django-models 数据库取值
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2022-06-05 14:25:32
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... ......
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()
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