达世币App回调会在数据框中附加新条目，如果与之前的任何条目匹配，则替换

Question

我正在尝试构建一个破折号应用程序，该应用程序从用户那里获取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。我不确定回调中出了什么问题。 如果用户条目与任何数据框行匹配，则还尝试构建逻辑，则只有它将替换 else append。

您的帮助将得到极大的赞赏：

@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%'})

Answer 1

由于在达世币中不鼓励全局变量的突变，因此允许访问当前数据的标准方法是添加一个将数据保存为State参数的组件。它可以是单独的组件(例如Store组件(，也可以只是数据表本身。下面是一个演示后一种方法的小示例，

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关键字是新的 根据达世币1.12.0.如名称所示，它可以防止初始回调，从而消除了if clicks is not None:检查的需要。