Django基础6
-
1.模板的继承(使用频率较高)
-
2.模板的导入
-
3.数据库正向与反向迁移
-
4.单表查询前期准备
-
5.django脚本环境
-
6.单表查询关键字
-
7.单表查询之神奇的双下线查询
- 8.多表查询之外键字段的增删改查
1.模板的继承(使用频率较高)
需求: 页面主体不变 部分区域变化
模板继承
1.需要现在母版中使用block提前划定区域
{% block 区域名称 %}
{% endblock %}2.在子版中先继承再局部替换
{% extends '母版.html' %}
{% block 区域名称 %}
{% endblock %}总结
母版一般情况下都应该至少含有三个区域
1.css区域
2.content区域
3.js区域补充{{ block.super }} 调用母版内容
2.模板的导入(了解)
{% include 'myform.html' %}
3.数据库正向与反向迁移
正向迁移(将django中的类导入到MySQL中变成表)
python3 manage.py makemigrations
python3 manage.py migrate反向迁移
inspectdb
4.单表查询预备知识
from django.db import models
# Create your models here.
class Books(models.Model):
title = models.CharField(max_length=32)
price = models.DecimalField(max_digits=8,decimal_places=2)
# 日期类型
publish_time = models.DateField(auto_now_add=True)
"""
auto_now:每次修改数据之后都会自动更新当前时间
auto_now_add:第一次创建数据的时候自动记录时间
"""
# publish_time = models.DateTimeField()
def __str__(self):
return self.title # 只能返回字符串类型的数据
class Book(models.Model):
title = models.CharField(max_length=32)
price = models.DecimalField(max_digits=8, decimal_places=2)
# 日期类型
publish_time = models.DateField(auto_now_add=True)
publish = models.ForeignKey(to='Publish')
authors = models.ManyToManyField(to='Author')
def __str__(self):
return self.title # 只能返回字符串类型的数据
class Publish(models.Model):
title = models.CharField(max_length=32)
addr = models.CharField(max_length=64)
def __str__(self):
return self.title
class Author(models.Model):
name = models.CharField(max_length=32)
age = models.IntegerField()
author_detail = models.OneToOneField(to='AuthorDetail')
def __str__(self):
return self.name
class AuthorDetail(models.Model):
phone = models.BigIntegerField()
addr = models.CharField(max_length=64)
def __str__(self):
return self.addr5.django脚本环境
django默认情况下是不允许单独使用某个功能部分(models.py)
解决方法：
1.要么自己新建一个py文件
2.要么使用自带的tests文件
import os
if __name__ == "__main__":
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day47.settings")
import django
django.setup()6.单表查询关键字
# 增 1.create()
# models.Books.objects.create(title='三国演义',price=456.23)
# models.Books.objects.create(title='水浒传',price=876.45)
# models.Books.objects.create(title='聊斋志异',price=123.69)
# models.Books.objects.create(title='草堂笔记',price=456.96)
# 查 2.all()
# res = models.Books.objects.all()
# print(res) # QuerySet对象
# print(res.query) # 只要是QuerySet对象就可以点query查看内部SQL语句
# 查 3.filter()
# res1 = models.Books.objects.filter() # pk特指当前表的主键字段
# print(res1) # QuerySet对象
# print(res1.query)
# print(res1.first()) # 获取列表中第一个数据对象
# print(res1.last()) # 获取列表中最后一个数据对象
# 4.values与5.values_list
# res2 = models.Books.objects.values('title','price')
# print(res2) # QuerySet对象 可以看成列表套字典
# print(res2.query)
# res3 = models.Books.objects.values_list('title','price')
# print(res3) # QuerySet对象 可以看成列表套元祖
# print(res3.query)
# 6.查 get() 不推荐使用
# res4 = models.Books.objects.get(pk=1)
# print(res4) # 数据对象
# res5 = models.Books.objects.get(pk=100)
# print(res5) # 数据对象
# res6 = models.Books.objects.filter(pk=100)
# print(res6) # 数据对象
# 7.取反 exclude()
# res7 = models.Books.objects.exclude(pk=1)
# print(res7) # QuerySet
# print(res7.query)
# 8.排序 order_by() 默认是升序(asc) 字段前面加负号降序(desc)
# res8 = models.Books.objects.order_by('price')
# res8 = models.Books.objects.order_by('-price')
# select * from books order by price desc,price asc;
# res8 = models.Books.objects.order_by('-price','price')
# print(res8) # QuerySet对象
# print(res8.query)
# 9.反转 reverse() 必须先有顺序才可以反转
# res9 = models.Books.objects.all()
# res9 = models.Books.objects.order_by('price').reverse()
# print(res9)
# 10.去重 distinct()
# res10 = models.Books.objects.all().distinct()
# res10 = models.Books.objects.values('title','price').distinct()
# print(res10)
# 11.计数 count()
# res11 = models.Books.objects.count()
# print(res11) # 6
# 12.判断是否有数据 exists()
# res12 = models.Books.objects.filter(pk=999).exists()
# print(res12) # False
# 13.update()
# 14.delete()7.单表查询之神奇的双下划线
# 查询筛选价格的书籍
# res = models.Books.objects.filter(price__gt=200)
# print(res)
# res1 = models.Books.objects.filter(price__lt=200)
# print(res1)
# res2 = models.Books.objects.filter(price__gte=456.23)
# print(res2)
# res3 = models.Books.objects.filter(price__lte=456.23)
# print(res3)
# 成员运算
# res4 = models.Books.objects.filter(price__in=(456.23,111))
# print(res4)
# 范围查询
# res5 = models.Books.objects.filter(price__range=(100,456.23))
# print(res5)
# 模糊查询
# 查询书籍名称中含有字母a的书
# res6 = models.Books.objects.filter(title__contains='a')
# print(res6) # 区分
# res7 = models.Books.objects.filter(title__icontains='a')
# print(res7) # 忽略大小写
# 日期相关
# 查看出版月份是五月的书
# res8 = models.Books.objects.filter(publish_time__month=5)
# print(res8)
# print(res8.query)
# res9 = models.Books.objects.filter(publish_time__year=2021)
# print(res9)8.多表查询之外键字段增删改查
# 增
# models.Book.objects.create(title='三国演义',price=345.43,publish_id=1)
# models.Book.objects.create(title='红楼梦',price=678.31,publish_id=2)
# publish_obj = models.Publish.objects.filter(pk=2).first()
# models.Book.objects.create(title='三国演义',price=345.43,publish=publish_obj)
# models.Book.objects.create(title='七龙珠',price=908.43,publish=publish_obj)
# 改
# models.Book.objects.filter(pk=2).update(publish_id=1)
# models.Book.objects.filter(pk=2).update(publish=publish_obj)
# 删 级联更新级联删除
# models.Publish.objects.filter(pk=1).delete()
# 多对多
book_obj = models.Book.objects.filter(pk=3).first()
# 绑定关系
# book_obj.authors.add(1) # 去书与作者的关系表中绑定关系
# book_obj.authors.add(1,2) # 去书与作者的关系表中绑定关系
# book_obj.authors.add(author_obj1)
# book_obj.authors.add(author_obj1,author_obj2)
# 修改关系
# book_obj.authors.set([1,])
# book_obj.authors.set([1,2])
# book_obj.authors.set([author_obj,])
# book_obj.authors.set([author_obj1,author_obj2])
# 移除关系
# book_obj.authors.remove(1)
# book_obj.authors.remove(1,2)
# book_obj.authors.remove(author_obj,)
# book_obj.authors.remove(author_obj1,author_obj2)
# 清空关系
book_obj.authors.clear()
