check.required() not working with input_selectize()

[sravanpannala]

I'm trying to use shiny-validate for python for checking if the user has selected exactly 5 choices in input_selectize.
The documentation shows that with the current rules, this is not possible.
Also, check.required() is not working with input_selectize at all. That is, no validation is occurring.
Here is my cod

app_ui = ui.page_fluid(
    ui.input_selectize("players","Lineup (Select Exactly 5 players)",player_dict,multiple=True, width="70%")
)

def server(input, output, session):
    iv = InputValidator()
    iv.add_rule("players",check.required())
    iv.enable()
    
   @render.plot(alt="Stat Trends")
    def plot():
        req(iv.is_valid())
        fig, ax = plt.subplots(1,1
        return fig

The red text isn't showing under input_selectize, and the plot is showing when it shouldn't.

[gshotwell]

You can define your own checks like this (this isn't documented anywhere yet). The rules for check functions are that they must return a function which takes a value argument, and returns a message if the check fails.

from shiny import App, ui, render, req
from shiny_validate import InputValidator, check

app_ui = ui.page_fluid(
    # ui.input_text("letters", "Letters"),
    ui.input_selectize(
        "letters", "Letters", choices=["A", "B", "C", "D", "E"], multiple=True
    ),
    ui.output_text("greeting"),
)


def n_selected(n=5):
    def inner(value):
        if len(value) != 5:
            return f"Please select {n} letters"

    return inner


def server(input, output, session):
    iv = InputValidator()

    iv.add_rule("letters", n_selected())
    iv.enable()

    @render.text
    def greeting():
        req(iv.is_valid())
        return f"Nice to meet you, {input.name()} <{input.email()}>!"


app = App(app_ui, server)