Multi Dropdown with a Select All button

dropdown_with_select_all.py

from dash import Dash, dcc, html, Input, Output
import dash_bootstrap_components as dbc

app = Dash(__name__, external_stylesheets=[dbc.themes.SPACELAB])

options = ["apples", "oranges", "bananas", "chocolate"]

app.layout = dbc.InputGroup(
    [
        dcc.Dropdown(options, multi=True, id="fruit", style={"width":400}),
        dbc.Button("Select All", id="all"),
    ]
)

@app.callback(
    Output("fruit", "value"),
    Input("all", "n_clicks"),
    prevent_initial_call=True
)
def select_all(_):
    return options

if __name__ == "__main__":
    app.run()