If else dropdown

When i receive Dcc.location url and match something
when match my something then show dropdown and graph
but not match something then just show error 404

app = Dash(__name__)

app.layout = html.Div([
    dcc.Location(id='url', refresh=False),
    html.Div(id='page-content'),
])

@app.callback(
    Output('page-content', 'children'),
    Input('url', 'search'),
    Input('dropdown', 'value')
)```

but just one layout and first take a dropdown then must show dropdwon??

Hi @limaa, could you try to explain in a different way? I don’t see any drop-down in your layout.