如果发生情况则生成警报消息，否则显示应用程序

Question

目标：如果发生条件（即 URL 路径名中没有数据），我想弹出一个警报组件 否则渲染应用程序

到目前为止我尝试过的事情

app.layout = dbc.Container([

    dbc.Alert([...], id='alert', is_open=False),
    dbc.Container([rows & columns (all visuals are here)], id='page1')
])

@app.callback(
    [Output('alert', 'is_open'),
     Output('store-component', 'data'),
     Output('page1', 'children')],
    Input('url', 'pathname')
)
def extract_path_from_url(pathname):
    if pathname name contains ... :
       store the dataset in the Store component and **DONT SHOW THE ALERT BUTTON**
    else:
       **SHOW THE ALERT BUTTON** and that's it

    ... other callbacks generating the visuals based on the store-component ...

这不起作用，有没有正确的方法来实现这一目标？

编辑： 最新尝试：

这是我更新的回调和布局。到目前为止，当条件为 True 时，它工作正常，警报组件不会显示，并且一切都显示正常。问题是，当条件为假时，警报消息显示成功，但我们可以看到图表是空的。我想隐藏它们或者根本不渲染它们...

app.layout = dbc.Container([

    dbc.Alert([...], id='alert', is_open=False),
    dbc.Container([rows & columns (all visuals are here)], id='container')
])


@app.callback(
    [Output('alert', 'is_open'),
     Output('store-component', 'data'),
     Output('container', 'style')],
    Input('url', 'pathname')
)
def extract_path_from_url(pathname):
    if pathname name contains ... :
       return dash.no_update, data, dash.no_update
    else:
       return True, dash.no_update, {'display': 'none'}

Answer 1

是的，您可以创建它。只需简单地写下条件即可，例如（最高价格交叉 收盘价）。写完这篇文章后，当高价超过单支蜡烛的收盘价时，您将获得完美的警报时间。

Answer 2

Python Plotly-Dash 应用程序中

dbc

“警告”警报的 URL 条件显示

from dash import Dash, Input, Output
from dash import dcc, html

import dash_bootstrap_components as dbc

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

# Sample layout
app.layout = dbc.Container(
    [
        dcc.Location(id="url", refresh=False),
        dbc.Alert(
            [
                html.H3("Warning!"),
                html.Hr(),
                html.P("No data found for this URL."),
            ],
            id="alert",
            is_open=False,
            color="warning",
        ),
        dbc.Container(
            [
                # Mock "rows & columns (all visuals are here)"
                html.H1("Main Content"),
                html.Div(
                    "This is the main content that"
                    " will be hidden or shown based on the URL."
                ),
                dcc.Graph(
                    id="example-graph",
                    figure={
                        "data": [
                            {
                                "x": [1, 2, 3],
                                "y": [4, 1, 2],
                                "type": "bar",
                                "name": "Sample Data",
                            },
                        ],
                        "layout": {"title": "Sample Data Visualization"},
                    },
                ),
            ],
            id="container",
        ),
    ],
    style={"margin": "10%"},
)


@app.callback(
    [Output("alert", "is_open"), Output("container", "style")],
    Input("url", "pathname"),
)
def extract_path_from_url(pathname):

    # For demonstration, if pathname contains "nodata", assume no data is found
    if "nodata" in pathname:
        # Show the alert and hide the main content
        return True, {"display": "none"}
    else:
        # Hide the alert and show the main content
        return False, {"display": "block"}


if __name__ == "__main__":
    app.run_server(debug=True)

产生：