Django框架之queryset数据类型

 

from django.shortcuts import render,HttpResponse
from book.models import Book
import datetime
# Create your views here.
def add_book(request):

    #添加书籍
    # 方式1
    #date = datetime.date(year=2012,month=12,day=12)
    #book = Book(title="xiyouji", price=199, pub_date=date)
    book = Book(title="xiyouji",price=199,pub_date="2012-12-12")
    print(book.id) #None
    book.save() #执行sql
    print(book.id) # 3

    # 方式2
    book = Book.objects.create(title="sanguoyanyi",price=299,pub_date="2011-11-11")
    print(book.id)
    print(book.price)

def select_book(request):
    # (1) 查询所有的书籍，返回值是一个queryset类型对象
    book_list= Book.objects.all()
    '''
    ORM数据引擎：
    
    select id, title, price, pub_date from book:
    +------+--------------+---------+------------+
    id  title             price     pub_date
    +------+--------------+---------+------------+
    1    西游记            499.00     2011-12-12
    2    三国演义          399.00     2019-06-12
    3    水浒传            299.00     2008-06-12
    4    红楼梦            199.00     2020-06-12
    +------+--------------+---------+------------+
    book01 = Book(1 | 西游记  |499.00 |2011-12-12)
    book02 = Book(2 | 三国演义  |399.00  |2019-06-12)
    book03 = Book(3 | 水浒传    |299.00  |2008-06-12)
    book04 = Book(4 | 红楼梦    |199.00  |2020-06-12)
    
    book_list = queryset[book01,book02,book03,book04]    
    
    '''
    print ("book_list",book_list) # <QuerySet [<Book: Book object (1)>,...]

    #QuerySet:支持索引操作，支持遍历
    book = book_list[0]
    print(book.id) # 1
    print(book.title) # 西游记
    print(book.price) # 499.00
    # print(book_list.title)
    for book in book_list:
        print (book.id,book.title)  #1 西游记 2 三国演义 3 水浒传 4 红楼梦

    return HttpResponse("添加书籍")