django上课笔记5-FK关联

一、FK关联

FK关联

    url.py里

        from app01 import views

        urlpatterns = [

            url(r'^admin/', admin.site.urls),

            url(r'^index.html$', views.index),

        ]

    views.py里

        from django.shortcuts import render,HttpResponse

        from app01 import models

        def index(request):

            zgl = models.UserInfo.objects.filter(username='zgl',gender=1).first()  # 拿到要查询的对象

            result = zgl.girls.all()  # 去U2U里拿到所有的b_id

            for u in result:

                print(u.g.nickname)   # 拿到b_id所对应的.g的女孩的nickname

            return HttpResponse('successfully done')

    models.py里

        from django.db import models

        class UserInfo(models.Model):

            nickname = models.CharField(max_length=16)

            username = models.CharField(max_length=16)

            passwd = models.CharField(max_length=64)

            gender_choice = (

                (1,'男'),

                (2,'女'),

            )

            gender= models.IntegerField(choices=gender_choice)

        # 反向查询时

        # related_query_name

        # obj对象男.U2U.girls_set.all()

        # obj对象女.U2U.boys_set.all()

        # related_name

        # obj对象男.girls.all()

        # obj对象女.boys.all()

        class U2U(models.Model):

            g = models.ForeignKey('UserInfo',related_name='boys')

            b = models.ForeignKey('UserInfo',related_name='girls')

    M2M自关联特性：

        models.py里

            from django.db import models

            class UserInfo(models.Model):

                nickname = models.CharField(max_length=16)

                username = models.CharField(max_length=16)

                passwd = models.CharField(max_length=64)

                gender_choice = (

                    (1,'男'),

                    (2,'女'),

                )

                gender= models.IntegerField(choices=gender_choice)

                m = models.ManyToManyField('UserInfo')  # 自己关联自己

        views.py里

            def index(request):

                #查女生

                girl = models.UserInfo.objects.filter(id=4,gender=2).first()  # 拿到要查询的对象

                result = girl.userinfo_set.all()

                for row in result:

                    print(row.nickname)

                return HttpResponse('successfully done')

        obj = models.UserInfo.objects.filter(id=1).first()

        # 对于from_userinfo_id 相当于正向查询通过.m的方式

        obj.m          => select xx from xx where from_userinfo_id = 1

        # 对于to_userinfo_id  相当于反向查询通过.userinfo_set的方式

        obj.userinfo_set => select xx from xx where to_userinfo_id = 1

    定义：

        # 前面列：男生ID

        # 后面列：女生ID

    应用：

        # 男生对象

        obj = models.UserInfo.objects.filter(id=1).first()

        # 根据男生ID=1查找关联的所有的女神

        obj.m.all()

        # 女生

        obj = models.UserInfo.objects.filter(id=4).first()

        # 根据女生ID=4查找关联的所有的男生

        obj.userinfo_set.all()

    问题:

    当打不开页面，发生404错误时

        url(r'^index.html$/', love.index) # index.html$后边不要加反斜杠