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

1、自定义Filter

# 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

# 自定义Filter1
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)

# 自定义Filter2
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):
    # 设置
    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")

2、第三方Filter

在drf开发中有一个常用的第三方过滤器：DjangoFilterBackend。

# 1.安装
pip install django-filter

# 2.注册APP
INSTALLED_APPS = [
    ...
    'django_filters',
    ...
]

视图配置和应用（示例1）：

# views.py
from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet

# 引入第三方模块
from django_filters.rest_framework import DjangoFilterBackend
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 UserView(ModelViewSet):
    # 设置
    filter_backends = [DjangoFilterBackend, ]
    filterset_fields = ["id", "age", "email"]    # 可以通过url后的id、age等参数进行筛选

    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")

视图配置和应用（示例2）：

from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from django_filters.rest_framework import DjangoFilterBackend
from django_filters import FilterSet, filters
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    depart_title = serializers.CharField(
        source="depart.title",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["id", "username", "age", "email", "level_text", "extra", "depart_title"]

    def get_extra(self, obj):
        return 666


class MyFilterSet(FilterSet):
    # 可自定义参数，并设置参数大于、等于、包含等
    depart = filters.CharFilter(field_name="depart__title", lookup_expr="exact")
    min_id = filters.NumberFilter(field_name='id', lookup_expr='gte')

    class Meta:
        model = models.UserInfo
        fields = ["min_id", "depart"]


class UserView(ModelViewSet):
    filter_backends = [DjangoFilterBackend, ]
    filterset_class = MyFilterSet

    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")

视图配置和应用（示例3）：

from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from django_filters.rest_framework import DjangoFilterBackend, OrderingFilter
from django_filters import FilterSet, filters
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    depart_title = serializers.CharField(
        source="depart.title",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["id", "username", "age", "email", "level_text", "extra", "depart_title"]

    def get_extra(self, obj):
        return 666


class MyFilterSet(FilterSet):
    # /api/users/?min_id=2  -> id>=2
    min_id = filters.NumberFilter(field_name='id', lookup_expr='gte')

    # /api/users/?name=wupeiqi  -> not ( username=wupeiqi )
    name = filters.CharFilter(field_name="username", lookup_expr="exact", exclude=True)

    # /api/users/?depart=xx     -> depart__title like %xx%
    depart = filters.CharFilter(field_name="depart__title", lookup_expr="contains")

    # /api/users/?token=true      -> "token" IS NULL
    # /api/users/?token=false     -> "token" IS NOT NULL
    token = filters.BooleanFilter(field_name="token", lookup_expr="isnull")

    # /api/users/?email=xx     -> email like xx%
    email = filters.CharFilter(field_name="email", lookup_expr="startswith")

    # /api/users/?level=2&level=1   -> "level" = 1 OR "level" = 2（必须的是存在的数据，否则报错-->内部有校验机制）
    # level = filters.AllValuesMultipleFilter(field_name="level", lookup_expr="exact")
    level = filters.MultipleChoiceFilter(field_name="level", lookup_expr="exact", choices=models.UserInfo.level_choices)

    # /api/users/?age=18,20     -> age in [18,20]
    age = filters.BaseInFilter(field_name='age', lookup_expr="in")

    # /api/users/?range_id_max=10&range_id_min=1    -> id BETWEEN 1 AND 10
    range_id = filters.NumericRangeFilter(field_name='id', lookup_expr='range')

    # /api/users/?ordering=id     -> order by id asc
    # /api/users/?ordering=-id     -> order by id desc
    # /api/users/?ordering=age     -> order by age asc
    # /api/users/?ordering=-age     -> order by age desc
    ordering = filters.OrderingFilter(fields=["id", "age"])

    # /api/users/?size=1     -> limit 1（自定义搜索）
    size = filters.CharFilter(method='filter_size', distinct=False, required=False)
    
    class Meta:
        model = models.UserInfo
        fields = ["id", "min_id", "name", "depart", "email", "level", "age", 'range_id', "size", "ordering"]

    def filter_size(self, queryset, name, value):
        int_value = int(value)
        return queryset[0:int_value]


class UserView(ModelViewSet):
    filter_backends = [DjangoFilterBackend, ]
    filterset_class = MyFilterSet

    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")

3、lookup_expr有很多常见选择：

'exact': _(''),
'iexact': _(''),

'contains': _('contains'),
'icontains': _('contains'),
'startswith': _('starts with'),
'istartswith': _('starts with'),
'endswith': _('ends with'),  
'iendswith': _('ends with'),
    
'gt': _('is greater than'),
'gte': _('is greater than or equal to'),
'lt': _('is less than'),
'lte': _('is less than or equal to'),

'in': _('is in'),
'range': _('is in range'),
'isnull': _(''),
    
'regex': _('matches regex'),
'iregex': _('matches regex'),

4、全局配置和应用

# settings.py 全局配置

REST_FRAMEWORK = {
    'DEFAULT_FILTER_BACKENDS': ['django_filters.rest_framework.DjangoFilterBackend',]
}