ORM-正向反向查询 · python-网页到放弃

[TOC] >[success] # 一、一对多利用ForeignKey 创建表注关联表中会自动添加字段后面加_id,相当于publish _id,其中单独的publish包含整个Publish对象 ~~~ class Book(models.Model): name = models.CharField(max_length=20) price = models.IntegerField() pud_data = models.DateField() publish = models.ForeignKey('Publish') class Publish(models.Model): name = models.CharField(max_length=32) city = models.CharField(max_length=32) ~~~ >[danger] ##### 增第一种方法通过真实的字段，也就是在_id添加 ~~~ def index(request): from cm import models obj = models.Book.objects.create( name = "c#", price = 200, pud_data = '2008-08-08', publish_id= 1 ) print(obj) return HttpResponse('ok') ~~~ 第二种通过对象添加，具体的操作是先查找出关联对象，把关联对象直接赋值給属性查正向查找通过对象包含查找 ~~~ def index(request): from cm import models obj = models.Book.objects.filter(name="python") print(obj[0].publish.city) return HttpResponse('ok') ~~~ * 反向查找,通过关联对象查找第一种通过对象反差 ~~~ def index(request): from cm import models obj = models.Publish.objects.filter(name="理工")[0] obj1 = models.Book.objects.filter(publish=obj).values("name") print(obj1) return HttpResponse('ok') ~~~ 第二种通过set反查,通过关联的类后面加_set ~~~ def index(request): from cm import models obj = models.Publish.objects.filter(name="理工")[0] obj1 = obj.book_set.all() print(obj1) return HttpResponse('ok') ~~~ 第三种直接属性双下滑下接字段，例如publish__name ~~~ def index(request): from cm import models obj = models.Book.objects.filter(publish__name="理工").values("name") print(obj) return HttpResponse('ok') ~~~ >[success] # 二、多对多利用ManyToManyField创建表 ~~~ class Book(models.Model): name = models.CharField(max_length=20) price = models.IntegerField() pud_data = models.DateField() authors = models.ManyToManyField('Author') class Author(models.Model): name = models.CharField(max_length=32) ~~~ >[danger] ##### 查利用查询包含ManyToManyField对象，进行查找关联表 ~~~ def index(request): from cm import models obj = models.Book.objects.filter(name="go") print(obj[0].authors.all().values('name')) return HttpResponse('ok') ~~~ 增加add,先找到关联对象，在有add添加对象 ~~~ def index(request): from cm import models obj = models.Author.objects.all() obj1 = models.Book.objects.filter(name="python") obj1[0].authors.add(*obj) return HttpResponse('ok') ~~~ 或者直接添加主键 ~~~ def index(request): from cm import models obj = [1,2] obj1 = models.Book.objects.filter(name="python") obj1[0].authors.add(*obj) return HttpResponse('ok') ~~~ remove删除 ~~~ def index(request): from cm import models obj = [1,] obj1 = models.Book.objects.filter(name="python") obj1[0].authors.remove(*obj) return HttpResponse('ok') ~~~