DRF的Filter元件

如果某個API需要傳遞一些條件進行搜尋，其實就在是URL後面通過GET傳參即可，例如：

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

在drf中filter元件可以支援條件搜尋。

1. 自定義filter

# models.py
from django.db import models


class Role(models.Model):
    """ 角色表 """
    title = models.CharField(verbose_name='名稱', max_length=32)


class Department(models.Model):
    """ 部門表 """
    title = models.CharField(verbose_name='名稱', max_length=32)


class UserInfo(models.Model):
    username = models.CharField(verbose_name='使用者名稱', max_length=32)
    age = models.CharField(verbose_name='年齡', max_length=32)
    level_choice = ((1, 'VIP'), (2, 'SVIP'), (3, 'PARTNER'))
    level = models.SmallIntegerField(verbose_name='級別', choices=level_choice)
    email = models.CharField(verbose_name='郵箱', max_length=32)

    # 建立外來鍵
    depart = models.ForeignKey(verbose_name="部門", to="Department", on_delete=models.CASCADE)

    # 多對多
    roles = models.ManyToManyField(verbose_name="角色", to="Role")

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

from api import models


# Create your views here.
class UserSerializer(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 '我是多餘的'


# 自定義Filter
class Filter1(BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):
        age = request.GET.get('age')  # 可以使用request.query_params
        if not age:
            return queryset
        return queryset.filter(age=age)


class Filter2(BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):
        id = request.query_params.get('id')
        if not id:
            return queryset
        return queryset.filter(id=id)


class UserView(ModelViewSet):
    filter_backends = [Filter1, Filter2]  # 加入需要傳遞的Filter
    queryset = models.UserInfo.objects.all()  # GenericAPIView這個類提供的變數
    serializer_class = UserSerializer

返回值:

原始碼流程

2. 第三方filter(常用)

在drf開發中有一個常用的第三方過濾器：DjangoFilterBackend。

pip install django-filter

註冊app：

INSTALLED_APPS = [
    ...
    'django_filters',
    ...
]

範例1: 簡單

檢視設定和應用：

# views.py
from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
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):
    filter_backends = [DjangoFilterBackend, ]
    filterset_fields = ["id", "age", "email"]

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：對請求的資料校驗成功後，執行儲存。"""
        serializer.save(depart_id=1, password="123")

範例2: 複雜

檢視設定和應用（範例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（必須的是存在的資料，否則報錯-->內部有校驗機制）
    # 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（自定義搜尋）
    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：對請求的資料校驗成功後，執行儲存。"""
        serializer.save(depart_id=1, password="123")

補充

lookup_expr有很多常見選擇：

'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'),

全域性設定和應用：

# settings.py 全域性設定

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

3. 內建filter

drf原始碼中內建了2個filter，分別是：

OrderingFilter，支援排序。

from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from app01 import models
from rest_framework.filters import OrderingFilter


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 UserView(ModelViewSet):
    filter_backends = [OrderingFilter, ]
    # ?order=id
    # ?order=-id
    # ?order=age
    ordering_fields = ["id", "age"]

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：對請求的資料校驗成功後，執行儲存。"""
        serializer.save(depart_id=1, password="123")

SearchFilter，支援模糊搜尋。

from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from app01 import models
from rest_framework.filters import SearchFilter


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 UserView(ModelViewSet):
    filter_backends = [SearchFilter, ]
    search_fields = ["id", "username", "age"]

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：對請求的資料校驗成功後，執行儲存。"""
        serializer.save(depart_id=1, password="123")

"app01_userinfo"."id" LIKE %18% ESCAPE '\' 
OR 
"app01_userinfo"."username" LIKE %18% ESCAPE '\' 
OR 
"app01_userinfo"."age" LIKE %18% ESCAPE '\'

DRF的filter元件