模型对应关系
文档将对模型的对应关系一对一、一对多、多对多的关系进行实例分析介绍
- 1:1 OneToOneFileld
- 1:N ForeignKey
- M:N ManyToManyField
模型
#创建班级表（）
class Grade(models.Model):
g_name = models.CharField(max_length=10)
#表名(不设置表名默认是：应用名_类名，app_grade,数据库名自动小写没有大写)
class Meta:
db_table = 'grade'
#创建一个学生表(学生与班级是一对多)
class Student(models.Model):
s_name = models.CharField(max_length=20,unique=True)
s_age = models.IntegerField(default=16)
s_sex = models.BooleanField(default=1)
#学生表与班级是一对多
g = models.ForeignKey(Grade,null=True)
#表名
class Meta:
db_table = 'student'
#创建一个学生信息表（学生信息与学生是一对一）
class StudentInfo(models.Model):
adderss = models.CharField(max_length=20,null=True)
phone = models.IntegerField(null=True)
#学生信息表与学生表一对一
stu = models.OneToOneField(Student)
#表名
class Meta:
db_table = 'StudentInfo'
#创建一个课程信息表（课程与学生是多对多）
class Coures(models.Model):
c_name = models.CharField(max_length=10)
#课程表与学生表是多对多
stu = models.ManyToManyField(Student)
#表名
class Meta:
db_table = 'course'
- 上面的代码我们创建了一对一、一对多、多对多，从以上的例子中出发去了解他们之间的关系
- 建立好模型在对应的python环境下进行迁移生成数据库，并手动添加数据
- 一对一即学生与学生信息
#在视图中添加学生数据
def addStu(request) :
if request.method == 'GET':
Student.objects.create(s_name='妲己', s_age=20, s_sex=False)
return HttpResponse('创建成功')
#在视图中删除学生信息
def delStu(request):
if request.method == 'GET':
stu = Student.objects.filter(id=13)
stu.delete()
return HttpResponse("删除成功")
#找到对应信息
def oneToOneStu(request):
if request.method == 'GET':
#在学生模型中找到学生对象
stu = Student.objects.get(id=1)
#通过学生对象找一对一关联表信息
#使用学生对象.学生信息表名(小写)获得信息表对象
stuinfo = stu.studentinfo
return HttpResponse(stuinfo)
#通过拓展表找学生信息
stuinfo = StudentInfo.objects.get(phone=123232321)
#使用学生信息表对象.学生信息表OneToOneField的字段名获得信息对应学生对
stu = stuinfo.stu
return HttpResponse(stuinfo)
#修改信息就是找到对应的信息直接通过点语法修改即可
def alteroneToOneStu(request)
if request.method == 'GET' :
#在学生模型中找到学生对象
stu = Student.objects.get(id=1)
#修改学生表中信息
stu.s_name = '新的名字'
#修改信息需要进行保存
stuinfo.save()
#修改这名学生的学生信息表中的信息
stuinfo = stu.studentinfo
stuinfo.adders = '新的地址'
#修改信息需要进行保存
stuinfo.save()
- 一对多即学生与班级
def OneToManyStu(request):
if request.method == 'GET':
#查询id=1的学生的班级名称
stu = Student.objects.get(id=1)
#拿到学生对象.ForeignKey字段名获得对应的班级对象
stug = stu.g
gname = stug.g_name
return HttpResponse([stug])
#id为1的班级的所有学生(filter拿到的是列表)
grade = Grade.objects.filter(id=1)[0]
#在涉及到设定关系字段的一方时，调用方法时需要使用_set来调用
stus = grade.student_set.all()
- 多对多即学生与课程
#添加课程
def addCoure(request):
if request.method == 'GET':
courses = ['高数','计算机网络']
for coure in courses:
Coures.objects.create(c_name=coure)
return HttpResponse('添加成功')
#给学生添加课程
def ManyToSelect(request):
if request.method == 'GET':
#拿到学生
stu = Student.objects.get(id=1)
#拿到课程c1
c1 = Coures.objects.get(id=1)
#拿到课程c2
c2 = Coures.objects.get(id=2)
#涉及了ManyToManyFiel在课程表中。为学生添加c1,c2时.课程要使用_set
stu.coures_set.add(c1)
stu.coures_set.add(c2)
#给课程添加学生
def ManyToSelect(request):
if request.method == 'GET':
#拿到学生
stu = Student.objects.get(id=1)
#拿到课程c1
c1 = Coures.objects.get(c_name='计算机网络')
#拿到课程c2
c2 = Course.objects.get(c_name='数学')
#给课程添加学生()
c1.courses.add(stu)
c2.courses.add(stu)
- 总结
一对第一
class B():
id = models.autoFiled(primary_key=True)
class A():
b = models.OneToOneField(B)
有A的对象，查询B
a = A()
b= a.b
b_id = a.b_id
有B的对象，反查A
b = B()
a = b.a
4. 一对多
class B():
id = models.autoFiled(primary_key=True)
class A():
b = models.ForeignKey(B)
一对多和一对一的关系： 一对多中外键是唯一的，那就成了一对一
有A的对象，查询B
a = A()
b =a.b
有B的对象，反查A
b = B()
a = b.a_set.all()
5. 多对多
class B():
id = models.autoFiled(primary_key=True)
class A():
b = models.ManyToManyField(B)
生成的表有三张，A表，B表，A_B表(迁移数据库自动生成)
有A的对象，查询B
a = A()
b =a.b
有B的对象，反查A
b = B()
a = b.a_set.all()
插入数据
a = A.objects.get(pk=1)
b = B.objects.get(pk=1)
a.b.add(b)
b.a_set.add(a)
删除数据
b.a_set.remove(a)
- 多对多练习
- 模型
from django.db import models
# Create your models here.
class Author(models.Model):
a_name = models.CharField(max_length=20)
a_age = models.IntegerField(null=True)
a_sex = models.BooleanField(default=True)
a_address = models.CharField(max_length=20)
class Meta:
db_table = 'author'
class Book(models.Model):
b_name = models.CharField(max_length=20)
b_type = models.CharField(max_length=10)
b_lenght = models.IntegerField(default=10000, null=True)
author = models.ManyToManyField(Author)
class Meta:
db_table = 'book'
- 视图
from django.shortcuts import render
from django.http import HttpResponse
from app2.models import Author
from app2.models import Book
def bookadd(request):
if request.method == 'GET':
# 创建书籍
Book.objects.create(b_name='白夜追凶', b_type='悬疑', b_lenght=100000)
Book.objects.create(b_name='斗罗大陆', b_type='玄幻', b_lenght=2000000)
Book.objects.create(b_name='斗破苍穹', b_type='玄幻', b_lenght=2000000)
Book.objects.create(b_name='盗墓笔记', b_type='悬疑', b_lenght=1500000)
Book.objects.create(b_name='红楼梦', b_type='古典小说', b_lenght=1200000)
return HttpResponse('创建书籍成功')
def authoradd(request):
if request.method == 'GET':
# 创建作者
Author.objects.create(a_name='指纹', a_address='南京', a_age=43)
Author.objects.create(a_name='唐家三少', a_address='北京', a_age=34)
Author.objects.create(a_name='天蚕土豆', a_address='四川', a_age=31)
Author.objects.create(a_name='南派三叔', a_address='浙江', a_age=45)
Author.objects.create(a_name='曹雪芹', a_address='辽岭', a_age=48)
Author.objects.create(a_name='高鹗', a_address='辽宁', a_age=57)
return HttpResponse('创建作者成功')
def author_book_add(request):
if request.method == 'GET':
# 给书籍添加作者
books = Book.objects.get(b_name='白夜追凶')
authors = Author.objects.get(a_name='指纹')
authors.book_set.add(books)
books = Book.objects.get(b_name='斗罗大陆')
authors = Author.objects.get(a_name='唐家三少')
authors.book_set.add(books)
books = Book.objects.get(b_name='斗破苍穹')
authors = Author.objects.get(a_name='天蚕土豆')
authors.book_set.add(books)
books = Book.objects.get(b_name='盗墓笔记')
authors = Author.objects.get(a_name='南派三叔')
authors.book_set.add(books)
books = Book.objects.get(b_name='红楼梦')
authors = Author.objects.get(a_name='曹雪芹')
authors.book_set.add(books)
books = Book.objects.get(b_name='红楼梦')
authors = Author.objects.get(a_name='高鹗')
authors.book_set.add(books)
return HttpResponse('给书籍添加作者成功')
def book_author_add(request):
if request.method == 'GET':
# 给书籍添加作者
books = Book.objects.get(b_name='白夜追凶')
authors = Author.objects.get(a_name='指纹')
books.author.add(authors)
books = Book.objects.get(b_name='斗罗大陆')
authors = Author.objects.get(a_name='唐家三少')
books.author.add(authors)
books = Book.objects.get(b_name='斗破苍穹')
authors = Author.objects.get(a_name='天蚕土豆')
books.author.add(authors)
books = Book.objects.get(b_name='盗墓笔记')
authors = Author.objects.get(a_name='南派三叔')
books.author.add(authors)
books = Book.objects.get(b_name='红楼梦')
authors = Author.objects.get(a_name='曹雪芹')
books.author.add(authors)
books = Book.objects.get(b_name='红楼梦')
authors = Author.objects.get(a_name='高鹗')
books.author.add(authors)
return HttpResponse('给书籍添加作者成功')
def book_author_delete(request):
if request.method == 'GET':
# 删除书的作者
books = Book.objects.get(b_name='红楼梦')
author = Author.objects.get(a_name='高鹗')
books.author.remove(author)
return HttpResponse('删除书的作者')
#删除作者的书
author = Author.objects.get(a_name='南派三叔')
books = Book.objects.get(b_name='盗墓笔记')
author.book_set.remove(books)
return HttpResponse('删除作者的书')
def bookdelete(request):
if request.method == 'GET':
books = Book.objects.get(b_name='红楼梦')
books.delete()
return HttpResponse('删除书')
def authordelete(request):
if request.method == 'GET':
author = Author.objects.get(a_name='南派三叔')
author.delete()
return HttpResponse('删除作者')
def book_author(request):
if request.method == 'GET':
#找到作者的书
authon = Author.objects.get(a_name='高鹗')
a = authon.book_set.all()
#找到书的作者
books = Book.objects.get(b_name='红楼梦')
a = books.author.filter()
return HttpResponse(a.values())