class APIView(View):
# The following policies may be set at either globally, or per-view.
renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES
# 解析器類s
parser_classes = api_settings.DEFAULT_PARSER_CLASSES
# 認證類s
authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES
# 限制通路類s
throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES
# 權限類s
permission_classes = api_settings.DEFAULT_PERMISSION_CLASSES
content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS
metadata_class = api_settings.DEFAULT_METADATA_CLASS
# 版本類
versioning_class = api_settings.DEFAULT_VERSIONING_CLASS
# Allow dependency injection of other settings to make testing easier.
settings = api_settings
schema = AutoSchema()
@classmethod
def as_view(cls, **initkwargs):
"""
Store the original class on the view function.
This allows us to discover information about the view when we do URL
reverse lookups. Used for breadcrumb generation.
"""
if isinstance(getattr(cls, 'queryset', None), models.query.QuerySet):
def force_evaluation():
raise RuntimeError(
'Do not evaluate the `.queryset` attribute directly, '
'as the result will be cached and reused between requests. '
'Use `.all()` or call `.get_queryset()` instead.'
)
cls.queryset._fetch_all = force_evaluation
view = super(APIView, cls).as_view(**initkwargs)
view.cls = cls
view.initkwargs = initkwargs
# Note: session based authentication is explicitly CSRF validated,
# all other authentication is CSRF exempt.
return csrf_exempt(view)
@property
def allowed_methods(self):
"""
Wrap Django's private `_allowed_methods` interface in a public property.
"""
return self._allowed_methods()
@property
def default_response_headers(self):
headers = {
'Allow': ', '.join(self.allowed_methods),
}
if len(self.renderer_classes) > 1:
headers['Vary'] = 'Accept'
return headers
def http_method_not_allowed(self, request, *args, **kwargs):
"""
If `request.method` does not correspond to a handler method,
determine what kind of exception to raise.
"""
raise exceptions.MethodNotAllowed(request.method)
def permission_denied(self, request, message=None):
"""
If request is not permitted, determine what kind of exception to raise.
"""
if request.authenticators and not request.successful_authenticator:
raise exceptions.NotAuthenticated()
raise exceptions.PermissionDenied(detail=message)
def throttled(self, request, wait):
"""
If request is throttled, determine what kind of exception to raise.
"""
raise exceptions.Throttled(wait)
def get_authenticate_header(self, request):
"""
If a request is unauthenticated, determine the WWW-Authenticate
header to use for 401 responses, if any.
"""
authenticators = self.get_authenticators()
if authenticators:
return authenticators[0].authenticate_header(request)
def get_parser_context(self, http_request):
"""
Returns a dict that is passed through to Parser.parse(),
as the `parser_context` keyword argument.
"""
# Note: Additionally `request` and `encoding` will also be added
# to the context by the Request object.
return {
'view': self,
'args': getattr(self, 'args', ()),
'kwargs': getattr(self, 'kwargs', {})
}
def get_renderer_context(self):
"""
Returns a dict that is passed through to Renderer.render(),
as the `renderer_context` keyword argument.
"""
# Note: Additionally 'response' will also be added to the context,
# by the Response object.
return {
'view': self,
'args': getattr(self, 'args', ()),
'kwargs': getattr(self, 'kwargs', {}),
'request': getattr(self, 'request', None)
}
def get_exception_handler_context(self):
"""
Returns a dict that is passed through to EXCEPTION_HANDLER,
as the `context` argument.
"""
return {
'view': self,
'args': getattr(self, 'args', ()),
'kwargs': getattr(self, 'kwargs', {}),
'request': getattr(self, 'request', None)
}
def get_view_name(self):
"""
Return the view name, as used in OPTIONS responses and in the
browsable API.
"""
func = self.settings.VIEW_NAME_FUNCTION
return func(self.__class__, getattr(self, 'suffix', None))
def get_view_description(self, html=False):
"""
Return some descriptive text for the view, as used in OPTIONS responses
and in the browsable API.
"""
func = self.settings.VIEW_DESCRIPTION_FUNCTION
return func(self.__class__, html)
# API policy instantiation methods
def get_format_suffix(self, **kwargs):
"""
Determine if the request includes a '.json' style format suffix
"""
if self.settings.FORMAT_SUFFIX_KWARG:
return kwargs.get(self.settings.FORMAT_SUFFIX_KWARG)
def get_renderers(self):
"""
Instantiates and returns the list of renderers that this view can use.
"""
return [renderer() for renderer in self.renderer_classes]
def get_parsers(self):
"""
Instantiates and returns the list of parsers that this view can use.
"""
return [parser() for parser in self.parser_classes]
def get_authenticators(self):
"""
Instantiates and returns the list of authenticators that this view can use.
"""
return [auth() for auth in self.authentication_classes]
def get_permissions(self):
"""
Instantiates and returns the list of permissions that this view requires.
"""
return [permission() for permission in self.permission_classes]
def get_throttles(self):
"""
Instantiates and returns the list of throttles that this view uses.
"""
return [throttle() for throttle in self.throttle_classes]
def get_content_negotiator(self):
"""
Instantiate and return the content negotiation class to use.
"""
if not getattr(self, '_negotiator', None):
self._negotiator = self.content_negotiation_class()
return self._negotiator
def get_exception_handler(self):
"""
Returns the exception handler that this view uses.
"""
return self.settings.EXCEPTION_HANDLER
# API policy implementation methods
def perform_content_negotiation(self, request, force=False):
"""
Determine which renderer and media type to use render the response.
"""
renderers = self.get_renderers()
conneg = self.get_content_negotiator()
try:
return conneg.select_renderer(request, renderers, self.format_kwarg)
except Exception:
if force:
return (renderers[0], renderers[0].media_type)
raise
def perform_authentication(self, request):
"""
Perform authentication on the incoming request.
Note that if you override this and simply 'pass', then authentication
will instead be performed lazily, the first time either
`request.user` or `request.auth` is accessed.
"""
request.user
def check_permissions(self, request):
"""
Check if the request should be permitted.
Raises an appropriate exception if the request is not permitted.
"""
for permission in self.get_permissions():
if not permission.has_permission(request, self):
self.permission_denied(
request, message=getattr(permission, 'message', None)
)
def check_object_permissions(self, request, obj):
"""
Check if the request should be permitted for a given object.
Raises an appropriate exception if the request is not permitted.
"""
for permission in self.get_permissions():
if not permission.has_object_permission(request, self, obj):
self.permission_denied(
request, message=getattr(permission, 'message', None)
)
def check_throttles(self, request):
"""
Check if request should be throttled.
Raises an appropriate exception if the request is throttled.
"""
for throttle in self.get_throttles():
if not throttle.allow_request(request, self):
self.throttled(request, throttle.wait())
def determine_version(self, request, *args, **kwargs):
"""
If versioning is being used, then determine any API version for the
incoming request. Returns a two-tuple of (version, versioning_scheme)
"""
if self.versioning_class is None:
return (None, None)
scheme = self.versioning_class()
return (scheme.determine_version(request, *args, **kwargs), scheme)
# Dispatch methods
def initialize_request(self, request, *args, **kwargs):
"""
Returns the initial request object.
"""
parser_context = self.get_parser_context(request)
return Request(
request,
parsers=self.get_parsers(),
authenticators=self.get_authenticators(),
negotiator=self.get_content_negotiator(),
parser_context=parser_context
)
def initial(self, request, *args, **kwargs):
"""
Runs anything that needs to occur prior to calling the method handler.
"""
self.format_kwarg = self.get_format_suffix(**kwargs)
# Perform content negotiation and store the accepted info on the request
neg = self.perform_content_negotiation(request)
request.accepted_renderer, request.accepted_media_type = neg
# Determine the API version, if versioning is in use.
version, scheme = self.determine_version(request, *args, **kwargs)
request.version, request.versioning_scheme = version, scheme
# Ensure that the incoming request is permitted
self.perform_authentication(request)
self.check_permissions(request)
self.check_throttles(request)
def finalize_response(self, request, response, *args, **kwargs):
"""
Returns the final response object.
"""
# Make the error obvious if a proper response is not returned
assert isinstance(response, HttpResponseBase), (
'Expected a `Response`, `HttpResponse` or `HttpStreamingResponse` '
'to be returned from the view, but received a `%s`'
% type(response)
)
if isinstance(response, Response):
if not getattr(request, 'accepted_renderer', None):
neg = self.perform_content_negotiation(request, force=True)
request.accepted_renderer, request.accepted_media_type = neg
response.accepted_renderer = request.accepted_renderer
response.accepted_media_type = request.accepted_media_type
response.renderer_context = self.get_renderer_context()
# Add new vary headers to the response instead of overwriting.
vary_headers = self.headers.pop('Vary', None)
if vary_headers is not None:
patch_vary_headers(response, cc_delim_re.split(vary_headers))
for key, value in self.headers.items():
response[key] = value
return response
def handle_exception(self, exc):
"""
Handle any exception that occurs, by returning an appropriate response,
or re-raising the error.
"""
if isinstance(exc, (exceptions.NotAuthenticated,
exceptions.AuthenticationFailed)):
# WWW-Authenticate header for 401 responses, else coerce to 403
auth_header = self.get_authenticate_header(self.request)
if auth_header:
exc.auth_header = auth_header
else:
exc.status_code = status.HTTP_403_FORBIDDEN
exception_handler = self.get_exception_handler()
context = self.get_exception_handler_context()
response = exception_handler(exc, context)
if response is None:
self.raise_uncaught_exception(exc)
response.exception = True
return response
def raise_uncaught_exception(self, exc):
if settings.DEBUG:
request = self.request
renderer_format = getattr(request.accepted_renderer, 'format')
use_plaintext_traceback = renderer_format not in ('html', 'api', 'admin')
request.force_plaintext_errors(use_plaintext_traceback)
raise
# Note: Views are made CSRF exempt from within `as_view` as to prevent
# accidental removal of this exemption in cases where `dispatch` needs to
# be overridden.
def dispatch(self, request, *args, **kwargs):
"""
`.dispatch()` is pretty much the same as Django's regular dispatch,
but with extra hooks for startup, finalize, and exception handling.
"""
self.args = args
self.kwargs = kwargs
# ####################### 第一步 request二次封裝 #######################
"""
return Request(
request,
parsers=self.get_parsers(), 解析相關 對象清單
authenticators=self.get_authenticators(), 認證相關 對象清單
negotiator=self.get_content_negotiator(), 選擇相關 選擇對象
parser_context=parser_context 解析内容
)
"""
request = self.initialize_request(request, *args, **kwargs)
self.request = request
self.headers = self.default_response_headers # deprecate?
# ####################### 第二步 初始化 #######################
"""
2.1 擷取版本
傳回(scheme.determine_version(request, *args, **kwargs), scheme)
request.version, request.versioning_scheme =版本号，檢查版本的對象
2.2 認證
self.perform_authentication(request)
調用request.user方法
2.3 檢查權限
self.check_permissions(request)
擷取權限的對象清單
執行對象.has_permission方法 傳回True有權限，傳回False沒有權限，抛出異常，message定制錯誤資訊。
2.4 檢查限制通路
self.check_throttles(request)
擷取限制類的對象清單
執行對象.allow_request(request, self) 傳回True可以通路，傳回False限制通路。
"""
try:
self.initial(request, *args, **kwargs)
# ####################### 第三步 執行對應的視圖函數 #######################
# Get the appropriate handler method
if request.method.lower() in self.http_method_names:
handler = getattr(self, request.method.lower(),
self.http_method_not_allowed)
else:
handler = self.http_method_not_allowed
response = handler(request, *args, **kwargs)
except Exception as exc:
response = self.handle_exception(exc)
self.response = self.finalize_response(request, response, *args, **kwargs)
return self.response
def options(self, request, *args, **kwargs):
"""
Handler method for HTTP 'OPTIONS' request.
"""
if self.metadata_class is None:
return self.http_method_not_allowed(request, *args, **kwargs)
data = self.metadata_class().determine_metadata(request, self)
return Response(data, status=status.HTTP_200_OK) views.py
Django Rest Framework 的的請求生命周期如下：
HTTP請求 —> wsgi —> 中間件 —> 路由分發 —> 執行對應類的dispatch方法 —> 視圖函數 —>傳回
主要說dispatch中執行了哪些操作：
def dispatch(self, request, *args, **kwargs):
"""
`.dispatch()` is pretty much the same as Django's regular dispatch,
but with extra hooks for startup, finalize, and exception handling.
"""
self.args = args
self.kwargs = kwargs
# ####################### 第一步 request二次封裝 #######################
"""
return Request(
request,
parsers=self.get_parsers(), 解析相關 對象清單
authenticators=self.get_authenticators(), 認證相關 對象清單
negotiator=self.get_content_negotiator(), 選擇相關 選擇對象
parser_context=parser_context 解析内容
)
"""
request = self.initialize_request(request, *args, **kwargs)
self.request = request
self.headers = self.default_response_headers # deprecate?
# ####################### 第二步 初始化 #######################
"""
2.1 擷取版本
傳回(scheme.determine_version(request, *args, **kwargs), scheme)
request.version, request.versioning_scheme =版本号，檢查版本的對象
2.2 認證
self.perform_authentication(request)
調用request.user方法
2.3 檢查權限
self.check_permissions(request)
擷取權限的對象清單
執行對象.has_permission方法 傳回True有權限，傳回False沒有權限，抛出異常，message定制錯誤資訊。
2.4 檢查限制通路
self.check_throttles(request)
擷取限制類的對象清單
執行對象.allow_request(request, self) 傳回True可以通路，傳回False限制通路。
"""
try:
self.initial(request, *args, **kwargs)
# ####################### 第三步 執行對應的視圖函數 #######################
# Get the appropriate handler method
if request.method.lower() in self.http_method_names:
handler = getattr(self, request.method.lower(),
self.http_method_not_allowed)
else:
handler = self.http_method_not_allowed
response = handler(request, *args, **kwargs)
except Exception as exc:
response = self.handle_exception(exc)
self.response = self.finalize_response(request, response, *args, **kwargs)
return self.response