day94-1 模型补充---自关联

浅浅的花香味﹌ 2023-10-09 11:34 32阅读 0赞

*  模型补充
    
     *  自关联
        
         *  多对多关联
         *  一对多关联

# 模型补充 #

## 自关联 ##

1.  多对多关联
2.  一对多关联

### 多对多关联 ###

# models.py: class User(models.Model): name = models.CharField(max_length=32) gender_list = [ (1,'男'), (2,'女') ] gender = models.IntegerField(choices=gender_list, default=1) m = models.ManyToManyField('User') # 表结构 ''' app01_user： id name gender 1 leijun 1 2 haha 1 3 lala 2 4 zhenzhen 2 app01_user_m: id from_user_id to_user_id 1 1 4 2 2 3 3 2 4 ''' # user_m表中，两个字段，可以自己根据需求选择哪个是男哪个是女 # 这里我们把from_user_id当成boy，to_user_id当成girl

# views.py: #### 查询和haha约会的姑娘 def test2(request): res = models.User.objects.filter(name='haha', gender=1).first() print(res) # User object print(res.m) # app01.User.None objs = res.m.all() print(objs) # <QuerySet [<User: User object>, <User: User object>]>,返回两个对象，说明是girl对象 for obj in objs: print(obj.name) # lala,zhenzhen ''' 1. select * from app01_user_m where from_user_id = 2 ### to_user_id=[3,4]; 2. select * from app01_user where id in (3,4); ''' #### 查询和zhenzhen约会的男生 res = models.User.objects.filter(name='zhenzhen', gender=2).first() objs = res.user_set.all() # 返回男生对象 ''' 1. select * from app01_user_m where to_user_id = 4 ### from_user_id=[1,2] 2. select * from app01_user where id in (1,2) ''' for obj in objs: print(obj.name) # leijun,haha return HttpResponse('hello') # .m就是查from_user_id # user_set就是to_usre_id # 这里有些类似于正，反向查询，但并不是，因为并没有跨表

### 一对多关联 ###

# 表结构 # 类似BBS ''' 文章表 article： id title 1 xxxxx 2 llll 评论表comment： 回复评论的id id content article_id reply_id uid 1 xxx 1 0 1 2 kkkk 1 0 2 3 mmmm 1 0 3 4 bbbb 2 0 5 5 llll 1 1 6 bcjxzb 2 4 ''' # models class Article(models.Model): id = models.AutoField(primary_key=True) title = models.CharField(max_length=255, null=True) class Comment(models.Model): id = models.AutoField(primary_key=True) content = models.charField(max_length=255) article = models.ForeignKey("Article") reply = models.ForeignKey('Comment', default=0) # 自关联自己的id # 评论的结构 ''' xxx llll kkkk mmmm bbbb bcjxzb '''

转载于:https://www.cnblogs.com/lucky75/p/11373412.html