django-models 數據庫取值

django.shortcuts import render,HttpResponse
from app01.models import *
# Create your views here.

def index(request):
    return render(request,"index.html")

def addbook(request):
    # 一對多的添加



    # 第一種方式
    # Book.objects.create(name="Linux運維",price=1133,pub_date="2017-11-22",publish_id=2)



    # 第二種添加方式 publish_id,沒辦法添加publish_obj
    # publish_obj=Publish.objects.filter(name="人民出版社")[0]
    # print("+++!!!****",publish_obj)
    # +++!!!**** Publish object (1)
    # print(type(publish_obj))
    # <class 'app01.models.Publish'>

    # Book.objects.create(name="GO語言", price=43, pub_date="2017-07-17", publish_id=2)
    # INSERT INTO `app01_book` (`name`, `price`, `pub_date`, `publis
    # h_id`) VALUES ('GO語言', 43, '2017-07-17', 2); args=['GO語言', 43, '20
    # 17-07-17', 2]



    # 拿到數據庫里面的表的值,有兩步,先拿到值,再賦給對象
    # 再從里面取值
    # 先拿到book表,取到name=python的值,再賦給對象
    # 如果是兩個值,會報錯,get只能得到一個值
    # book_obj=Book.objects.get(name='python')
    #
    # print("----",book_obj)



    # 一對多:book_obj.publish------一定是一個對象
    # 如果是要取外鍵的表的值,取publish會取到一個publish對象
    # print(type(book_obj.publish))
    # print(book_obj.publish.name)
    # print(book_obj.publish.city)



    # 從子表去找主表
    # 要拿到表中外鍵的表的值,步驟有
    # 先拿到publish表是name的值等於機械出版社的一整行對象pub_obj(表中有id,name,city)
    # SELECT `app01_publish`.`id`, `app01_publish`.`name`, `app01_pu
    # blish`.`city` FROM `app01_publish` WHERE `app01_publish`.`name` = '機
    # 械出版社'; args=('機械出版社',)
    # 把pub_obj結果賦值給publish,由id作為查找依據,再從book表中找到要查詢的name跟price
    # SELECT `app01_book`.`name`, `app01_book`.`price` FROM `app01_b
    # ook` WHERE `app01_book`.`publish_id` = 4  LIMIT 21; args=(4,)

    # get查找方式:表.objects.get()--只能有一個對象
    # pub_obj=Publish.objects.get(name='機械出版社')

    # filter查找方式:表.objects.filter()[0]--是對象的集
    # pub_obj2=Publish.objects.filter(name="山西出版社")[0]
    # print(pub_obj)
    # Publish object (4)

    # print(pub_obj.city)
    # 上海
    # print(pub_obj.id)
    # 4

    # 關鍵點:把publish表的對象放進filter里面篩選,再從里面values取值
    # ret=Book.objects.filter(publish=pub_obj).values("name","price")
    # ret2=Book.objects.filter(publish=pub_obj2).values("name","pub_date")

    # print(ret)
    # print(ret2)
    # 機械出版社出版的書籍跟價格---query對象
    # <QuerySet [{'name': 'Java', 'price': 65}, {'name': 'Linux開發', 'price
    # ': 1133}, {'name': 'Linux系統', 'price': 133}, {'name': 'Linux服務器',
    #  'price': 133}]>



    # 從主表再去找子表
    # ,第一步相同,從publish表找到name等於南方出版社,賦值給pub_obj
    pub_obj = Publish.objects.filter(name='山西出版社')[0]
    # 再從pub_obj里面找到book_set.all()(book子表的所有內容) 是一個對象集合

    # publish表拿到了book表的對象,表名+單引號,得到了表名里面的queryset對象.all()的所有值,
    # book_set.all(),再從里面values取值
    print(pub_obj.book_set.all())
    # <QuerySet [<Book: Django>, <Book: Linux運維>, <Book: sqlyog>, <Book: Linux代碼>, <Book: GO語言>, <Book: GO語言>, <Book: GO語言>, <Book: moring>]>

    print(pub_obj.book_set.all().values("name",'price'))
    # <QuerySet [{'name': 'Django', 'price': 45}, {'name': 'Linux運維', 'pri
    # ce': 1133}, {'name': 'sqlyog', 'price': 1133}, {'name': 'Linux代碼', '
    # price': 133}, {'name': 'GO語言', 'price': 43}, {'name': 'GO語言', 'pri
    # ce': 43}, {'name': 'GO語言', 'price': 43}, {'name': 'moring', 'price':
    #  23}]>

    # 更簡便的第3種方式:
    ret=Book.objects.filter()