Django(三)：HttpRequest和HttpResponse

　　当一个请求连接进来时，django会创建一个HttpRequest对象来封装和保存所有请求相关的信息，并且会根据请求路由载入匹配的视图函数。每个请求的视图函数都会返回一个HttpResponse。

　　HttpRequest和HttpResponse可以从django.http中导入。

　　1、HttpRequest类

函数	功能描述
HttpRequest.scheme	请求协议（http或者https）
HttpRequest.body	以字节的方式返回请求体内容；可以通过HttpRequest.POST获取处理后的key和value，也可以通过HttpRequest.read()格式化
HttpRequest.path	返回请求的完整路径，不包括协议和域名
HttpRequest.GET	GET请求参数，返回一个queryDict对象
HttpRequest.POST	获取表单提交的数据，如果是通过POST请求提交的其它非表单数据，可以使用HttpRequest.Body获取；使用时可以通过if request.method == "PSOT"来进行预判断
HttpRequest.method	返回请求方式
HttpRequest.environ	返回一个字典，包含所有django运行的环境信息
HttpRequest.content_type	文件格式
HttpRequest.content_params	参数
HttpRequest.COOKIES	返回一个字典，包含浏览器存储的所有cookie
HttpRequest.FILES	返回一个MultiValueDict，包含上传的文件
HttpRequest.META	返回一个包含所有请求相关信息的字典(包含Headers)，同environ
HttpRequest.resolver_match	返回请求处理的url及相关参数
HttpRequest.session	中间件，设置session，一个可读可写的字典对象
HttpRequest.get_host()	获取请求的主机和端口
HttpRequest.get_port()	获取端口
HttpRequest.get_full_path()	返回完整路径，同path
HttpRequest.get_signed_cookie(key, default=RAISE_ERROR, salt='', max_age=None)	获取以一个cookie
HttpRequest.is_ajax()	判断是否为ajax请求
HttpRequest.is_secure()	判断是否为https请求

　　示例：

class HttpRequest:
    """A basic HTTP request."""

    # The encoding used in GET/POST dicts. None means use default setting.
    _encoding = None
    _upload_handlers = []

    def __init__(self):
        # WARNING: The `WSGIRequest` subclass doesn't call `super`.
        # Any variable assignment made here should also happen in
        # `WSGIRequest.__init__()`.

        self.GET = QueryDict(mutable=True)
        self.POST = QueryDict(mutable=True)
        self.COOKIES = {}
        self.META = {}
        self.FILES = MultiValueDict()

        self.path = ''
        self.path_info = ''
        self.method = None
        self.resolver_match = None
        self._post_parse_error = False
        self.content_type = None
        self.content_params = None

    def __repr__(self):
        if self.method is None or not self.get_full_path():
            return '<%s>' % self.__class__.__name__
        return '<%s: %s %r>' % (self.__class__.__name__, self.method, self.get_full_path())

    def _get_raw_host(self):
        """
        Return the HTTP host using the environment or request headers. Skip
        allowed hosts protection, so may return an insecure host.
        """
        # We try three options, in order of decreasing preference.
        if settings.USE_X_FORWARDED_HOST and (
                'HTTP_X_FORWARDED_HOST' in self.META):
            host = self.META['HTTP_X_FORWARDED_HOST']
        elif 'HTTP_HOST' in self.META:
            host = self.META['HTTP_HOST']
        else:
            # Reconstruct the host using the algorithm from PEP 333.
            host = self.META['SERVER_NAME']
            server_port = self.get_port()
            if server_port != ('' if self.is_secure() else ''):
                host = '%s:%s' % (host, server_port)
        return host

    def get_host(self):
        """Return the HTTP host using the environment or request headers."""
        host = self._get_raw_host()

        # Allow variants of localhost if ALLOWED_HOSTS is empty and DEBUG=True.
        allowed_hosts = settings.ALLOWED_HOSTS
        if settings.DEBUG and not allowed_hosts:
            allowed_hosts = ['localhost', '127.0.0.1', '[::1]']

        domain, port = split_domain_port(host)
        if domain and validate_host(domain, allowed_hosts):
            return host
        else:
            msg = "Invalid HTTP_HOST header: %r." % host
            if domain:
                msg += " You may need to add %r to ALLOWED_HOSTS." % domain
            else:
                msg += " The domain name provided is not valid according to RFC 1034/1035."
            raise DisallowedHost(msg)

    def get_port(self):
        """Return the port number for the request as a string."""
        if settings.USE_X_FORWARDED_PORT and 'HTTP_X_FORWARDED_PORT' in self.META:
            port = self.META['HTTP_X_FORWARDED_PORT']
        else:
            port = self.META['SERVER_PORT']
        return str(port)

    def get_full_path(self, force_append_slash=False):
        # RFC 3986 requires query string arguments to be in the ASCII range.
        # Rather than crash if this doesn't happen, we encode defensively.
        return '%s%s%s' % (
            escape_uri_path(self.path),
            '/' if force_append_slash and not self.path.endswith('/') else '',
            ('?' + iri_to_uri(self.META.get('QUERY_STRING', ''))) if self.META.get('QUERY_STRING', '') else ''
        )

    def get_signed_cookie(self, key, default=RAISE_ERROR, salt='', max_age=None):
        """
        Attempt to return a signed cookie. If the signature fails or the
        cookie has expired, raise an exception, unless the `default` argument
        is provided,  in which case return that value.
        """
        try:
            cookie_value = self.COOKIES[key]
        except KeyError:
            if default is not RAISE_ERROR:
                return default
            else:
                raise
        try:
            value = signing.get_cookie_signer(salt=key + salt).unsign(
                cookie_value, max_age=max_age)
        except signing.BadSignature:
            if default is not RAISE_ERROR:
                return default
            else:
                raise
        return value

    def get_raw_uri(self):
        """
        Return an absolute URI from variables available in this request. Skip
        allowed hosts protection, so may return insecure URI.
        """
        return '{scheme}://{host}{path}'.format(
            scheme=self.scheme,
            host=self._get_raw_host(),
            path=self.get_full_path(),
        )

    def build_absolute_uri(self, location=None):
        """
        Build an absolute URI from the location and the variables available in
        this request. If no ``location`` is specified, bulid the absolute URI
        using request.get_full_path(). If the location is absolute, convert it
        to an RFC 3987 compliant URI and return it. If location is relative or
        is scheme-relative (i.e., ``//example.com/``), urljoin() it to a base
        URL constructed from the request variables.
        """
        if location is None:
            # Make it an absolute url (but schemeless and domainless) for the
            # edge case that the path starts with '//'.
            location = '//%s' % self.get_full_path()
        bits = urlsplit(location)
        if not (bits.scheme and bits.netloc):
            current_uri = '{scheme}://{host}{path}'.format(scheme=self.scheme,
                                                           host=self.get_host(),
                                                           path=self.path)
            # Join the constructed URL with the provided location, which will
            # allow the provided ``location`` to apply query strings to the
            # base path as well as override the host, if it begins with //
            location = urljoin(current_uri, location)
        return iri_to_uri(location)

    def _get_scheme(self):
        """
        Hook for subclasses like WSGIRequest to implement. Return 'http' by
        default.
        """
        return 'http'

    @property
    def scheme(self):
        if settings.SECURE_PROXY_SSL_HEADER:
            try:
                header, value = settings.SECURE_PROXY_SSL_HEADER
            except ValueError:
                raise ImproperlyConfigured(
                    'The SECURE_PROXY_SSL_HEADER setting must be a tuple containing two values.'
                )
            if self.META.get(header) == value:
                return 'https'
        return self._get_scheme()

    def is_secure(self):
        return self.scheme == 'https'

    def is_ajax(self):
        return self.META.get('HTTP_X_REQUESTED_WITH') == 'XMLHttpRequest'

    @property
    def encoding(self):
        return self._encoding

    @encoding.setter
    def encoding(self, val):
        """
        Set the encoding used for GET/POST accesses. If the GET or POST
        dictionary has already been created, remove and recreate it on the
        next access (so that it is decoded correctly).
        """
        self._encoding = val
        if hasattr(self, 'GET'):
            del self.GET
        if hasattr(self, '_post'):
            del self._post

    def _initialize_handlers(self):
        self._upload_handlers = [uploadhandler.load_handler(handler, self)
                                 for handler in settings.FILE_UPLOAD_HANDLERS]

    @property
    def upload_handlers(self):
        if not self._upload_handlers:
            # If there are no upload handlers defined, initialize them from settings.
            self._initialize_handlers()
        return self._upload_handlers

    @upload_handlers.setter
    def upload_handlers(self, upload_handlers):
        if hasattr(self, '_files'):
            raise AttributeError("You cannot set the upload handlers after the upload has been processed.")
        self._upload_handlers = upload_handlers

    def parse_file_upload(self, META, post_data):
        """Return a tuple of (POST QueryDict, FILES MultiValueDict)."""
        self.upload_handlers = ImmutableList(
            self.upload_handlers,
            warning="You cannot alter upload handlers after the upload has been processed."
        )
        parser = MultiPartParser(META, post_data, self.upload_handlers, self.encoding)
        return parser.parse()

    @property
    def body(self):
        if not hasattr(self, '_body'):
            if self._read_started:
                raise RawPostDataException("You cannot access body after reading from request's data stream")

            # Limit the maximum request data size that will be handled in-memory.
            if (settings.DATA_UPLOAD_MAX_MEMORY_SIZE is not None and
                    int(self.META.get('CONTENT_LENGTH') or 0) > settings.DATA_UPLOAD_MAX_MEMORY_SIZE):
                raise RequestDataTooBig('Request body exceeded settings.DATA_UPLOAD_MAX_MEMORY_SIZE.')

            try:
                self._body = self.read()
            except IOError as e:
                raise UnreadablePostError(*e.args) from e
            self._stream = BytesIO(self._body)
        return self._body

    def _mark_post_parse_error(self):
        self._post = QueryDict()
        self._files = MultiValueDict()
        self._post_parse_error = True

    def _load_post_and_files(self):
        """Populate self._post and self._files if the content-type is a form type"""
        if self.method != 'POST':
            self._post, self._files = QueryDict(encoding=self._encoding), MultiValueDict()
            return
        if self._read_started and not hasattr(self, '_body'):
            self._mark_post_parse_error()
            return

        if self.content_type == 'multipart/form-data':
            if hasattr(self, '_body'):
                # Use already read data
                data = BytesIO(self._body)
            else:
                data = self
            try:
                self._post, self._files = self.parse_file_upload(self.META, data)
            except MultiPartParserError:
                # An error occurred while parsing POST data. Since when
                # formatting the error the request handler might access
                # self.POST, set self._post and self._file to prevent
                # attempts to parse POST data again.
                # Mark that an error occurred. This allows self.__repr__ to
                # be explicit about it instead of simply representing an
                # empty POST
                self._mark_post_parse_error()
                raise
        elif self.content_type == 'application/x-www-form-urlencoded':
            self._post, self._files = QueryDict(self.body, encoding=self._encoding), MultiValueDict()
        else:
            self._post, self._files = QueryDict(encoding=self._encoding), MultiValueDict()

    def close(self):
        if hasattr(self, '_files'):
            for f in chain.from_iterable(l[1] for l in self._files.lists()):
                f.close()

    # File-like and iterator interface.
    #
    # Expects self._stream to be set to an appropriate source of bytes by
    # a corresponding request subclass (e.g. WSGIRequest).
    # Also when request data has already been read by request.POST or
    # request.body, self._stream points to a BytesIO instance
    # containing that data.

    def read(self, *args, **kwargs):
        self._read_started = True
        try:
            return self._stream.read(*args, **kwargs)
        except IOError as e:
            raise UnreadablePostError(*e.args) from e

    def readline(self, *args, **kwargs):
        self._read_started = True
        try:
            return self._stream.readline(*args, **kwargs)
        except IOError as e:
            raise UnreadablePostError(*e.args) from e

    def __iter__(self):
        while True:
            buf = self.readline()
            if not buf:
                break
            yield buf

    def xreadlines(self):
        warnings.warn(
            'HttpRequest.xreadlines() is deprecated in favor of iterating the '
            'request.', RemovedInDjango30Warning, stacklevel=2,
        )
        yield from self

    def readlines(self):
        return list(self)

HttpRequest源码

from django.http import HttpResponse
from django.views.decorators.csrf import csrf_exempt

# views.py
@csrf_exempt
def page(request):
    # print(request.scheme)
    # print(request.GET)
    # print(request.POST)
    # print(request.method)
    # # print(request.encoding)
    # print(request.environ)
    # print(request.content_type)
    # print(request.content_params)
    # request.COOKIES["host"] = "whatever"
    # print(request.COOKIES)
    # print(request.FILES)
    # print(request.FILES.get("dog"))
    # print(request.META)
    # print(request.resolver_match)
    # request.session["username"] = "Jan"
    # print(request.session["username"])
    # print(request.get_signed_cookie("host"))
    # print(request.is_secure())
    # print(request.is_ajax())

    # print(request.POST.get("age", None))
    # print(request.get_port())
    # print(request.get_full_path())
    # print(request.path)
    # print(request.path_info)
    # print(request.get_host())
    # print(request.GET.get("name", None))
    return HttpResponse("OK!")

　　使用httpie测试：

# GET请求带参数
http http://127.0.0.1:8000/page/ -- name=Jan
# PSOT请求
http -f POST 127.0.0.1:/page/ age=
# POST上传文件
http -f POST http://127.0.0.1:8000/page/  dog@Desktop/dog.png

　　2、queryDict对象

　　queryDict类是python字典的子类，具有字典的所有方法，它放在django.http.QueryDict中。它用“&”分割字符传，用“=”生成键值对，从而将一个类似GET请求参数的字符串解析成一个类似字典的对象。源码如下：

class QueryDict(MultiValueDict):
    """
    A specialized MultiValueDict which represents a query string.

    A QueryDict can be used to represent GET or POST data. It subclasses
    MultiValueDict since keys in such data can be repeated, for instance
    in the data from a form with a <select multiple> field.

    By default QueryDicts are immutable, though the copy() method
    will always return a mutable copy.

    Both keys and values set on this class are converted from the given encoding
    (DEFAULT_CHARSET by default) to str.
    """

    # These are both reset in __init__, but is specified here at the class
    # level so that unpickling will have valid values
    _mutable = True
    _encoding = None

    def __init__(self, query_string=None, mutable=False, encoding=None):
        super().__init__()
        if not encoding:
            encoding = settings.DEFAULT_CHARSET
        self.encoding = encoding
        query_string = query_string or ''
        parse_qsl_kwargs = {
            'keep_blank_values': True,
            'fields_limit': settings.DATA_UPLOAD_MAX_NUMBER_FIELDS,
            'encoding': encoding,
        }
        if isinstance(query_string, bytes):
            # query_string normally contains URL-encoded data, a subset of ASCII.
            try:
                query_string = query_string.decode(encoding)
            except UnicodeDecodeError:
                # ... but some user agents are misbehaving :-(
                query_string = query_string.decode('iso-8859-1')
        for key, value in limited_parse_qsl(query_string, **parse_qsl_kwargs):
            self.appendlist(key, value)
        self._mutable = mutable

    @classmethod
    def fromkeys(cls, iterable, value='', mutable=False, encoding=None):
        """
        Return a new QueryDict with keys (may be repeated) from an iterable and
        values from value.
        """
        q = cls('', mutable=True, encoding=encoding)
        for key in iterable:
            q.appendlist(key, value)
        if not mutable:
            q._mutable = False
        return q

    @property
    def encoding(self):
        if self._encoding is None:
            self._encoding = settings.DEFAULT_CHARSET
        return self._encoding

    @encoding.setter
    def encoding(self, value):
        self._encoding = value

    def _assert_mutable(self):
        if not self._mutable:
            raise AttributeError("This QueryDict instance is immutable")

    def __setitem__(self, key, value):
        self._assert_mutable()
        key = bytes_to_text(key, self.encoding)
        value = bytes_to_text(value, self.encoding)
        super().__setitem__(key, value)

    def __delitem__(self, key):
        self._assert_mutable()
        super().__delitem__(key)

    def __copy__(self):
        result = self.__class__('', mutable=True, encoding=self.encoding)
        for key, value in self.lists():
            result.setlist(key, value)
        return result

    def __deepcopy__(self, memo):
        result = self.__class__('', mutable=True, encoding=self.encoding)
        memo[id(self)] = result
        for key, value in self.lists():
            result.setlist(copy.deepcopy(key, memo), copy.deepcopy(value, memo))
        return result

    def setlist(self, key, list_):
        self._assert_mutable()
        key = bytes_to_text(key, self.encoding)
        list_ = [bytes_to_text(elt, self.encoding) for elt in list_]
        super().setlist(key, list_)

    def setlistdefault(self, key, default_list=None):
        self._assert_mutable()
        return super().setlistdefault(key, default_list)

    def appendlist(self, key, value):
        self._assert_mutable()
        key = bytes_to_text(key, self.encoding)
        value = bytes_to_text(value, self.encoding)
        super().appendlist(key, value)

    def pop(self, key, *args):
        self._assert_mutable()
        return super().pop(key, *args)

    def popitem(self):
        self._assert_mutable()
        return super().popitem()

    def clear(self):
        self._assert_mutable()
        super().clear()

    def setdefault(self, key, default=None):
        self._assert_mutable()
        key = bytes_to_text(key, self.encoding)
        default = bytes_to_text(default, self.encoding)
        return super().setdefault(key, default)

    def copy(self):
        """Return a mutable copy of this object."""
        return self.__deepcopy__({})

    def urlencode(self, safe=None):
        """
        Return an encoded string of all query string arguments.

        `safe` specifies characters which don't require quoting, for example::

            >>> q = QueryDict(mutable=True)
            >>> q['next'] = '/a&b/'
            >>> q.urlencode()
            'next=%2Fa%26b%2F'
            >>> q.urlencode(safe='/')
            'next=/a%26b/'
        """
        output = []
        if safe:
            safe = force_bytes(safe, self.encoding)

            def encode(k, v):
                return '%s=%s' % ((quote(k, safe), quote(v, safe)))
        else:
            def encode(k, v):
                return urlencode({k: v})
        for k, list_ in self.lists():
            k = force_bytes(k, self.encoding)
            output.extend(encode(k, force_bytes(v, self.encoding))
                          for v in list_)
        return '&'.join(output)

　　示例：

from django.http import QueryDict

# 添加django的环境配置
import os, django
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "restful.settings")
django.setup()

get_vactors = "a=1&a=2&a=3&b=Jan&b=Li&c=20"
query = QueryDict(get_vactors, mutable=True)
# print(query)

# 根据键生成新的QueryDict
query_new = QueryDict.fromkeys(query, value="这个大傻子")
# print(query_new)

# 获取键列表、值列表、键值对列表(值列表中的最后一个元素)
print(list(query.items()))    # 生成器，获取包含键和最后一个值元素的元组的列表
print(list(query.keys()))     # dict_keys，获取键
print(list(query.values()))   # 生成器，获取每个键的最后一个元素值
# 键值对
print(list(query.lists()))    # 获取键键值对列表
print(dict(query))            # 转成字典，相当于query.dict()

# 获取单个元素及列表
alist = query.get("a")
print(alist)  # 获取最后一个元素值
alist = query.getlist("a")
print(alist)  # 获取键对应的value，返回元素列表

# 添加/修改键值对，必须将mutable设置为True
query.setlist("a", [4, 5, 6])
query.setlistdefault("d", [4,5,6])
query.appendlist("e", ["this", "is", "append"])
print(query)

# 删除键值对
query.pop("e")   # 删除指定键值对
print(query)
query.popitem()  # 删除最后一个键值对
print(query)

　　3、HttpResponse

　　HttpResponse类用于设置响应头和响应内容，同样封装在django.http模块中。它分为实例化对象、填充设置以及返回三个部分。它同时也是其它请求响应类的父类。

from django.http import HttpResponse

# 添加django的环境配置
import os, django
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "restful.settings")
django.setup()

# 实例化一:
responseOne = HttpResponse("this is a http response")
# 实例化二:
responseTwo = HttpResponse()
responseTwo.write("this is another http response")
responseTwo.writelines(["this is second line", "this is third line"])
# 设置响应头
responseOne["Age"] = 20
responseOne["app"] = "sample"
del responseOne["app"]

# 设置响应头
responseOne["content_type"] = 'application/vnd.ms-excel'
responseOne['Content-Disposition'] = 'attachment; filename="foo.xls"'

responseOne.set_cookie("date", "2018-08-21", path="/page", )   # 设置cookie
responseOne.delete_cookie("date")                              # 删除cookie
# 有关对象
print(responseOne)                  # HttpResponse
print(responseOne.items())          # dict_values
print(responseOne.cookies)          # cookie
print(responseOne.content)          # 内容(字节)
print(responseOne.charset)          # 编码
print(responseOne.status_code)      # 状态码
print(responseOne.streaming)        # 是否为流
print(responseOne.closed)           # 是否已发送response
print(responseOne.serialize())      # 序列化响应头和相应内容
print(responseOne.serialize_headers())  # 序列化响应头
print(responseOne.get("Age"))       # 获取响应头中的某个键值对
print(responseTwo.getvalue())       # 获取相应的内容

# 将response设置为流数据处理
responseTwo.readable()
responseTwo.seekable()
responseTwo.write("...")

　　其它继承HttpResponse的子类包括：

HttpResponseRedirect                          # 重定向
HttpResponsePermanentRedirect                 # 永久重定向
HttpResponseNotModified                       #
HttpResponseBadRequest                        #
HttpResponseNotFound                          #
HttpResponseForbidden                         #
HttpResponseNotAllowed                        #
HttpResponseGone                              #
HttpResponseServerError                       #

　　4、JsonResponse

　　返回一个序列化的JSON对象。对于列表、字符串等，它会自动生成索引-元素JSON；对于字典，会直接生成相应的JSON。

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):
        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 = {}
        kwargs.setdefault('content_type', 'application/json')
        data = json.dumps(data, cls=encoder, **json_dumps_params)
        super().__init__(content=data, **kwargs)

　　DjangoJSONEncoder是内置的JSON编码方式，也支持传入自己写的编码方式对数据进行序列化。

# python manage.py shell
from django.http import JsonResponse
response = JsonResponse({'foo': 'bar'})
response.content

from django.http import  JsonResponse
from django.views.decorators.csrf import csrf_exempt

@csrf_exempt
def page(request):
    # lis = list(range(10))
    # return JsonResponse(lis, safe=False)
    # dic = {"name": "Jan", "age": 20}
    # return JsonResponse(dic)
    string = "this is json response"
    return JsonResponse(string, safe=False)

　　5、FileResponse

from django.http import FileResponse
response = FileResponse(open('myfile.png', 'rb'))