_create_subset_model_v2() — langchain Function Reference

Architecture documentation for the _create_subset_model_v2() function in pydantic.py from the langchain codebase.

Function python Observability TelemetryUtilities calls 1 called by 2

Entity Profile

Observability→ TelemetryUtilities→ _create_subset_model_v2() — langchain Function Reference

Dependency Diagram

graph TD
  9e5cf970_9661_1d7f_abe9_9d3a2271e33c["_create_subset_model_v2()"]
  892b1d9f_bb87_0364_19af_71382204e430["pydantic.py"]
  9e5cf970_9661_1d7f_abe9_9d3a2271e33c -->|defined in| 892b1d9f_bb87_0364_19af_71382204e430
  9e5cf970_9661_1d7f_abe9_9d3a2271e33c["_create_subset_model_v2()"]
  9e5cf970_9661_1d7f_abe9_9d3a2271e33c -->|calls| 9e5cf970_9661_1d7f_abe9_9d3a2271e33c
  b0860ec1_de71_8597_62af_8ca59b0ea27b["_create_subset_model()"]
  b0860ec1_de71_8597_62af_8ca59b0ea27b -->|calls| 9e5cf970_9661_1d7f_abe9_9d3a2271e33c
  9e5cf970_9661_1d7f_abe9_9d3a2271e33c["_create_subset_model_v2()"]
  9e5cf970_9661_1d7f_abe9_9d3a2271e33c -->|calls| 9e5cf970_9661_1d7f_abe9_9d3a2271e33c
  style 9e5cf970_9661_1d7f_abe9_9d3a2271e33c fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/utils/pydantic.py lines 231–269

def _create_subset_model_v2(
    name: str,
    model: type[BaseModel],
    field_names: list[str],
    *,
    descriptions: dict | None = None,
    fn_description: str | None = None,
) -> type[BaseModel]:
    """Create a Pydantic model with a subset of the model fields."""
    descriptions_ = descriptions or {}
    fields = {}
    for field_name in field_names:
        field = model.model_fields[field_name]
        description = descriptions_.get(field_name, field.description)
        field_info = FieldInfoV2(description=description, default=field.default)
        if field.metadata:
            field_info.metadata = field.metadata
        fields[field_name] = (field.annotation, field_info)

    rtn = cast(
        "type[BaseModel]",
        _create_model_base(  # type: ignore[call-overload]
            name, **fields, __config__=ConfigDict(arbitrary_types_allowed=True)
        ),
    )

    # TODO(0.3): Determine if there is a more "pydantic" way to preserve annotations.
    # This is done to preserve __annotations__ when working with pydantic 2.x
    # and using the Annotated type with TypedDict.
    # Comment out the following line, to trigger the relevant test case.
    selected_annotations = [
        (name, annotation)
        for name, annotation in model.__annotations__.items()
        if name in field_names
    ]

    rtn.__annotations__ = dict(selected_annotations)
    rtn.__doc__ = textwrap.dedent(fn_description or model.__doc__ or "")
    return rtn