django 返回数据的几种常用姿势

django 返回数据的几种常用姿势

render

1. 传入一个html，返回一个页面

def case_list(request):
   return render(request, 'case_list.html')

2. 传入一个html，再传入一个字典，字典的key和value作用于html

home.html

<h1>欢迎{{ username }}使用 接口测试平台</h1>

views中的home函数

def home(request):
	return render(request, 'home.html', {'username': 'kangpc'})

我们想要的结果是：kangpc显示在html中的username位置

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HttpResponse

传入一个字符串，在返回的页面上显示该字符串

def home(request):
   return HttpResponse('这里是伟大的home页面')

HttpResponseRedirect

传入一个urls中配置的路由，重定向到指定的路由页面

JsonResponse

传入json对象返回给前端json，前后端分离就是用的这个姿势

from django.shortcuts import render
from django.http import HttpResponse, HttpResponseRedirect


def case_list(request):
   # return HttpResponse('这里是伟大的用例库页面')
   # return HttpResponseRedirect('/welcome/')
   return JsonResponse({'code': 0, 'data': {}, 'message': '提交成功'})

源码

class JsonResponse(HttpResponse):
    """
    An HTTP response class that consumes data to be serialized to JSON.

    :param data: Data to be dumped into json. By default only ``dict`` objects
      are allowed to be passed due to a security flaw before EcmaScript 5. See
      the ``safe`` parameter for more information.
    :param encoder: Should be a json encoder class. Defaults to
      ``django.core.serializers.json.DjangoJSONEncoder``.
    :param safe: Controls if only ``dict`` objects may be serialized. Defaults
      to ``True``.
    :param json_dumps_params: A dictionary of kwargs passed to json.dumps().
    """

    def __init__(self, data, encoder=DjangoJSONEncoder, safe=True,
                 json_dumps_params=None, **kwargs):
         # safe 参数判断数据是否为字典形式,不是字典形式则抛TypeError异常     
         #如果safe为False则利用短路操作默认为False,以下条件不执行,代表可支持dict以外形式数据
        if safe and not isinstance(data, dict):
            raise TypeError(
                'In order to allow non-dict objects to be serialized set the '
                'safe parameter to False.'
            )
        if json_dumps_params is None:
            json_dumps_params = {}
        # 设置content_type返回的数据格式为application/json
        kwargs.setdefault('content_type', 'application/json')
        # 将json_dumps_params打散,将data序列化
        data = json.dumps(data, cls=encoder, **json_dumps_params)
        super().__init__(content=data, **kwargs)

import json
data = [{'a':"A",'b':(2,4),'c':3.0}]
res = repr(data)
print ("data :", res)
data_json = json.dumps(data)
print(data_json)
执行结果：
data : [{'a': 'A', 'b': (2, 4), 'c': 3.0}]
[{"a": "A", "b": [2, 4], "c": 3.0}]
观察两次打印的结果，会发现Python对象被转成JSON字符串以后，跟原始的repr()输出的结果会有些特殊的变化，原字典中的元组被改成了json类型的数组。

# json.dump可以传递很多参数:  json.dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, 
　　　　　　separators=None, encoding="utf-8", default=None, sort_keys=False, **kw)
# json_dumps_params为字典形式, 如果json.dump需要传递参数则可以指定json_dumps_params参数
# 例: return JsonResponse(back_dic, safe=False, json_dumps_params={'ensure_ascii':False})

def dumps(obj, *, skipkeys=False, ensure_ascii=True, check_circular=True,
        allow_nan=True, cls=None, indent=None, separators=None,
        default=None, sort_keys=False, **kw):
    """Serialize ``obj`` to a JSON formatted ``str``.

    If ``skipkeys`` is true then ``dict`` keys that are not basic types
    (``str``, ``int``, ``float``, ``bool``, ``None``) will be skipped
    instead of raising a ``TypeError``.

    If ``ensure_ascii`` is false, then the return value can contain non-ASCII
    characters if they appear in strings contained in ``obj``. Otherwise, all
    such characters are escaped in JSON strings.

    If ``check_circular`` is false, then the circular reference check
    for container types will be skipped and a circular reference will
    result in an ``OverflowError`` (or worse).

    If ``allow_nan`` is false, then it will be a ``ValueError`` to
    serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in
    strict compliance of the JSON specification, instead of using the
    JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).

    If ``indent`` is a non-negative integer, then JSON array elements and
    object members will be pretty-printed with that indent level. An indent
    level of 0 will only insert newlines. ``None`` is the most compact
    representation.

    If specified, ``separators`` should be an ``(item_separator, key_separator)``
    tuple.  The default is ``(', ', ': ')`` if *indent* is ``None`` and
    ``(',', ': ')`` otherwise.  To get the most compact JSON representation,
    you should specify ``(',', ':')`` to eliminate whitespace.

    ``default(obj)`` is a function that should return a serializable version
    of obj or raise TypeError. The default simply raises TypeError.

    If *sort_keys* is true (default: ``False``), then the output of
    dictionaries will be sorted by key.

    To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
    ``.default()`` method to serialize additional types), specify it with
    the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.

    """
    # cached encoder
    if (not skipkeys and ensure_ascii and
        check_circular and allow_nan and
        cls is None and indent is None and separators is None and
        default is None and not sort_keys and not kw):
        return _default_encoder.encode(obj)
    if cls is None:
        cls = JSONEncoder
    return cls(
        skipkeys=skipkeys, ensure_ascii=ensure_ascii,
        check_circular=check_circular, allow_nan=allow_nan, indent=indent,
        separators=separators, default=default, sort_keys=sort_keys,
        **kw).encode(obj)


_default_decoder = JSONDecoder(object_hook=None, object_pairs_hook=None)