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langfuse-hotswap

API reference

rusih100/langfuse-hotswap

API reference¶

Everything below is importable from langfuse_hotswap.

`LangfuseChainFactory`¶

LangfuseChainFactory(
    client: Langfuse,
    models: Mapping[str, BaseChatModel],
    *,
    allowed_config_keys: Iterable[str] | Literal["any"] | None = None,
    label: str | None = None,
    template_format: Literal["langfuse", "f-string", "mustache", "jinja2"] = "langfuse",
    hooks: Iterable[Callable[..., Runnable]] | None = None,
)

Argument	Meaning
`client`	The Langfuse client, usually `langfuse.get_client()`.
`models`	Name to chat model. The prompt config selects one with `provider`. Must not be empty.
`allowed_config_keys`	Config keys that may override model fields: `None` for none, a set, or `"any"`. A string other than `"any"` raises `TypeError`.
`label`	Prompt label `create` uses when given neither a label nor a version.
`template_format`	Renderer for prompts whose config does not set, or may not set, `template_format`.
`hooks`	Model hooks applied to every chain after its own `with_model` hooks. A single callable instead of a collection raises `TypeError`. See Hooks for every chain.

`create`¶

factory.create(prompt_name: str, *, label: str | None = None, version: int | None = None, **get_prompt_kwargs) -> LangfusePromptRunnable[BaseMessage]

label and version together raise ValueError, so does an empty name. fallback raises TypeError. Every other keyword argument goes to client.get_prompt.

`LangfusePromptRunnable`¶

A Runnable[dict[str, Any], Output]. Input is a dict of prompt variables; Output is BaseMessage unless a hook changes it.

Method	Returns
`invoke`, `ainvoke`, `stream`, `astream`, `batch`, `abatch`, `astream_events`, `transform`, ...	The LangChain `Runnable` interface. `batch` and its variants are the inherited ones.
`with_model(hook)`	A copy whose model is replaced by `hook(model)` on every rebuild. A hook with a `prompt` parameter also receives a copy of the prompt client.
`with_structured_output(schema, **kwargs)`	A copy that parses the output with `model.with_structured_output`.
`bind_tools(tools, **kwargs)`	A copy with the tools bound by `model.bind_tools`.
`get_input_schema()`, `get_output_schema()`	The schema of the current chain, or a permissive one when Langfuse is unreachable. Fetches and builds the chain.
`copy.copy`, `copy.deepcopy`	A copy that shares the client and the hooks and starts with an empty cache.

`LangfusePromptTemplate`¶

A BaseChatPromptTemplate over the messages of a Langfuse prompt. LangfusePromptTemplate.from_prompt(prompt, template_format="langfuse") builds it and attaches the prompt as metadata["langfuse_prompt"]. See Templates.

Errors¶

Class	Raised when
`HotswapError`	Base class of the two below.
`PromptFetchError`	The prompt could not be fetched and there is no built chain. The SDK error is `__cause__`.
`ChainBuildError`	The chain could not be built and there is no previous chain. The original error is `__cause__`.