Can not set the value of Flet dropdown

Question

Can not set the value of the dropdown. I'm using an example from the flet site. The only way of set the value is add some item do the dropdown but But what i need is set the value without any selection item? Thank you!

import flet as ft

def main(page: ft.Page):
    def find_option(option_name):
        for option in d.options:
            if option_name == option.key:
                return option
            return None

    def add_clicked(e):
        d.value = "test"
        page.update()
    
    def delete_clicked(e):
        option = find_option(d.value)
        if option != None:
            d.options.remove(option)
            # d.value = None
            page.update()

d = ft.Dropdown()
option_textbox = ft.TextField(hint_text="Enter item name")
add = ft.ElevatedButton("Add", on_click=add_clicked)
delete = ft.OutlinedButton("Delete selected", on_click=delete_clicked)
page.padding = 50
page.add(d, ft.Row(controls=[option_textbox, add, delete]))

ft.app(target=main)

Answer 1

flet.Dropdown need flet.dropdown.Option in the 'options' list with the same value you want set.

the example is here:

import flet as ft

def main(page: ft.Page):
    def find_option(option_name):
        for option in d.options:
            if option_name == option.key:
                return option
            return None

    def add_clicked(e):
        d.value = "test"
        page.update()
    
    def delete_clicked(e):
        option = find_option(d.value)
        if option != None:
            d.options.remove(option)
            # d.value = None
            page.update()

    d = ft.Dropdown(options=[ft.dropdown.Option("test")]) # simple change
    option_textbox = ft.TextField(hint_text="Enter item name")
    add = ft.ElevatedButton("Add", on_click=add_clicked)
    delete = ft.OutlinedButton("Delete selected", on_click=delete_clicked)
    page.padding = 50
    page.add(d, ft.Row(controls=[option_textbox, add, delete]))

ft.app(target=main)