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pydantic_ai.models.function

A model controlled by a local function.

FunctionModel is similar to TestModel, but allows greater control over the model's behavior.

It's primary use case for more advanced unit testing than is possible with TestModel.

FunctionModel dataclass

Bases: Model

A model controlled by a local function.

Apart from __init__, all methods are private or match those of the base class.

__init__ 

__init__(function: FunctionDef) -> None

__init__(*, stream_function: StreamFunctionDef) -> None

__init__(
    function: FunctionDef,
    *,
    stream_function: StreamFunctionDef
) -> None

__init__(
    function: FunctionDef | None = None,
    *,
    stream_function: StreamFunctionDef | None = None
)

Initialize a FunctionModel.

Either function or stream_function must be provided, providing both is allowed.

Parameters:

Name Type Description Default
function FunctionDef | None

The function to call for non-streamed requests.

 None
stream_function StreamFunctionDef | None

The function to call for streamed requests.

 None

AgentInfo dataclass

Information about an agent.

This is passed as the second to functions.

retrievers instance-attribute 

retrievers: Mapping[str, AbstractToolDefinition]

The retrievers available on this agent.

allow_text_result instance-attribute 

allow_text_result: bool

Whether a plain text result is allowed.

result_tools instance-attribute 

result_tools: list[AbstractToolDefinition] | None

The tools that can called as the final result of the run.

DeltaToolCall dataclass

Incremental change to a tool call.

Used to describe a chunk when streaming structured responses.

name class-attribute instance-attribute 

name: str | None = None

Incremental change to the name of the tool.

json_args class-attribute instance-attribute 

json_args: str | None = None

Incremental change to the arguments as JSON

DeltaToolCalls module-attribute 

DeltaToolCalls: TypeAlias = dict[int, DeltaToolCall]

A mapping of tool call IDs to incremental changes.

FunctionDef module-attribute 

FunctionDef: TypeAlias = Callable[
    [list[Message], AgentInfo], ModelAnyResponse
]

A function used to generate a non-streamed response.

StreamFunctionDef module-attribute 

StreamFunctionDef: TypeAlias = Callable[
    [list[Message], AgentInfo],
    Union[Iterable[str], Iterable[DeltaToolCalls]],
]

A function used to generate a streamed response.

FunctionAgentModel dataclass

Bases: AgentModel

Implementation of AgentModel for FunctionModel.

FunctionStreamTextResponse dataclass

Bases: StreamTextResponse

Implementation of StreamTextResponse for FunctionModel.

FunctionStreamStructuredResponse dataclass

Bases: StreamStructuredResponse

Implementation of StreamStructuredResponse for FunctionModel.