我使用下面的一組序列化程序來實現連接，該連接在我的開發設置中工作正常，但在網站服務器和數據庫服務器之間有任何距離時表現非常糟糕。我對運行這個節目的SQL有些懷疑，並做了一些日誌記錄;它似乎正在爲每個條目做一個新的查詢併合並結果，而不是一次完成整個連接並按照我的要求返回連接。這裏是我的串行：使用Django REST Framework序列化程序進行高效連接

class UserSerializer(serializers.ModelSerializer): 
    class Meta: 
     model = User 
     exclude = ('password', 'last_login', 'is_superuser', 'is_staff', 'is_active', 'date_joined', 
        'groups', 'user_permissions') 


class DepartmentSerializer(serializers.HyperlinkedModelSerializer): 
    curator = UserSerializer() 
    class Meta: 
     model = Department 
     fields = '__all__' 


class CategorySerializer(serializers.HyperlinkedModelSerializer): 
    class Meta: 
     model = Category 
     fields = '__all__' 


class DetailedLinkedContentSerializer(serializers.HyperlinkedModelSerializer): 
    category = CategorySerializer() 
    department = DepartmentSerializer() 
    type = serializers.SerializerMethodField() 

    class Meta: 
     fields = '__all__' 
     model = LinkedContent 

    def get_type(self, obj): 
     return 'link' 


class DetailedFileContentSerializer(serializers.HyperlinkedModelSerializer): 
    category = CategorySerializer() 
    department = DepartmentSerializer() 
    link_url = serializers.SerializerMethodField() 
    type = serializers.SerializerMethodField() 

    class Meta: 
     fields = '__all__' 
     model = FileContent 

    def get_link_url(self, obj): 
     return obj.file.url 

    def get_type(self, obj): 
     return obj.file_type

正如你所看到的，我做我的，包括串行領域其他車型的序列化，如類= CategorySerializer（）「加入」。它看起來像DRF recommends，除非我誤解了一些東西。這裏是成百上千查詢的一個小樣本正在對我的開發環境中運行：

(0.001) SELECT "content_linkedcontent"."id", "content_linkedcontent"."link_text", "content_linkedcontent"."department_id", "content_linkedcontent"."category_id", "content_linkedcontent"."visibility_rank", "content_linkedcontent"."link_url" FROM "content_linkedcontent"; args=() 
(0.001) SELECT "content_category"."id", "content_category"."name", "content_category"."description" FROM "content_category" WHERE "content_category"."id" = 3; args=(3,) 
(0.001) SELECT "content_department"."id", "content_department"."name", "content_department"."description", "content_department"."curator_id", "content_department"."visibility_rank" FROM "content_department" WHERE "content_department"."id" = 24; args=(24,) 
(0.000) SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login", "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user" WHERE "auth_user"."id" = 3; args=(3,) 
(0.000) SELECT "content_category"."id", "content_category"."name", "content_category"."description" FROM "content_category" WHERE "content_category"."id" = 3; args=(3,) 
(0.000) SELECT "content_department"."id", "content_department"."name", "content_department"."description", "content_department"."curator_id", "content_department"."visibility_rank" FROM "content_department" WHERE "content_department"."id" = 29; args=(29,) 
(0.000) SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login", "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user" WHERE "auth_user"."id" = 6; args=(6,) 
(0.000) SELECT "content_category"."id", "content_category"."name", "content_category"."description" FROM "content_category" WHERE "content_category"."id" = 4; args=(4,) 
(0.000) SELECT "content_department"."id", "content_department"."name", "content_department"."description", "content_department"."curator_id", "content_department"."visibility_rank" FROM "content_department" WHERE "content_department"."id" = 25; args=(25,) 
(0.000) SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login", "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user" WHERE "auth_user"."id" = 6; args=(6,) 
(0.000) SELECT "content_category"."id", "content_category"."name", "content_category"."description" FROM "content_category" WHERE "content_category"."id" = 1; args=(1,) 
(0.000) SELECT "content_department"."id", "content_department"."name", "content_department"."description", "content_department"."curator_id", "content_department"."visibility_rank" FROM "content_department" WHERE "content_department"."id" = 29; args=(29,) 
(0.000) SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login", "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user" WHERE "auth_user"."id" = 6; args=(6,) 
(0.000) SELECT "content_category"."id", "content_category"."name", "content_category"."description" FROM "content_category" WHERE "content_category"."id" = 1; args=(1,) 
(0.000) SELECT "content_department"."id", "content_department"."name", "content_department"."description", "content_department"."curator_id", "content_department"."visibility_rank" FROM "content_department" WHERE "content_department"."id" = 25; args=(25,) 
(0.000) SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login", "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user" WHERE "auth_user"."id" = 6; args=(6,) 
(0.000) SELECT "content_category"."id", "content_category"."name", "content_category"."description" FROM "content_category" WHERE "content_category"."id" = 1; args=(1,) 
(0.000) SELECT "content_department"."id", "content_department"."name", "content_department"."description", "content_department"."curator_id", "content_department"."visibility_rank" FROM "content_department" WHERE "content_department"."id" = 24; args=(24,) 
(0.000) SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login", "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user" WHERE "auth_user"."id" = 3; args=(3,) 
(0.000) SELECT "content_category"."id", "content_category"."name", "content_category"."description" FROM "content_category" WHERE "content_category"."id" = 3; args=(3,) 
(0.000) SELECT "content_department"."id", "content_department"."name", "content_department"."description", "content_department"."curator_id", "content_department"."visibility_rank" FROM "content_department" WHERE "content_department"."id" = 28; args=(28,) 
(0.000) SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login", "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user" WHERE "auth_user"."id" = 6; args=(6,) 
(0.000) SELECT "content_category"."id", "content_category"."name", "content_category"."description" FROM "content_category" WHERE "content_category"."id" = 1; args=(1,) 
(0.000) SELECT "content_department"."id", "content_department"."name", "content_department"."description", "content_department"."curator_id", "content_department"."visibility_rank" FROM "content_department" WHERE "content_department"."id" = 28; args=(28,) 
(0.000) SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login", "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user" WHERE "auth_user"."id" = 6; args=(6,) 
(0.000) SELECT "content_category"."id", "content_category"."name", "content_category"."description" FROM "content_category" WHERE "content_category"."id" = 4; args=(4,)

那麼，如何做一個真正的與我想在DRF使用串行信息加入？

UPDATE：

我有管理由以下的this博客條目的建議削減一半查詢的時候，這裏是使用他們我的更新序列化和視圖：

class DetailedLinkedContentSerializer(serializers.HyperlinkedModelSerializer): 
    category = CategorySerializer() 
    department_query = Department.objects.all() 
    department_query = DepartmentSerializer.setup_eager_loading(department_query) 
    department = DepartmentSerializer(department_query) 
    # department = DepartmentSerializer() 
    type = serializers.SerializerMethodField() 

    class Meta: 
     fields = '__all__' 
     model = LinkedContent 

    def get_type(self, obj): 
     return 'link' 

    @staticmethod 
    def setup_eager_loading(queryset): 
     """ Perform necessary eager loading of data. """ 
     queryset = queryset.select_related('category', 'department') 
     return queryset 


class DetailedFileContentSerializer(serializers.HyperlinkedModelSerializer): 
    category = CategorySerializer() 
    department_query = Department.objects.all() 
    department_query = DepartmentSerializer.setup_eager_loading(department_query) 
    department = DepartmentSerializer(department_query) 
    # department = DepartmentSerializer() 
    link_url = serializers.SerializerMethodField() 
    type = serializers.SerializerMethodField() 

    class Meta: 
     fields = '__all__' 
     model = FileContent 

    def get_link_url(self, obj): 
     return obj.file.url 

    def get_type(self, obj): 
     return obj.file_type 

    @staticmethod 
    def setup_eager_loading(queryset): 
     """ Perform necessary eager loading of data. """ 
     queryset = queryset.select_related('category', 'department') 
     return queryset

和我查看使用這些序列化程序：

class DetailedContentView(views.APIView): 
    permission_classes = [IsAuthenticated, ContentCuratorOrReadOnly, IsGroupMember, ] 
    def get(self, request, *args, **kwargs): 
     context = {"request": request} 
     linked_content = LinkedContent.objects.all() 
     file_content = FileContent.objects.all() 
     # this line is newly added 
     linked_content = DetailedLinkedContentSerializer.setup_eager_loading(linked_content) 
     # this line too 
     file_content = DetailedLinkedContentSerializer.setup_eager_loading(file_content) 
     linked_content_serializer = DetailedLinkedContentSerializer(linked_content, many=True, context=context) 
     file_content_serializer = DetailedFileContentSerializer(file_content, many=True, context=context) 

     response = linked_content_serializer.data + file_content_serializer.data 
     response = sorted(response, key=lambda x: (x['department']['visibility_rank'], x['visibility_rank'])) 

     return Response(response)

但是，我的解決方案預取我的部門序列化程序中的用戶序列化程序似乎並沒有做的伎倆。具體來說，更新我的部門序列化後：

class DepartmentSerializer(serializers.HyperlinkedModelSerializer): 
    curator = UserSerializer() 
    class Meta: 
     model = Department 
     fields = '__all__' 

    @staticmethod 
    def setup_eager_loading(queryset): 
     """ Perform necessary eager loading of data. """ 
     queryset = queryset.select_related('curator') 
     return queryset

下面幾行：

department_query = Department.objects.all() 
department_query = DepartmentSerializer.setup_eager_loading(department_query) 
department = DepartmentSerializer(department_query)

似乎並沒有被預取我的策展人，因爲我想要的。

來源

2017-06-20 DragonBobZ

您是否嘗試過使用[select_related]（https://docs.djangoproject.com/en/1.11/ref/models/querysets/#select-related）或[prefetch_related]（https://docs.djangoproject.com /en/1.11/ref/models/querysets/#prefetch-related）在您的視圖中的查詢集？這些應該預加載數據，避免每個條目和每個關係的新請求。 –

我現在正在處理這個問題，而且我即將更新我的問題。 – DragonBobZ

我使用一個混合從this blog發現評論更新我的串行：

class EagerLoadingMixin: 
    @classmethod 
    def setup_eager_loading(cls, queryset): 
     if hasattr(cls, "_SELECT_RELATED_FIELDS"): 
      queryset = queryset.select_related(*cls._SELECT_RELATED_FIELDS) 
     if hasattr(cls, "_PREFETCH_RELATED_FIELDS"): 
      queryset = queryset.prefetch_related(*cls._PREFETCH_RELATED_FIELDS) 
     return queryset

，並添加'department__curator'到我的預取字段列表。現在看起來像這樣：

class DetailedFileContentSerializer(EagerLoadingMixin, serializers.HyperlinkedModelSerializer): 
    category = CategorySerializer() 
    department = DepartmentSerializer() 
    link_url = serializers.SerializerMethodField() 
    type = serializers.SerializerMethodField() 

    class Meta: 
     fields = '__all__' 
     model = FileContent 

    def get_link_url(self, obj): 
     return obj.file.url 

    def get_type(self, obj): 
     return obj.file_type 

    _SELECT_RELATED_FIELDS = ['department', 'category', 'department__curator']

該查詢現在大約需要1/3的時間並且不包含數百個SELECT。它仍然需要很長時間，但我相信我可以通過更改切換到我的數據庫的其他託管解決方案來解決這個問題。

來源

2017-06-20 23:22:12 DragonBobZ

使用Django REST Framework序列化程序進行高效連接

UPDATE：

回答

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