Dash App 回调在数据框中追加新条目并替换与任何先前条目匹配的条目 [英] Dash App call back append new entry in data frame and replace if matches with any previous entry

问题描述

我正在尝试构建一个破折号应用程序，它接受用户的输入并将每个条目附加到数据框中，但它正在替换旧条目并生成一个新条目.我不确定回调中有什么问题.还尝试构建一个逻辑，如果用户条目与数据框的任何行匹配，那么它只会替换 else append.

I am trying to build a dash app which takes input from users and append each entry in the data frame, but it's replacing the old entry and generating a new one. I am not sure what's wrong in the callback. also trying to build a logic if the user entry matches with any row of data frame then only it will replace else append.

非常感谢您的帮助:

@app.callback(Output('save-query', 'children'),
              [Input('save', 'n_clicks')],
              [State('ad_account_id', 'value'),
               State('app_id', 'value'),
               State('access_token', 'value'),
               State('app_secret', 'value'),
               State('metrics', 'value'),
               State('breakdown', 'value'),
               State('start-date', 'date'),
               State('end-date', 'date'),
               State('save-as', 'value')
               ],
              )
def save_query(clicks, ad_account_id, app_id, access_token, app_secret, metrics, breakdown,
               start_date, end_date, save):
    if clicks is not None:
        my_ad_account = ad_account_id
        my_app_id = app_id
        my_access_token = access_token
        my_app_secret = app_secret
        my_metrics = metrics
        my_breakdown = breakdown
        my_start_date = start_date
        my_end_date = end_date
        my_save = str.lower(save)
        data = [[my_save, my_ad_account, my_app_id, my_access_token, my_app_secret, my_metrics, my_breakdown,
                 my_start_date,
                 my_end_date]]
        df = pd.DataFrame(data, columns=['report_name', 'ad_account', 'app_id', 'access_token',
                                         'app_secret', 'metrics', 'breakdown',
                                         'start_date', 'end_date'])

        dff = df.append(df)

        return html.Div([
            dash_table.DataTable(
                css=[{'selector': '.row',
                      'rule': 'margin: 0; white-space: inherit; overflow: inherit; text-overflow: inherit;'}],
                id='table',
                columns=[{"name": i, "id": i} for i in dff.columns],
                data=dff.to_dict("rows"), )],
            style={'margin-top': 30, 'display': 'inline-block', 'margin-left': 20, 'width': '100%'})

推荐答案

由于全局变量的变异是 在 Dash 中不鼓励，启用对当前数据的访问的标准方法是添加一个将数据保存为 State 参数的组件.它可以是一个单独的组件(例如一个 Store 组件)或仅仅是数据表本身.这是一个演示后一种方法的小例子，

Since mutation of global variables is discouraged in Dash, the standard approach to enable access the to current data would be to add a component that holds the data as a State argument. It could be a separate component (such as a Store component) or simply the data table itself. Here is a small example demonstrating the latter approach,

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

user_key = 'access_token'
# Setup table.
columns = ['report_name', 'ad_account', 'app_id', 'access_token']
table = dash_table.DataTable(columns=[{"name": column, "id": column} for column in columns], data=[], id="table")
# Create app.
app = dash.Dash(prevent_initial_callbacks=True)
app.layout = html.Div([dcc.Input(id=column, value=column) for column in columns] +
                      [html.Button("Save", id="save"), dcc.Store(id="cache", data=[]), table])


@app.callback(Output("table", "data"), [Input("save", "n_clicks")], [State("table", "data")] +
              [State(column, "value") for column in columns])
def append(n_clicks, data, *args):
    record = {columns[i]: arg for i, arg in enumerate(list(args))}
    # If the record (identified by user_key) already exists, update it.
    try:
        record_index = [record[user_key] for record in data].index(record[user_key])
        data[record_index] = record
    # Otherwise, append it.
    except ValueError:
        data.append({columns[i]: arg for i, arg in enumerate(list(args))})
    # Return the updated data.
    return data


if __name__ == '__main__':
    app.run_server()

作为旁注，prevent_initial_callbacks 关键字是 Dash 1.12.0 中的新关键字.顾名思义，它阻止了初始回调，从而消除了对 if clicks is not None: 检查的需要.

As a sidenote, the prevent_initial_callbacks keyword is new as per Dash 1.12.0. As indicated by the name, it prevents the initial callback, thereby eliminating the need for the if clicks is not None: check.

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