更新价格附加信息会删除旧的价格附加信息

Question

我编写了一个脚本，每天将价格附加信息上传到我的广告系列中。但是由于某种原因，应用运算符SET导致旧扩展名被删除。

我想运行一次（使用操作符ADD），然后使用SET更新扩展名。我该怎么办？

以下代码：

def add_price_extension(adwords, campaign_id, table_rows):
    # table_rows as an argument to the function!

    if len(table_rows) < 3:
        raise errors.GoogleAdsError('Not enough table rows (minimum: 3)')

    elif len(table_rows) > 8:
        raise errors.GoogleAdsError('Too many table rows (maximum: 8)')


    service = adwords.client.GetService('CampaignExtensionSettingService', version = 'v201806')
    operations = [{
        'operator': 'SET',
        'operand': {
            'campaignId': campaign_id,
            'extensionType': 'PRICE',
            'extensionSetting': {
                'extensions': [{
                    'xsi_type': 'PriceFeedItem',
                    'priceExtensionType': 'PRODUCT_CATEGORIES',
                    'language': 'pt-BR',
                    'campaignTargeting': {
                        'TargetingCampaignId': campaign_id
                    },
                    'scheduling': {
                        'feedItemSchedules': [
                            {
                                'dayOfWeek': day_of_week,
                                'startHour': 0,
                                'startMinute': 'ZERO',
                                'endHour': 24,
                                'endMinute': 'ZERO',
                            } for day_of_week in [
                                'MONDAY', 'TUESDAY', 'WEDNESDAY', 'THURSDAY',
                                'FRIDAY', 'SATURDAY', 'SUNDAY'
                            ]
                        ]
                    },
                    'tableRows': table_rows,
                    'priceQualifier': 'FROM',
                }]
            }
        }
    }]

    response = service.mutate(operations)

    if 'value' in response:
        print('Extension setting with type "%s" was added to the campaign with ID %d.'
              % (response['value'][0]['extensionType'], campaign_id))
    else:
        raise errors.GoogleAdsError('No extension settings were added.')

我尝试使用名为FIRST_TIME的常量，并在第一次运行时将其设置为True，然后将其设置为False。但是我对将其传递给函数有些困惑。

FIRST_TIME = True

def add_price_extension(adwords, campaign_id, table_rows, first_time = FIRST_TIME):

...

    operations = [{
        if first_time:
            'operator': 'ADD'
        else:
            'operator': 'SET',
        'operand': { 
...

谢谢。