01 自定义filter

如果某个API需要传递一些条件进行搜索，其实就在是URL后面通过GET传参即可，例如：

/api/users?age=19&category=12

在drf中也有相应组件可以支持条件搜索。

# urls.py
from django.urls import path
from app01 import views
urlpatterns = [
    path('api/users/', views.UserView.as_view(
        {"get": "list", "post": "create"}
    )),
    path('api/users/<int:pk>/', views.UserView.as_view(
        {"get": "retrieve", "put": "update", "patch": "partial_update", "delete": "destroy"}
    )),
]

# views.py
from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from rest_framework.filters import BaseFilterBackend
from app01 import models
class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)
    class Meta:
        model = models.UserInfo
        fields = ["username", "age", "email", "level_text", "extra"]
    def get_extra(self, obj):
        return 666
class Filter1(BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):
        age = request.query_params.get('age')
        if not age:
            return queryset
        return queryset.filter(age=age)
class Filter2(BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):
        user_id = request.query_params.get('id')
        if not user_id:
            return queryset
        return queryset.filter(id__gt=user_id)
class UserView(ModelViewSet):
    filter_backends = [Filter1, Filter2]
    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer
    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")