Validate user input shiny for python

[iain]

Hi,

Would anyone have any tips or suggestions on how to validate a user input in python for shiny?

For example in this app I would like to provide a user friendly message indicating a number is required. Currently the app returns an ugly error message instead.

In R, I would accomplish this using Shiny Validate

Thanks

Iain

[Gordon_Shotwell]

Hi Ian,

Thanks for the reprex, we don't have validation in the python package yet, so what I'd recommend is using reactive ui components and a ui.markdown or ui.HTML error message. This was a popular pattern in R land prior to validate

from shiny import App, reactive, render, ui

app_ui = ui.page_fluid(
    ui.input_text("x", "Type a number"),
    ui.output_ui("txt1")
)


def server(input, output, session):
    @output
    @render.text()
    def x_times_2():
        val = int(input.x()) * 2
        print(f"Running x_times_2(). Result is {val}.")
        return val

    @output
    @render.text
    def txt1():
        if input.x().isnumeric():
            return ui.output_text_verbatim("x_times_2")
        else:
            return ui.markdown("**Please enter a number**")

app = App(app_ui, server)