使用json文件保存类示例- Python

c6ubokkw 于 2022-12-30 发布在 Python

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这是我当前使用的类

class Book:
   def __init__(self, title: str, author: str, isbn: int, genre: str, numCopies: int):
      self._title = title
      self._author = author
      self._isbn = isbn
      self._genre = genre
      self._numCopies = numCopies

   def __str__(self):  # all the properties of the class Book()
      return f'Title: {self._title}\nAuthor: {self._author}\nISBN: {self._isbn}\nGenre: {self._genre}\nNumber Of Copies: {self._numCopies}\n'

json文件格式是这样给我的：

[
  {
    "title": "How to love",
    "author": "vagabondage3",
    "isbn" : 9832,
    "genre" : "Comedy",
    "numofcopies" : 2
  },
  {
    "title": "How to eat",
    "author": "belabor",
    "isbn" : 2345,
    "genre" : "Documentary",
    "numofcopies" : 3
  }
]

目标是创建一个类示例book = Book("title","author",0,"genre",0)，然后将其添加到json文件，如下所示：

[
  {
    "title": "How to love",
    "author": "vagabondage3",
    "isbn" : 9832,
    "genre" : "Comedy",
    "numofcopies" : 2
  },
  {
    "title": "How to eat",
    "author": "belabor",
    "isbn" : 2345,
    "genre" : "Documentary",
    "numofcopies" : 3
  },
  {
    "title": "title",
    "author": "author",
    "isbn" : 0,
    "genre" : "genre",
    "numofcopies" : 0
   }
]

公平地说，我看到过类似的解决方案，但我不能完全理解任何东西

JSON

来源：https://stackoverflow.com/questions/74939603/saving-class-instances-with-json-file-python

1条答案

按热度按时间

agxfikkp1#

可以使用json.loads从JSON中获取字典，然后像在常规字典中一样添加新对象。

class Book:
    def __init__(self, title: str, author: str, isbn: int, genre: str, numCopies: int):
      ...

    def get_dict(self):
        dict_obj = {
            "title": self._title,
            "author": self._author,
            "isbn" : self._isbn,
            "genre" : self._genre,
            "numofcopies" : self.__numCopies
            }

        return dict_obj

现在调用get_dict方法获取字典就足够了，并通过“append”将其添加到列表中。

if __name__ == '__main__':
    with open('your.json', 'r') as f:
        books_json = f.read()

    books = json.loads(books_json)
    book = Book('title', 'author', 0, 'genre', 0)
    books.append(book.get_dict())

    with open('your.json', 'w') as f:
        f.write(json.dumps(books))

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使用json文件保存类示例- Python

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