django-models 数据库取值

  1 django.shortcuts import render,HttpResponse
  2 from app01.models import *
  3 # Create your views here.
  4 
  5 def index(request):
  6     return render(request,"index.html")
  7 
  8 def addbook(request):
  9     # 一对多的添加
 10 
 11 
 12 
 13     # 第一种方式
 14     # Book.objects.create(name="Linux运维",price=1133,pub_date="2017-11-22",publish_id=2)
 15 
 16 
 17 
 18     # 第二种添加方式 publish_id,没办法添加publish_obj
 19     # publish_obj=Publish.objects.filter(name="人民出版社")[0]
 20     # print("+++!!!****",publish_obj)
 21     # +++!!!**** Publish object (1)
 22     # print(type(publish_obj))
 23     # <class 'app01.models.Publish'>
 24 
 25     # Book.objects.create(name="GO语言", price=43, pub_date="2017-07-17", publish_id=2)
 26     # INSERT INTO `app01_book` (`name`, `price`, `pub_date`, `publis
 27     # h_id`) VALUES ('GO语言', 43, '2017-07-17', 2); args=['GO语言', 43, '20
 28     # 17-07-17', 2]
 29 
 30 
 31 
 32     # 拿到数据库里面的表的值,有两步,先拿到值,再赋给对象
 33     # 再从里面取值
 34     # 先拿到book表,取到name=python的值,再赋给对象
 35     # 如果是两个值,会报错,get只能得到一个值
 36     # book_obj=Book.objects.get(name='python')
 37     #
 38     # print("----",book_obj)
 39 
 40 
 41 
 42     # 一对多:book_obj.publish------一定是一个对象
 43     # 如果是要取外键的表的值,取publish会取到一个publish对象
 44     # print(type(book_obj.publish))
 45     # print(book_obj.publish.name)
 46     # print(book_obj.publish.city)
 47 
 48 
 49 
 50     # 从子表去找主表
 51     # 要拿到表中外键的表的值,步骤有
 52     # 先拿到publish表是name的值等于机械出版社的一整行对象pub_obj(表中有id,name,city)
 53     # SELECT `app01_publish`.`id`, `app01_publish`.`name`, `app01_pu
 54     # blish`.`city` FROM `app01_publish` WHERE `app01_publish`.`name` = '机
 55     # 械出版社'; args=('机械出版社',)
 56     # 把pub_obj结果赋值给publish,由id作为查找依据,再从book表中找到要查询的name跟price
 57     # SELECT `app01_book`.`name`, `app01_book`.`price` FROM `app01_b
 58     # ook` WHERE `app01_book`.`publish_id` = 4  LIMIT 21; args=(4,)
 59 
 60     # get查找方式:表.objects.get()--只能有一个对象
 61     # pub_obj=Publish.objects.get(name='机械出版社')
 62 
 63     # filter查找方式:表.objects.filter()[0]--是对象的集
 64     # pub_obj2=Publish.objects.filter(name="山西出版社")[0]
 65     # print(pub_obj)
 66     # Publish object (4)
 67 
 68     # print(pub_obj.city)
 69     # 上海
 70     # print(pub_obj.id)
 71     # 4
 72 
 73     # 关键点:把publish表的对象放进filter里面筛选,再从里面values取值
 74     # ret=Book.objects.filter(publish=pub_obj).values("name","price")
 75     # ret2=Book.objects.filter(publish=pub_obj2).values("name","pub_date")
 76 
 77     # print(ret)
 78     # print(ret2)
 79     # 机械出版社出版的书籍跟价格---query对象
 80     # <QuerySet [{'name': 'Java', 'price': 65}, {'name': 'Linux开发', 'price
 81     # ': 1133}, {'name': 'Linux系统', 'price': 133}, {'name': 'Linux服务器',
 82     #  'price': 133}]>
 83 
 84 
 85 
 86     # 从主表再去找子表
 87     # ,第一步相同,从publish表找到name等于南方出版社,赋值给pub_obj
 88     pub_obj = Publish.objects.filter(name='山西出版社')[0]
 89     # 再从pub_obj里面找到book_set.all()(book子表的所有内容) 是一个对象集合
 90 
 91     # publish表拿到了book表的对象,表名+单引号,得到了表名里面的queryset对象.all()的所有值,
 92     # book_set.all(),再从里面values取值
 93     print(pub_obj.book_set.all())
 94     # <QuerySet [<Book: Django>, <Book: Linux运维>, <Book: sqlyog>, <Book: Linux代码>, <Book: GO语言>, <Book: GO语言>, <Book: GO语言>, <Book: moring>]>
 95 
 96     print(pub_obj.book_set.all().values("name",'price'))
 97     # <QuerySet [{'name': 'Django', 'price': 45}, {'name': 'Linux运维', 'pri
 98     # ce': 1133}, {'name': 'sqlyog', 'price': 1133}, {'name': 'Linux代码', '
 99     # price': 133}, {'name': 'GO语言', 'price': 43}, {'name': 'GO语言', 'pri
100     # ce': 43}, {'name': 'GO语言', 'price': 43}, {'name': 'moring', 'price':
101     #  23}]>
102 
103     # 更简便的第3种方式:
104     ret=Book.objects.filter()