DRF源码解析3--routers对路由的封装

DRF

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 2020/02/20   Share

当我们想最方便的使用drf的路由的时候,只需要用DefaultRoute实例化一个路由实例,然后注册,再讲注册后的组件加入urlpatterns即可

from rest_framework.routers import DefaultRouter
router = DefaultRouter()
# 其中BookModelView继承了viewsets.ModelViewSet
router.register(r'^book', views.BookModelView)

urlpatterns += router.urls

到底routers底层是怎么样实现的呢

routers

DefaultRoute是routers组件里的一个类,相当于帮助我们在路由里构建好了如{‘list’:”create”}的对应关系,它继承了SimpleRouter,截取源码如下

class SimpleRouter(BaseRouter):
    routes = [
        # List route.
        Route(
            url=r'^{prefix}{trailing_slash}$',
			# 这里构建好了对应关系
            mapping={
                'get': 'list',
                'post': 'create'
            },
            name='{basename}-list',
            detail=False,
            initkwargs={'suffix': 'List'}
        ),

    def __init__(self, trailing_slash=True):
        self.trailing_slash = '/' if trailing_slash else ''
        super().__init__()

    def get_default_basename(self, viewset):
        """
        If `basename` is not specified, attempt to automatically determine
        it from the viewset.
        """
        queryset = getattr(viewset, 'queryset', None)

        assert queryset is not None, '`basename` argument not specified, and could ' \
            'not automatically determine the name from the viewset, as ' \
            'it does not have a `.queryset` attribute.'

        return queryset.model._meta.object_name.lower()

    def get_routes(self, viewset):
		# 获取对应关系
        known_actions = list(flatten([route.mapping.values() for route in self.routes if isinstance(route, Route)]))
		# 找出viewsets里所有的方法
        extra_actions = viewset.get_extra_actions()

        # checking action names against the known actions list
		# 判断路由的方法对应的viewsets的方法
        not_allowed = [
            action.__name__ for action in extra_actions
            if action.__name__ in known_actions
        ]
        if not_allowed:
            msg = ('Cannot use the @action decorator on the following '
                   'methods, as they are existing routes: %s')
            raise ImproperlyConfigured(msg % ', '.join(not_allowed))

        # partition detail and list actions
        detail_actions = [action for action in extra_actions if action.detail]
        list_actions = [action for action in extra_actions if not action.detail]

        routes = []
        for route in self.routes:
            if isinstance(route, DynamicRoute) and route.detail:
                routes += [self._get_dynamic_route(route, action) for action in detail_actions]
            elif isinstance(route, DynamicRoute) and not route.detail:
                routes += [self._get_dynamic_route(route, action) for action in list_actions]
            else:
                routes.append(route)

        return routes

    def get_urls(self):
        """
        Use the registered viewsets to generate a list of URL patterns.
        """
        ret = []
		# 这里的self.registry是父类BaseRouter的一个属性
        for prefix, viewset, basename in self.registry:
            lookup = self.get_lookup_regex(viewset)
            routes = self.get_routes(viewset)
		# 这里是对路径进行了不同形式的封装
            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 not prefix and regex[:2] == '^/':
                    regex = '^' + regex[2:]

                initkwargs = route.initkwargs.copy()
                initkwargs.update({
                    'basename': basename,
                    'detail': route.detail,
                })

                view = viewset.as_view(mapping, **initkwargs)
                name = route.name.format(basename=basename)
                ret.append(url(regex, view, name=name))

        return ret

进入BaseRouter中,截取源码如下:

class BaseRouter:
    def __init__(self):
		# SimpleRouter的get_urls中的需要的属性
        self.registry = []

    def register(self, prefix, viewset, basename=None):
		# 如果没有basename,则self.get_default_basename()方法
		# get_default_basename()方法就是报错要求basename必须有,
		# 从而看得出来要想使用router组件必须执行register()方法
        if basename is None:
            basename = self.get_default_basename(viewset)
        self.registry.append((prefix, viewset, basename))

        # invalidate the urls cache
        if hasattr(self, '_urls'):
            del self._urls

    def get_default_basename(self, viewset):
        """
        If `basename` is not specified, attempt to automatically determine
        it from the viewset.
        """
        raise NotImplementedError('get_default_basename must be overridden')

    def get_urls(self):
        """
        Return a list of URL patterns, given the registered viewsets.
        """
        raise NotImplementedError('get_urls must be overridden')

    @property
    def urls(self):
        if not hasattr(self, '_urls'):
            self._urls = self.get_urls()
        return self._urls

DefaultRoute类进行了更好的优化

class DefaultRouter(SimpleRouter):
    """
    The default router extends the SimpleRouter, but also adds in a default
    API root view, and adds format suffix patterns to the URLs.
    """
    include_root_view = True
    include_format_suffixes = True
    root_view_name = 'api-root'
    default_schema_renderers = None
    APIRootView = APIRootView
    APISchemaView = SchemaView
    SchemaGenerator = SchemaGenerator

    def __init__(self, *args, **kwargs):
        if 'root_renderers' in kwargs:
            self.root_renderers = kwargs.pop('root_renderers')
        else:
            self.root_renderers = list(api_settings.DEFAULT_RENDERER_CLASSES)
        super().__init__(*args, **kwargs)

    def get_api_root_view(self, api_urls=None):
        """
        Return a basic root view.
        """
        api_root_dict = OrderedDict()
        list_name = self.routes[0].name
        for prefix, viewset, basename in self.registry:
            api_root_dict[prefix] = list_name.format(basename=basename)

        return self.APIRootView.as_view(api_root_dict=api_root_dict)

    def get_urls(self):
        urls = super().get_urls()
        if self.include_root_view:
            view = self.get_api_root_view(api_urls=urls)
            root_url = url(r'^$', view, name=self.root_view_name)
            urls.append(root_url)

        if self.include_format_suffixes:
            urls = format_suffix_patterns(urls)

        return urls

最后路由组件创建了怎么样的url?

Author：liangweijiang

原文链接：https://liangweijiang.github.io/2020/02/20/DRF-03/

发表日期：February 20th 2020, 11:15:11 pm

更新日期：February 20th 2020, 11:16:50 pm

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