当元素不存在时处理 JSON Parsing TypeError 的正确方法 [英] Proper way of handling JSON Parsing TypeError when element does not exist

问题描述

代码最终得到了我想要的.(这是从一个非常大的json数据集中创建一个我想要的字段的字典列表，以便我可以创建一个数据框来进行额外的数据处理)

The code get's me what I want in the end. (which is to create a list of dictionary of the fields I want from a very large json dataset, so that I can create a dataframe for additional data processing)

但是，我必须构建一个非常大的 try/expect 块才能完成此操作.我想知道是否有更清晰/更聪明的方法来做到这一点.

However I have to construct a very large try/expect block to get this done. I am was wondering if there is a clearer/clever way of doing this.

我遇到的问题是 details['element'] 有时不存在或有值，如果它在子元素上不存在，则会抛出 NoneType 异常['Value'] 无法抓取，因为它不存在.

The problem I'm having is that the details['element'] sometimes don't exist or have a value, which throws a NoneType exception if it does not exist on the child element['Value'] cannot be grabbed because it does not exist.

因此，如果发生这种情况，我有一个非常大的 try/except 块来将变量设置为 ''.

So I have a very large try/except block to set the variable to '' if that happens.

我尝试将 details['element'] 发送到一个函数，该函数将向变量输出返回值...但看起来我不能这样做，因为 Python 会检查元素是否为 NoneType 在将它传递给函数之前发生，这发生在将它发送到函数之前.

I tried to send the details['element'] to a function that would output a return value to the variable...but it looks like I can't do that, because Python checks if the element is a NoneType before passing it through the function, and this happens before sending it to the function.

有什么想法吗?

rawJson = json.loads(data.decode('utf-8'))
issues = rawJson['issues']
print('Parsing data...')
for ticket in issues:
    details = ticket['fields']

    try:
        key = ticket['key']
    except TypeError:
        key = ''
    try:
        issueType = details['issuetype']['name']
    except TypeError:
        issueType = ''
    try:
        description = details['description']
    except TypeError:
        description = ''
    try:
        status = details['status']['name']
    except TypeError:
        status = ''
    try:
        creator = details['creator']['displayName']
    except TypeError:
        creator =''
    try:
        assignee = details['assignee']['displayName']
    except TypeError:
        assignee =''
    try:
        lob = details['customfield_10060']['value']
    except TypeError:
        lob ='' 

 .... There is a long list of this

推荐答案

您可以使用 get 方法 允许提供默认值以简化此代码:

You can use get method which allows to provide a default value to simplify this code:

d = {'a': 1, 'c': 2}
value = d.get('a', 0) // value = 1 here because d['a'] exists
value = d.get('b', 0) // value = 0 here because d['b'] does not exist

所以你可以写:

for ticket in issues:
    details = ticket['fields']

    key = ticket.get('key', '')
    description = details.get('description', '')
    issueType = details['issuetype'].get('name') if 'issuetype' in details else ''

    ...

这篇关于当元素不存在时处理 JSON Parsing TypeError 的正确方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！