Python 从 JSON 文件迭代字典时出现 KeyError

Question

我正在尝试读取一个 JSON 文件（并最终将内容保存到数据库），但是当运行下面的代码时，我得到了一个 KeyError。 See sample JSON供参考。

'durationTimeFrom' 和 'durationTimeTo' 键在 JSON 文件中并非在所有情况下都存在（我认为仅当 eventType 为 80 时） .

如何在尝试读取值之前正确识别丢失的键，and/or如何为还没有键的项目插入虚拟键？

我已经搜索了 Google/Whosebug 并尝试了 if key in dict: 和 dict.get(key) 但没有成功。

import json

source = "feed_traffic.json" # JSON file to process
data = json.loads(open(source).read()) # Process JSON

total = data["events"]["totalCount"]
index = 0

events = data["events"]["list"][index:total]

for event in events:

    eid = event["id"]
    type = event['eventType']
    header = event['headingText']
    lat = event['latitude']
    long = event['longitude']
    created = event['created']
    updated = event['updated']
    expires = event['expireTime']
    validFrom = event['durationTimeFrom']
    validTo = event['durationTimeTo']
    status = event['status']

    # Just to check all is well, out data in console
    print("Traffic Event", index, ":", eid, "-", type, "-", header, "(", long, ",", lat, ")")

    index = index+1

Answer 1

dict.get。这对我来说可以。你应该改变如下。

# before
validFrom = event['durationTimeFrom']
validTo = event['durationTimeTo']

# after
validFrom = event.get('durationTimeFrom')
validTo = event.get('durationTimeTo')

Python 从 JSON 文件迭代字典时出现 KeyError

Python KeyError when iterating dict from JSON-file

python

json

dictionary

keyerror