Plotly Dash：在 Markdown 文本中显示一个变量

Question

我是 Dash 和 Plotly 生态系统的新手，几天前开始构建基于 Web 的仪表板。

这是一段代码：

import dash
import dash_html_components as html
import dash_core_components as dcc


# initialize the application
app = dash.Dash()

# define the layout of the app
app.layout = html.Div([

# add a date range selector
dcc.DatePickerRange(
    id = 'my-date-picker-range',
    min_date_allowed = dt(2010,1,4),
    max_date_allowed = dt(2020, 12, 31),
    initial_visible_month = dt(2020, 5, 23)
),

html.Div(id = 'output-container-date-picker-range'),

# add some markdown text
dcc.Markdown(f'''
    This report covers the time period spanning {start_date} to {end_date}.
    '''),

])


@app.callback(
    dash.dependencies.Output('output-container-date-picker-range', 'children'),
    [dash.dependencies.Input('my-date-picker-range', 'start_date'),
     dash.dependencies.Input('my-date-picker-range', 'end_date')])

app.run_server(debug = True)

我试图在降价文本中显示 start_date 和 end_date 变量（使用 f string）。不幸的是，我收到以下错误消息：

NameError: name 'start_date' is not defined

是否可以在 Markdown 文本中包含变量输出？谢谢！

Answer 1

您正在使用装饰器 (@app.callback)，但您没有将其附加到要执行的函数。您需要将装饰器附加到负责更新正确 div.

的函数

我认为你最好的选择是坚持 documentation。

这给出了与您想要的相似的结果：

import dash
import dash_html_components as html
import dash_core_components as dcc
from datetime import datetime as dt

# initialize the application
app = dash.Dash()

# define the layout of the app
app.layout = html.Div([

    # add a date range selector
    dcc.DatePickerRange(
        id = 'my-date-picker-range',
        min_date_allowed = dt(2010,1,4),
        max_date_allowed = dt(2020, 12, 31),
        initial_visible_month = dt(2020, 5, 23)
    ),

    html.Div(id = 'output-container-date-picker-range'),
])

@app.callback(
    dash.dependencies.Output('output-container-date-picker-range', 'children'),
    [dash.dependencies.Input('my-date-picker-range', 'start_date'),
     dash.dependencies.Input('my-date-picker-range', 'end_date')])
def update_output_div(start_date, end_date):
    return f"This report covers the time period spanning {start_date} to {end_date}"

app.run_server(debug = True)

Plotly Dash：在 Markdown 文本中显示一个变量

Plotly Dash: Display a variable inside Markdown text

python

markdown

plotly

plotly-dash