每次经过新日期时如何更新数据框

Question

我正在构建一个仪表板，该仪表板根据输入的日期生成报告。报告中生成了5个csv，并以下拉方式显示并可供下载。问题在于，一旦生成新报告，正在读取csv的数据帧就不会更新。它仍然保存上一次运行的数据。我该如何解决？

from kontekst_report_server_datewise import kontekst


def generate_table(dataframe,max_rows=10):
    return html.Table(
        # Header
        [html.Tr([html.Th(col) for col in dataframe.columns])] +

        # Body
        [html.Tr([
            html.Td(dataframe.iloc[i][col]) for col in dataframe.columns
        ]) for i in range(min(len(dataframe), max_rows))]
    )


external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']
# external_stylesheets = ['https://maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css']


app = dash.Dash(__name__, external_stylesheets=external_stylesheets)

app.layout = html.Div([
    dcc.DatePickerRange(id='date-picker-range',
                                         start_date=datetime(2019, 4, 3), end_date=datetime(2019, 4, 4)),
    dcc.Dropdown(
        id='my-dropdown',
        options=[
            {'label' : 'Returns Summary' , 'value' : 'df1'},
            {'label' : 'Return Guide Doc Details' , 'value' : 'df2'},
            {'label' : 'Return Guide id Counts' , 'value' : 'df3'},
            {'label' : 'Non Return Guide id Counts', 'value' : 'df4'},
            {'label' : 'Order Creation Details' , 'value' : 'df5'}
        ],
        # value='df1'
        # multi = True
    ),
    html.Div(id='output-container'),
    html.A('Download CSV', id = 'my-link'),
    html.Div(id='kontekst')
])


@app.callback(
    dash.dependencies.Output('output-container', 'children'),
    [dash.dependencies.Input('my-dropdown', 'value')])
def update_output(value):
    df1 = pd.read_csv('returns_summary.csv')
    df2 = pd.read_csv('ReturnGuideDocDetails.csv')
    df3 = pd.read_csv('Return_guideid_counts.csv')
    df4 = pd.read_csv('NonReturn_guideid_counts.csv')
    df5 = pd.read_csv('OrderCreationdetails.csv')

    if value == 'df1':
        return generate_table(df1)
    elif value == 'df2':
        return generate_table(df2)
    elif value == 'df3' :
        return generate_table(df3)
    elif value == 'df4' :
        return generate_table(df4)
    elif value == 'df5' :
        return generate_table(df5)


@app.callback(Output('my-link', 'href'), [Input('my-dropdown', 'value')])
def update_link(value):
    return '/dash/urlToDownload?value={}'.format(value)



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