core[patch]: fix structured prompt template format (#27003)

template_format is an init argument on ChatPromptTemplate but not an
attribute on the object so was getting shoved into
StructuredPrompt.structured_ouptut_kwargs

libs/core/langchain_core/prompts/structured.py

@@ -2,6 +2,7 @@ from collections.abc import Iterator, Mapping, Sequence
 from typing import (
     Any,
     Callable,
+    Literal,
     Optional,
     Union,
 )
@@ -37,6 +38,7 @@ class StructuredPrompt(ChatPromptTemplate):
         schema_: Optional[Union[dict, type[BaseModel]]] = None,
         *,
         structured_output_kwargs: Optional[dict[str, Any]] = None,
+        template_format: Literal["f-string", "mustache", "jinja2"] = "f-string",
         **kwargs: Any,
     ) -> None:
         schema_ = schema_ or kwargs.pop("schema")
@@ -47,6 +49,7 @@ class StructuredPrompt(ChatPromptTemplate):
             messages=messages,
             schema_=schema_,
             structured_output_kwargs=structured_output_kwargs,
+            template_format=template_format,
             **kwargs,
         )
 

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

@@ -1,13 +1,13 @@
 from functools import partial
 from inspect import isclass
 from typing import Any, Union, cast
-from typing import Optional as Optional
 
 from pydantic import BaseModel
 
 from langchain_core.language_models import FakeListChatModel
 from langchain_core.load.dump import dumps
 from langchain_core.load.load import loads
+from langchain_core.messages import HumanMessage
 from langchain_core.prompts.structured import StructuredPrompt
 from langchain_core.runnables.base import Runnable, RunnableLambda
 from langchain_core.utils.pydantic import is_basemodel_subclass
@@ -121,3 +121,14 @@ def test_structured_prompt_kwargs() -> None:
     chain = prompt | model
 
     assert chain.invoke({"hello": "there"}) == OutputSchema(name="yo", value=7)
+
+
+def test_structured_prompt_template_format() -> None:
+    prompt = StructuredPrompt(
+        [("human", "hi {{person.name}}")], schema={}, template_format="mustache"
+    )
+    assert prompt.messages[0].prompt.template_format == "mustache"  # type: ignore[union-attr, union-attr]
+    assert prompt.input_variables == ["person"]
+    assert prompt.invoke({"person": {"name": "foo"}}).to_messages() == [
+        HumanMessage("hi foo")
+    ]

libs/langchain/tests/unit_tests/chat_models/test_base.py

@@ -126,8 +126,6 @@ def test_configurable() -> None:
             "tiktoken_model_name": None,
             "default_headers": None,
             "default_query": None,
-            "http_client": None,
-            "http_async_client": None,
             "stop": None,
             "extra_body": None,
             "include_response_headers": False,