how to use select widget?

[Fei-Wang]

class InputModel(BaseModel):
    choice: str = Field(
        ...,
        extra={
            "widget": {
                "type": "select",
                "options": ["String1", "String2"],
                # "oneOf": ["String1", "String2"],
                # "options": {"oneOf": ["String1", "String2"]},
            }
        },
    )

chain = prompt.with_types(input_type=InputModel) | llm | StrOutputParser()

I have already tried the three methods mentioned above, all of which failed. I read https://python.langchain.com/docs/langserve#playground-widgets, but I still don't know how to use the select widget.

[eyurtsev]

Hi @Fei-Wang,

The only widgets can be specified in the extras: "chat" and "base64file".

All the other widgets are constructed automatically by the UI depending on the schema of the Runnable.

If you want to do a select, you need to create a configurable runnable -- the widget will be created automatically

See LCEL documentation for configurable runnables: https://python.langchain.com/docs/expression_language/how_to/configure

Here's a server example: https://github.com/langchain-ai/langserve/blob/main/examples/configurable_chain/server.py