Django框架详细介绍---ORM---图书信息系统专题训练

from django.db import models

# Create your models here.
# 书
class Book(models.Model):
    title = models.CharField(max_length=32)
    publish_date = models.DateField(auto_now_add=True)
    price = models.DecimalField(max_digits=5, decimal_places=2)
    memo = models.TextField(null=True)
    # 创建外键，关联publish
    publisher = models.ForeignKey(to="Publisher", on_delete=models.CASCADE, related_name='books')
    # 创建多对多关联author
    author = models.ManyToManyField(to="Author")

    def __str__(self):
        return self.title

# 出版社
class Publisher(models.Model):
    name = models.CharField(max_length=32)
    city = models.CharField(max_length=32)

    def __str__(self):
        return self.name

# 作者
class Author(models.Model):
    name = models.CharField(max_length=32)
    age = models.IntegerField()
    phone = models.CharField(max_length=11)
    detail = models.OneToOneField(to="AuthorDetail", on_delete=models.CASCADE)

    def __str__(self):
        return self.name

# 作者详情
class AuthorDetail(models.Model):
    addr = models.CharField(max_length=64)
    email = models.EmailField()

表结构：

练习：

import os

if __name__ == "__main__":
    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite05.settings")

    import django
    django.setup()
    # 在设置好环境变量以及导入Django项目之后才能找到Django项目下的APP
    # 所以必须要在这里导入
    from app import models

    # 查找某个出版社关联的所有的书籍---反向查找
    # ret = models.Publisher.objects.get(id='2').book_set.all()

    # 在Book中添加反向操作related_name之后
    # ret = models.Publisher.objects.get(id='2').books.all()

    # 查找书名为七侠五义的出版社的名字
    # Book类和Publisher定义的时候调用了__str__方法
    # 实例化出类的时候自动打印出相应的名字
    # ret = models.Book.objects.get(title='七侠五义').publisher

    # 查找所有书名里有传奇的书
    # ret = models.Book.objects.filter(title__contains='传奇')

    # 查找出版日期为2017年的书籍
    # ret = models.Book.objects.filter(publish_date__year=2017)

    # 查找出版日期是2018年的书名
    # ret = models.Book.objects.filter(publish_date__year=2018).values('title')

    # 查找价格大于100元的书籍
    # ret = models.Book.objects.filter(price__gt=100).values("title", "price")

    # 查找某字段为空的
    # ret = models.Book.objects.filter(memo__isnull=True)

    # 查找在北京的出版社
    # ret = models.Publisher.objects.filter(city='北京')

    # 查找名字以传奇结尾的书本
    # ret = models.Book.objects.filter(title__endswith='传奇').values('title')

    # 查找作者名字里面带"张"字的作者
    # ret = models.Author.objects.filter(name__contains="张")

    # 查找年龄大于30岁的作者
    # ret = models.Author.objects.filter(age__gt=19)

    # 查找手机号是155开头的作者
    # ret = models.Author.objects.filter(phone__startswith='155')

    # 查找手机号是155开头的作者的姓名和年龄
    # ret = models.Author.objects.filter(phone__startswith='155').values('name','age')

    # 查找书名是"七侠五义"的书的出版社
    # 基于对象查找
    # ret = models.Book.objects.get(title="七侠五义").publisher

    # 查找书名是"武林传奇"的书的出版社所在的城市
    # ret = models.Book.objects.get(title="武林传奇").publisher.city
    # 基于双下滑线的查找方式
    # ret = models.Book.objects.filter(title="武林传奇").values("publisher__city")

    # 查找书名是"武林传奇"的书的出版社的名称
    # ret = models.Book.objects.filter(title="武林传奇").values("publisher__name")

    # 查找书名是"七侠五义"的书的所有作者
    # ret = models.Book.objects.filter(title='七侠五义').values('author__name').all()

    # 查找书名是"武林传奇"的书的作者的年龄
    # ret = models.Book.objects.filter(title='七侠五义').values('author__name','author__age').all()

    # 查找书名是"武林传奇"的书的作者的手机号码
    # ret = models.Book.objects.filter(title='武林传奇').values('author__name','author__phone')

    # 查找书名是"武林传奇"的书的作者的地址
    # ret = models.Book.objects.filter(title='武林传奇').values('author__detail__addr')

    # 查找书名是"武林传奇"的书的作者的邮箱
    # ret = models.Book.objects.filter(title='武林传奇').values('author__detail__email')

    # print(ret)

习题答案