Question

有一个对象列表，打印方式如下：

[<Intermediate_table: Intermediate_table object>, <Intermediate_table: Intermediate_table object>, <Intermediate_table: Intermediate_table object>, <Intermediate_table: Intermediate_table object>]

我想提取我使用 json.loads（queryset）的单个对象的email属性，它显示错误：期望值：第1行第1列（char 0 ）

#I also tried without json.loads: 
for i in queryset:#the list is in queryset variable
 print(i.subject)#this gives an error

该函数（在admins.py文件中，它会在此模型的管理页面上调用特定操作）：

def authenticate_(modeladmin, request, queryset):
    #q = queryset.email;
    #req = json.loads(str(queryset )    
    #q = req['email']
    for i in queryset:
        print(json.loads(str(i))) 
    print('asdasdadasd-->'+str(queryset))

错误追踪：

Traceback:
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/core/handlers/base.py" in get_response
  112.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/contrib/admin/options.py" in wrapper
  465.                 return self.admin_site.admin_view(view)(*args, **kwargs)
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/utils/decorators.py" in _wrapped_view
  99.                     response = view_func(request, *args, **kwargs)
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
  52.         response = view_func(request, *args, **kwargs)
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/contrib/admin/sites.py" in inner
  198.             return view(request, *args, **kwargs)
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/utils/decorators.py" in _wrapper
  29.             return bound_func(*args, **kwargs)
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/utils/decorators.py" in _wrapped_view
  99.                     response = view_func(request, *args, **kwargs)
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/utils/decorators.py" in bound_func
  25.                 return func(self, *args2, **kwargs2)
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/contrib/admin/options.py" in changelist_view
  1364.                 response = self.response_action(request, queryset=cl.get_queryset(request))
File "/home/saurabh/Music/Project_ques10/test/lib/python3.4/site-packages/django/contrib/admin/options.py" in response_action
  1117.             response = func(self, request, queryset)
File "/home/saurabh/Music/Project_ques10/ques10-funda/biostar/apps/quespaper/admin.py" in authenticate_
  83.         print(json.loads(str(i))) 
File "/usr/lib/python3.4/json/__init__.py" in loads
  318.         return _default_decoder.decode(s)
File "/usr/lib/python3.4/json/decoder.py" in decode
  343.         obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "/usr/lib/python3.4/json/decoder.py" in raw_decode
  361.             raise ValueError(errmsg("Expecting value", s, err.value)) from None

Exception Type: ValueError at /admin/quespaper/intermediate_table/
Exception Value: Expecting value: line 1 column 1 (char 0)

请建议解析每个对象的正确方法。

感谢。

Answer 1

问题是您尝试解码的对象首先不是json可编码的。 JSON可接受的类型是string，number，boolean，array和dict。因此，如果您将此对象转换为字符串并尝试对其进行解码，那么python将无法将其解码为正确的对象，因此会引发错误。

如果您真的想使用JSON格式，只有在首先对其进行编码后才能在字符串表示中使用它：

Measurement

您可能还需要为模型定义_str __（）方法。

没有json.loads（）的代码失败，因为您的Intermediate_table对象没有属性电子邮件。

解析django中的对象列表

1 个答案: