts.base import BasePromptTemplate
 from langchain_core.pydantic_v1 import Field
+from langchain_core.runnables import run_in_executor
 from langchain_core.utils import image as image_utils
 
 
@@ -80,5 +81,8 @@ class ImagePromptTemplate(BasePromptTemplate[ImageURL]):
             output["detail"] = detail  # type: ignore[typeddict-item]
         return output
 
+    async def aformat(self, **kwargs: Any) -> ImageURL:
+        return await run_in_executor(None, self.format, **kwargs)
+
     def pretty_repr(self, html: bool = False) -> str:
         raise NotImplementedError()

libs/core/langchain_core/prompts/prompt.py

@@ -114,20 +114,6 @@ class PromptTemplate(StringPromptTemplate):
         return "prompt"
 
     def format(self, **kwargs: Any) -> str:
-        """Format the prompt with the inputs.
-
-        Args:
-            kwargs: Any arguments to be passed to the prompt template.
-
-        Returns:
-            A formatted string.
-
-        Example:
-
-            .. code-block:: python
-
-                prompt.format(variable1="foo")
-        """
         kwargs = self._merge_partial_and_user_variables(**kwargs)
         return DEFAULT_FORMATTER_MAPPING[self.template_format](self.template, **kwargs)
 

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

@@ -96,7 +96,7 @@ def test_prompt_missing_input_variables() -> None:
     ).input_variables == ["foo"]
 
 
-def test_few_shot_functionality() -> None:
+async def test_few_shot_functionality() -> None:
     """Test that few shot works with examples."""
     prefix = "This is a test about {content}."
     suffix = "Now you try to talk about {new_content}."
@@ -112,13 +112,15 @@ def test_few_shot_functionality() -> None:
         example_prompt=EXAMPLE_PROMPT,
         example_separator="\n",
     )
-    output = prompt.format(content="animals", new_content="party")
     expected_output = (
         "This is a test about animals.\n"
         "foo: bar\n"
         "baz: foo\n"
         "Now you try to talk about party."
     )
+    output = prompt.format(content="animals", new_content="party")
+    assert output == expected_output
+    output = await prompt.aformat(content="animals", new_content="party")
     assert output == expected_output
 
 
@@ -365,6 +367,24 @@ class AsIsSelector(BaseExampleSelector):
         return list(self.examples)
 
 
+def test_few_shot_prompt_template_with_selector() -> None:
+    """Tests for few shot chat message template with an example selector."""
+    examples = [
+        {"question": "foo", "answer": "bar"},
+        {"question": "baz", "answer": "foo"},
+    ]
+    example_selector = AsIsSelector(examples)
+
+    few_shot_prompt = FewShotPromptTemplate(
+        input_variables=["foo"],
+        suffix="This is a {foo} test.",
+        example_prompt=EXAMPLE_PROMPT,
+        example_selector=example_selector,
+    )
+    messages = few_shot_prompt.format(foo="bar")
+    assert messages == "foo: bar\n\nbaz: foo\n\nThis is a bar test."
+
+
 def test_few_shot_chat_message_prompt_template_with_selector() -> None:
     """Tests for few shot chat message template with an example selector."""
     examples = [
@@ -421,6 +441,24 @@ class AsyncAsIsSelector(BaseExampleSelector):
         return list(self.examples)
 
 
+async def test_few_shot_prompt_template_with_selector_async() -> None:
+    """Tests for few shot chat message template with an example selector."""
+    examples = [
+        {"question": "foo", "answer": "bar"},
+        {"question": "baz", "answer": "foo"},
+    ]
+    example_selector = AsyncAsIsSelector(examples)
+
+    few_shot_prompt = FewShotPromptTemplate(
+        input_variables=["foo"],
+        suffix="This is a {foo} test.",
+        example_prompt=EXAMPLE_PROMPT,
+        example_selector=example_selector,
+    )
+    messages = await few_shot_prompt.aformat(foo="bar")
+    assert messages == "foo: bar\n\nbaz: foo\n\nThis is a bar test."
+
+
 async def test_few_shot_chat_message_prompt_template_with_selector_async() -> None:
     """Tests for few shot chat message template with an async example selector."""
     examples = [