Plotly-Dash：隐藏和取消隐藏下拉菜单

Question

我想用我的下拉菜单隐藏启动我的 Dash，然后在另一个下拉菜单上选择某些内容后取消隐藏我的第一个下拉菜单。如果您有任何想法，我想知道，也许这是我的小脚本上的一个错误。

这是一个小例子：

import dash
from dash.dependencies import Input, Output
import dash_core_components as dcc
import dash_html_components as html

app = dash.Dash('example')

app.layout = html.Div([
    dcc.Dropdown(
        id = 'dropdown-to-show_or_hide-element',
        options=[
            {'label': 'Show element', 'value': 'on'},
            {'label': 'Hide element', 'value': 'off'}
        ],
        value = 'off'
    ),

    # Create Div to place a conditionally visible element inside
    html.Div([
        # Create element to hide/show, in this case an 'Input Component'
        dcc.Input(
        id = 'element-to-hide',
        placeholder = 'something',
        value = 'Can you see me?',
        )
    ], style= {'display': 'none'} # <-- This is the line that will be changed by the dropdown callback
    )
    ])

@app.callback(
   Output(component_id='element-to-hide', component_property='style'),
   [Input(component_id='dropdown-to-show_or_hide-element', component_property='value')])

def show_hide_element(visibility_state):
    if visibility_state == 'on':
        return {'display': 'block'}
    if visibility_state == 'off':
        return {'display': 'none'}

if __name__ == '__main__':
    app.server.run(debug=False, threaded=True)

Answer 1

通过稍微更改您的代码（我更改了您的函数采用的参数并在 if 语句中使用相同的参数，此代码似乎可以工作）。我还将原始样式更改为block，它允许元素存在，但仅在show 下拉列表中显示。

import dash
from dash.dependencies import Input, Output
import dash_core_components as dcc
import dash_html_components as html

app = dash.Dash('example')

app.layout = html.Div([
    dcc.Dropdown(
        id = 'dropdown-to-show_or_hide-element',
        options=[
            {'label': 'Show element', 'value': 'on'},
            {'label': 'Hide element', 'value': 'off'}
        ],
        value = 'off'
    ),

    # Create Div to place a conditionally visible element inside
    html.Div([
        # Create element to hide/show, in this case an 'Input Component'
        dcc.Input(
        id = 'element-to-hide',
        placeholder = 'something',
        value = 'Can you see me?',
        )
    ], style= {'display': 'block'} # <-- This is the line that will be changed by the dropdown callback
    )
    ])

@app.callback(
   Output(component_id='element-to-hide', component_property='style'),
   [Input(component_id='dropdown-to-show_or_hide-element', component_property='value')])

def show_hide_element(value):
    if value == 'on':
        return {'display': 'block'}
    if value == 'off':
        return {'display': 'none'}

if __name__ == '__main__':
    app.server.run(debug=False)