django-rest-framework學習之Relationships & Hyperlinked APIs--2017年4月17日至18日

 

Relationships & Hyperlinked APIs

 

參考連接：

http://www.weiguda.com/blog/23/

http://www.django-rest-framework.org/tutorial/5-relationships-and-hyperlinked-apis/

 

目前咱們API中的關係用primary keys展現，這部分咱們會經過hyperlinking提升咱們API的內聚性和擴展性

 

【1】給API的根節點傳建一個端點

在views.py中添加：

from rest_framework.decorators import api_view
from rest_framework.response import Response
#reverse函數返回徹底合格的URLs
from rest_framework.reverse import reverse
 
@api_view(['GET'])
def api_root(request,format=None):
    return Response({
        'users':reverse('user-list',request=request,format=format),
        'myLesson':reverse('myLesson-list',request=request,format=format)
    })

 

【2】爲highlighted建立一個端點

和其餘API不一樣的是，咱們不用JSON格式，而是用HTML展現，Rest framework提供了兩種風格的HTML Render，一個是使用模板，另外一個用pre_rendererd，這裏咱們使用第二個

由於咱們要返回的不是一個類，而是一個屬性，因此沒有咱們可以是用的具體的generic view，因此咱們用generics.GenericAPIView並本身建立get方法

 

在views.py中添加：

from rest_framework import renderers
 
class MyLessonHighlight(generics.GenericAPIView):
    queryset = MyLesson.objects.all()
    serializer_class = MyLessonSerializer
    renderer_classes = (renderers.StaticHTMLRenderer,)
    def get(self,request,*args,**kwargs):
        myLesson = self.get_object()
        return Response(myLesson.highlighted)

 

在mylesson中urls.py添加：

url(r'^$', views.api_root),
url(r'^myLesson/(?P<pk>[0-9]+)/highlight/$', views.MyLessonHighlight.as_view()),

 

【3】給API添加超連接

有不少方式能夠展現實體間的關係：primary keys, hyperlinking, unique identifying slug field, default string, 或者使兩個類繼承自一個母體

REST framework 提供了上述全部風格，在此case中咱們使用hyperlinked，使用HyperlinkedModelSerializer

HyperlinkedModelSerializer 和 ModelSerializer 的區別：沒有id，多了url，用HyperlinkedRelatedField代替PrimaryKeyRelatedField

 

所以咱們重寫serializers.py

from rest_framework import serializers
from myLesson.models import MyLesson
from django.contrib.auth.models import User
 
class MyLessonSerializer(serializers.HyperlinkedModelSerializer):
    owner = serializers.ReadOnlyField(source='owner.username')
    url = serializers.HyperlinkedIdentityField(view_name="myLesson-detail")
    highlight = serializers.HyperlinkedIdentityField(view_name='myLesson-highlight',format='html')
    class Meta:
        model = MyLesson
        fields = ('url','id','highlight','owner','title','code','linenos','language','style')
 
 
class UserSerializer(serializers.HyperlinkedModelSerializer):
#    myLesson = serializers.PrimaryKeyRelatedField(many=True,queryset=MyLesson.objects.all())
    myLesson = serializers.HyperlinkedRelatedField(many=True,view_name='myLesson-detail',read_only=True)
    class Meta:        model = User
        fields = ('url','id','username','myLesson')

 

【4】確認URL patterns已經被命名

 

修改myLesson/urls.py：

from django.conf.urls import url,include
from myLesson import views
from rest_framework.urlpatterns import format_suffix_patterns
 
urlpatterns = [
    url(r'^$',views.api_root),
    url(r'^users/$',views.UserList.as_view(),name='user-list'),
    url(r'^users/(?P<pk>[0-9]+)/$',views.UserDetail.as_view(),name='user-detail'),
    url(r'^myLesson/$',views.MyLessonList.as_view(),name='myLesson-list'),
    url(r'^myLesson/(?P<pk>[0-9]+)/$',views.MyLessonDetail.as_view(),name='myLesson-detail'),    url(r'^myLesson/(?P<pk>[0-9]+)/highlight/$',views.MyLessonHighlight.as_view(),name='myLesson-highlight'),]
 
urlpatterns = format_suffix_patterns(urlpatterns)

 

【5】添加分頁

若是數據庫中的數據達到必定程度, 那麼用戶使用api時可能會返回大量數據, 所以, 咱們最好使用分頁功能。

咱們可使用django-rest-framework自帶的設置選項, 使list自動使用分頁:

# myTest/settings.py
    REST_FRAMEWORK = {
        'PAGINATE_BY': 10
    }

【6】修改bug，按照官網文檔的代碼寫完運行調試，有bug，報錯

Could not resolve URL for hyperlinked relationship using view name "mylesson-detail". You may have failed to include the related model in your API, or incorrectly configured the lookup_field attribute on this field.

修改問題參考連接：http://stackoverflow.com/questions/20550598/django-rest-framework-could-not-resolve-url-for-hyperlinked-relationship-using

解決辦法：在MyLessonSerializer中添加url說明：

url = serializers.HyperlinkedIdentityField(view_name="myLesson-detail")