Django 模型不是 ajax 可序列化的 [英] Django models are not ajax serializable

问题描述

我有一个简单的视图，我用它来试验 AJAX.

I have a simple view that I'm using to experiment with AJAX.

def get_shifts_for_day(request,year,month,day):

    data= dict()
    data['d'] =year
    data['e'] = month
    data['x'] = User.objects.all()[2]

    return HttpResponse(simplejson.dumps(data), mimetype='application/javascript')

这将返回以下内容:

TypeError at /sched/shifts/2009/11/9/

<User: someguy> is not JSON serializable

如果我取出 data['x'] 行，这样我就不会引用任何模型，它会起作用并返回:

If I take out the data['x'] line so that I'm not referencing any models it works and returns this:

{"e": "11", "d": "2009"}

为什么 simplejson 不能解析我的默认 django 模型之一?我使用的任何模型都会得到相同的行为.

Why can't simplejson parse my one of the default django models? I get the same behavior with any model I use.

推荐答案

你只需要在你的 .dumps 调用中添加一个 default=encode_myway 参数来让simplejson 知道当你向它传递它不知道的类型的数据时该怎么做——你为什么"问题的答案当然是你没有告诉穷simplejson 如何处理您的模型实例之一.

You just need to add, in your .dumps call, a default=encode_myway argument to let simplejson know what to do when you pass it data whose types it does not know -- the answer to your "why" question is of course that you haven't told poor simplejson what to DO with one of your models' instances.

当然你需要编写 encode_myway 来提供 JSON 可编码的数据，例如:

And of course you need to write encode_myway to provide JSON-encodable data, e.g.:

def encode_myway(obj):
  if isinstance(obj, User):
    return [obj.username,
            obj.firstname,
            obj.lastname,
            obj.email]
    # and/or whatever else
  elif isinstance(obj, OtherModel):
    return [] # whatever
  elif ...
  else:
    raise TypeError(repr(obj) + " is not JSON serializable")

基本上，JSON 知道非常基本的数据类型(字符串、整数和浮点数，分组为字典和列表)——作为应用程序员，您有责任将其他所有内容与这些基本数据类型进行匹配，并在 simplejson 通常通过在 dump 或 dumps 时间传递给 default= 的函数完成.

Basically, JSON knows about VERY elementary data types (strings, ints and floats, grouped into dicts and lists) -- it's YOUR responsibility as an application programmer to match everything else into/from such elementary data types, and in simplejson that's typically done through a function passed to default= at dump or dumps time.

或者，您可以使用 Django 中的 json 序列化程序，请参阅 文档.

Alternatively, you can use the json serializer that's part of Django, see the docs.

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