drf -- 过滤组件Filtering

对于列表数据可能需要根据字段进行过滤，我们可以通过添加django-fitlter扩展来增强支持。

• 安装：pip install django-filter
• 在配置文settings.py中增加过滤组件的设置：

INSTALLED_APPS = [
    ...
    'django_filters',  # 需要注册应用，
]

REST_FRAMEWORK = {
    ...
    # 全局配置，也可以使用局部配置
    'DEFAULT_FILTER_BACKENDS': ('django_filters.rest_framework.DjangoFilterBackend',)
}

示例1

• 进行简单的条件过滤

在视图类中添加 filter_fields类属性，指定可以过滤的字段

示例代码

from django_filters.rest_framework import DjangoFilterBackend
class StudentListView(ListAPIView):
    queryset = Student.objects.all()
    serializer_class = StudentSerializer
    filter_backends = [DjangoFilterBackend] #在视图中加上该类，就可以
    filter_fields = ['age', 'sex']

# 127.0.0.1:8000/opt/students/?sex=true  #单个过滤条件
# http://127.0.0.1:8000/opt/students/?sex=false&age=27 # 多个并列的过滤条件

示例2

• 较为复杂的过滤
• 通过导入过滤插件的类来自定义：from django_filters import FilterSet, filters
• 具体的过滤条件和字段，需要写入自己的定义的新类中，该类需继承FilterSet这个类，且视图类中需要用类变量filterset_class来接收自己定义的新类

示例代码：

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

#序列化类代码示例：
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


#自定义过滤类，代码示例：
class MyFilterSet(FilterSet):
    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"]


#视图函数代码示例:
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.定义更复杂的过滤条件

代码示例：

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

#过滤类代码：
#field_name：代表字段名称
#lookup_expr：代表次自动可以怎么进行过滤（比如，大于，小于，包含，in ，or等条件）
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")

4.常用的过滤条件(lookup_expr)

'exact': _(''), #全等于，不区分大小写
'iexact': _(''), #全等于，区分大小写

'contains': _('contains'), # 包含，不区分大小写
'icontains': _('contains'), #包含，区分大小写
'startswith': _('starts with'), #以....开头，不区分大小写
'istartswith': _('starts with'), #以....开头，区分大小写
'endswith': _('ends with'),  #以....结尾，不区分大小写
'iendswith': _('ends with'), #以....结尾，区分大小写
    
'gt': _('is greater than'), #大于 
'gte': _('is greater than or equal to'), #大于等于
'lt': _('is less than'), #小于
'lte': _('is less than or equal to'), #小于等于

'in': _('is in'), # 在 ... 中，
'range': _('is in range'),
'isnull': _(''), # 布尔值
    
'regex': _('matches regex'), #正则匹配，不常用，不区分大小写
'iregex': _('matches regex'),  #正则匹配，不常用，区分大小写