defaultdict键默认值问题

Question

我是Python的新手，对defaultdict有问题。 我有一些json，其中lastInspection键并不总是存在。我需要在日期中输入默认值。

p.get("lastInspection", "")返回我{'date': '2018-01-03'}

problem = [{'lastInspection': {'date': '2018-01-03'}, 'contacts': []}]

for p in problem:
    print(p.get("lastInspection", ""))
    print(p.get("date", ""))

Answer 1

我正在猜测，defaultdict不是您要使用的。

默认值应在get方法的第二个参数中声明。

problem = [{'lastInspection': {'date': '2018-01-03'}, 'contacts': []}]
default_inspection = { 'date': '2018-01-03' }

for p in problem:
    # default_inspection is returned, when 'lastInspection' is not present in the json
    inspection = p.get("lastInspection", default_inspection)
    print(inspection)
    # now you access date, as you are sure, that it is present
    print(inspection['date'])