Python，解析JSON对象时正确处理Key Errors

Question

假设我想解析 100 个 json 对象并从对象中提取某个元素，例如 "author"："Mark Twain".

如果 100 个 json 对象中有 1 个缺少信息并且没有 "author" 键，则会引发键错误并停止程序。

处理此问题的最佳方法是什么？

此外，如果 json 对象中存在冗余，例如有名为 "authorFirstName" 的键："Mark" 和 'authorlastName"："Twain"，在 "author" 丢失的情况下，有没有办法使用这些而不是原来的 "author" 键？

Answer 1

如果键存在，您可以使用dict.get('key', default=None)获取值。

假设 authors.json 文件如下：

[
  {
    "author": "Mark Twain"
  },
  {
    "authorFirstName": "Mark",
    "authorLastName": "Twain"
  },
  {
    "noauthor": "error"
  }
]

您可以使用以下

import json

people = json.load(open("authors.json"))

for person in people:
    author = person.get('author')
    # If there is no author key then author will be None
    if not author:
        # Try to get the first name and last name
        fname, lname = person.get('authorFirstName'), person.get('authorLastName')
        # If both first name and last name keys were present, then combine the data into a single author name
        if fname and lname:
            author = "{} {}".format(fname, lname)

    # Now we either have an author because the author key existed, or we built it from the first and last names.
    if author is not None:
        print("Author is {}".format(author))
    else:
        print("{} does not have an author".format(person))

输出

Author is Mark Twain
Author is Mark Twain
{u'noauthor': u'error'} does not have an author

Python，解析JSON对象时正确处理Key Errors

Python, properly handle Key Errors when parsing JSON object

python

error-handling

parsing

json

key