Django 多对多字段的更新和插入数据实例

#插入数据
def add(request):
 
 G_title=request.POST.get('title')#-------值为：python书本
 
 G_publish=request.POST.get('publish') #-------值为：1
 G_authors_list=request.POST.getlist('authors')#-------值为：[3,7]
 
 
 
 publish_obj=Publish.objects.get(id=G_publish)#查找Publish表对应id的obj 
 authors_obj_list=Author.objects.filter(id__in=G_authors_list)#查找Author表对应id的多个obj
 
 title  #-------普通字段
 publish  #-------一对多外键
 authors  #-------多对多外键
 
 book_obj=Book.objects.create(title=G_title,publish=publish_obj)#添加普通和一对多外键的值
 
 
 #添加多对多外键的值
 方式一
 book_obj.authors.add(*authors_obj_list)
 方式二
 for obj in authors_obj_list:
  book_obj.authors.add(obj)
 
 return redirect('/index/')

def edit(request,b_id):#b_id-----为书本的id
 
 G_title=request.POST.get('title')#-------值为：linux书本
 
 G_publish = request.POST.get('publish')#-------值为：2
 G_authors_list = request.POST.getlist('authors')#-------值为：[3,5]
 
 
 book_obj = Book.objects.get(id=b_id)#查找Book表要修改的id对象
 
 publish_obj = Publish.objects.get(id=G_publish)#查找Publish表对应id的obj
 author_objs = Author.objects.filter(id__in=G_authors_list)#查找Author表对应id的多个obj
 
 
 book_obj.title=G_title   #-------修改普通字段
 book_obj.publish=publish_obj #-------修改一对多字段
 book_obj.authors=author_objs #-------修改多对多字段 
 #注意：多对多字段 必须是.all()/.filter()等的查询集(QuerySet)
 book_obj.save()     #-------一定得save(),才能对数据库进行修改
 
 return redirect('/index/')

 # 添加作者 ringo
 ringo = Author.objects.create(name='Ringo',email='ringo@qq.com')
 # 添加作者paul
 paul = Author.objects.create(name='Paul',email='paul@qq.com')
 # 添加书籍 python book1
 book1 = Book.objects.create(title='python book1')
 # 给多对多添加值也就是添加多对多关系
 m1 = BookAuthor(author=ringo,book=book)
 # 第二种添加方式
 m2 = BookAuthor.objects,create(author=paul,book=book1)