在Django中使用基於類的視圖(ClassView)，類中所定義的方法名稱與Http的請求方法相對應，才能基於路由將請求分發(dispatch)到ClassView中的方法進行處理，而Django REST framework中可以突破這一點，通過ViewSets可以實現自定義路由。
創建一個ViewSets
為get_stocks方法添加list_route裝飾器，url_path參數是暴露在外的接口名稱
class StockViewSet(viewsets.ModelViewSet):
queryset = AppStock.objects.all()
@list_route(url_path='getstocklist')
def get_stocks(self, request, *args, **kwargs):
'''獲取股票列表'''
return Response({'succss':True,'msg':'操作成功'})
來看一下list_route的定義：
def list_route(methods=None, **kwargs):
"""
Used to mark a method on a ViewSet that should be routed for list requests.
"""
methods = ['get'] if (methods is None) else methods
def decorator(func):
func.bind_to_methods = methods
func.detail = False
func.kwargs = kwargs
return func
return decorator
對於接口，一般有獲取列表頁和獲取詳情兩種形式。同樣的，還有detail_route裝飾器。list_route、detail_route的作用都是為方法添加了bind_to_methods、detail、kwargs屬性，唯一的區別是detail屬性值的不同
def detail_route(methods=None, **kwargs):
"""
Used to mark a method on a ViewSet that should be routed for detail requests.
"""
methods = ['get'] if (methods is None) else methods
def decorator(func):
func.bind_to_methods = methods
func.detail = True
func.kwargs = kwargs
return func
return decorator
注冊路由
router=DefaultRouter()
router.register(r'stock',StockViewSet)
urlpatterns = [
url(r'',include(router.urls)),
url(r'^admin/', admin.site.urls),
]
自定義路由實現過程
DefaultRouter是BaseRouter的子類，register方法內部將其注冊的prefix與之對應的viewset保存在registry列表中
class BaseRouter(object):
def __init__(self):
self.registry = []
def register(self, prefix, viewset, base_name=None):
if base_name is None:
base_name = self.get_default_base_name(viewset)
self.registry.append((prefix, viewset, base_name))
其urls屬性是一個描述符，內部調用了get_urls方法
從get_routes中可以看出些眉目了，遍歷ViewSet中定義的方法，獲取到方法的bind_to_method和detail屬性（list_route、detail_route的功勞），根據detial屬性將它們分別保存到detail_routes和list_routes列表中，保存的是httpmethod與methodname的元祖對象
def get_routes(self, viewset):
"""
省略若干...
"""
# Determine any `@detail_route` or `@list_route` decorated methods on the viewset
detail_routes = []
list_routes = []
for methodname in dir(viewset):
attr = getattr(viewset, methodname)
httpmethods = getattr(attr, 'bind_to_methods', None)
detail = getattr(attr, 'detail', True)
httpmethods = [method.lower() for method in httpmethods]
if detail:
detail_routes.append((httpmethods, methodname))
else:
list_routes.append((httpmethods, methodname))
def _get_dynamic_routes(route, dynamic_routes):
ret = []
for httpmethods, methodname in dynamic_routes:
method_kwargs = getattr(viewset, methodname).kwargs
initkwargs = route.initkwargs.copy()
initkwargs.update(method_kwargs)
url_path = initkwargs.pop("url_path", None) or methodname
url_name = initkwargs.pop("url_name", None) or url_path
ret.append(Route(
url=replace_methodname(route.url, url_path),
mapping={httpmethod: methodname for httpmethod in httpmethods},
name=replace_methodname(route.name, url_name),
initkwargs=initkwargs,
))
return ret
ret = []
for route in self.routes:
if isinstance(route, DynamicDetailRoute):
# Dynamic detail routes (@detail_route decorator)
ret += _get_dynamic_routes(route, detail_routes)
elif isinstance(route, DynamicListRoute):
# Dynamic list routes (@list_route decorator)
ret += _get_dynamic_routes(route, list_routes)
else:
# Standard route
ret.append(route)
return ret
接着，遍歷routes列表，看到這個代碼，我也是看了挺久才看懂這用意，routes列表包含固定的四個Route對象
routes = [
# List route.
Route(
url=r'^{prefix}{trailing_slash}$',
mapping={
'get': 'list',
'post': 'create'
},
name='{basename}-list',
initkwargs={'suffix': 'List'}
),
# Dynamically generated list routes.
DynamicListRoute(
url=r'^{prefix}/{methodname}{trailing_slash}$',
name='{basename}-{methodnamehyphen}',
initkwargs={}
),
# Detail route.
Route(
url=r'^{prefix}/{lookup}{trailing_slash}$',
mapping={
'get': 'retrieve',
'put': 'update',
'patch': 'partial_update',
'delete': 'destroy'
},
name='{basename}-detail',
initkwargs={'suffix': 'Instance'}
),
# Dynamically generated detail routes.
DynamicDetailRoute(
url=r'^{prefix}/{lookup}/{methodname}{trailing_slash}$',
name='{basename}-{methodnamehyphen}',
initkwargs={}
),
]
其用意是通過調用_get_dynamic_routes內嵌方法，把routes列表中項作為模板，將list_routes和detail_routes中的項依次進行替換，最終得到一個Route對象的列表（Route是一個namedtuple，包含如url、mapping、name等項）
[
Route(url='^{prefix}{trailing_slash}$', mapping={'get': 'list', 'post': 'create'}, name='{basename}-list', initkwargs={'suffix': 'List'}),
Route(url='^{prefix}/getstocklist{trailing_slash}$', mapping={'get': 'get_stocks'}, name='{basename}-getstocklist', initkwargs={}),
Route(url='^{prefix}/{lookup}{trailing_slash}$', mapping={'get': 'retrieve', 'patch': 'partial_update', 'put': 'update', 'delete': 'destroy'}, name='{basename}-detail', initkwargs={'suffix': 'Instance'})
]
get_route方法的功能到此結束了，回到get_urls方法中
def get_urls(self):
"""
Use the registered viewsets to generate a list of URL patterns.
"""
ret = []
for prefix, viewset, basename in self.registry:
lookup = self.get_lookup_regex(viewset)
routes = self.get_routes(viewset)
for route in routes:
# Only actions which actually exist on the viewset will be bound
mapping = self.get_method_map(viewset, route.mapping)
if not mapping:
continue
# Build the url pattern
regex = route.url.format(
prefix=prefix,
lookup=lookup,
trailing_slash=self.trailing_slash
)
# If there is no prefix, the first part of the url is probably
# controlled by project's urls.py and the router is in an app,
# so a slash in the beginning will (A) cause Django to give
# warnings and (B) generate URLS that will require using '//'.
if not prefix and regex[:2] == '^/':
regex = '^' + regex[2:]
view = viewset.as_view(mapping, **route.initkwargs)
name = route.name.format(basename=basename)
ret.append(url(regex, view, name=name))
return ret
這里的核心點是viewset的as_view方法，是不是很熟悉，Django中基於類的視圖注冊路由時也是調用的ClassView的as_view方法。as_view方法是在父類ViewSetMixin中定義的，傳入的action參數是httpmethod與methodname的映射一個字典，如 {'get': 'get_stocks'}
def as_view(cls, actions=None, **initkwargs):
"""
省略若干...
"""
def view(request, *args, **kwargs):
self = cls(**initkwargs)
# We also store the mapping of request methods to actions,
# so that we can later set the action attribute.
# eg. `self.action = 'list'` on an incoming GET request.
self.action_map = actions
# Bind methods to actions
# This is the bit that's different to a standard view
for method, action in actions.items():
handler = getattr(self, action)
setattr(self, method, handler)
# And continue as usual
return self.dispatch(request, *args, **kwargs)
view.cls = cls
view.initkwargs = initkwargs
view.suffix = initkwargs.get('suffix', None)
view.actions = actions
return csrf_exempt(view)
核心點是這個view方法以及dispatch方法，view方法中遍歷anctions字典，通過setattr設置名稱為httpmethod的屬性，屬性值為methodname所對應的方法。在dispathch方法中，就可通過getattr獲取到httpmethod所對應的handler
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
request = self.initialize_request(request, *args, **kwargs)
self.request = request
self.headers = self.default_response_headers # deprecate?
try:
self.initial(request, *args, **kwargs)
# 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
get_urls方法最終返回的結果是url(regex, view, name=name)的列表，這也就是ViewSet幫我們創建的自定義路由，其實現與我們在urls.py注冊路由是一樣的。url方法得到的是RegexURLPattern對象
[
<RegexURLPattern appstock-list ^stock/$>,
<RegexURLPattern appstock-getstocklist ^stock/getstocklist/$>,
<RegexURLPattern appstock-detail ^stock/(?P<pk>[^/.]+)/$>
]
最后
訪問 http://127.0.0.1:8000/stock/getstocklist/，請求就會交由StockViewSet中的get_stocks方法進行處理了。
整個過程大致就是這樣了。