views.py

我们在urls.py中写的转发方法,都需要有参数request
request包含了所有用户请求的信息。

def news(request):
    return render(request, 'news.html')

request

我们在urls.py中的方法的参数request,包含了请求头所有的信息。

1)request.method
请求方式:GET/POST

2)request.POST 和 request.GET
这里的POST或者GET相当于对应方式提交过来的封装好的字典。

request.POST['username']
request.POST['password']

跨表查询:

    {% for row in hosts%}
  • {{row.nid}} - {{row.hostname}} - {{row.ip}} - {{row.port}} - {{row.bussiness.id}} - {{row.bussiness_id}}
  • {% endfor %}

bussiness_id是一个外键,bussiness_id与bussiness.id的值是一样的,但是它们有一些不一样的地方,那就是bussiness.id经过了跨表查询,而bussiness_id在表中直接有。


三种查询结果的方式:
1)直接

models.Host.objects.filter(id=1)

2)values,获得字典为基础的QuerySet

models.Host.objects.all().values('id', 'hostname', 'port')

3)value_list,以元组为基础的QuerySet

models.Host.objects.all().value_list('id', 'hostname', 'port')

values跨表查询

双下划线(__)的作用:

v2 = models.Host.objects.filter(id=1).values('id', 'hostname', 'business_id', 'business__caption')

注意:这里必须是双下划线(__),而不能是点(.


经验:

1.上一页,下一页,查询优化:

def productdetails(request, nid):

    data = getData()

    wine_one = models.Winery.objects.filter(id=nid).first()
    wine_first = models.Winery.objects.all().first()
    wine_last = models.Winery.objects.all().last()

    if nid <= wine_first.id:
        nid = 1
    elif nid > wine_last.id:
        nid = wine_last.id 

    temp_id = nid

    while wine_one == None:

        temp_id = temp_id + 1

        wine_one = models.Winery.objects.filter(id=str(temp_id)).first()
        if temp_id > wine_last.id:
            wine_one = wine_first
            break

    data['wine_one'] = wine_one

    print (data['wine_one'].title)  # there ouput the "gaoliangjiu"

    return render(request, 'article_list_content.html', {'data':data})

2.请求:

views.py:

def detail(request, id):
    article = get_object_or_404(Article, pk=id)
    return render(request, "page/detail.html", context)

3.查询的时候filter删选,可以传入字典

dict = {'article_type_id':1, 'category_id':2}
result = models.Article.objects.filter()

request请求内容。

views.py_第1张图片
图片.png

给响应头添加数据


views.py_第2张图片
给响应头添加数据.png

4.在views.py的def方法中:

def test(request):
    print(type(request))
    return HttpResponse("

test ok!

")

请求来的request是WSGIRequest:

返回的是HttpResponse

5.try...except...else...finally

try:
     Normal execution block
except A:
     Exception A handle
except B:
     Exception B handle
except:
     Other exception handle
else:
     if no exception,get here
finally:
     print("finally")   

下面的代码的执行可以确定queryset是懒加载,可以先保存,然后再取:

def favorite(request, album_id):
    album = get_object_or_404(Album, pk=album_id)
    try:
        selected_song = album.song_set.get(pk=request.POST['song'])
    except (KeyError, Song.DoesNotExist):
        return  render(request, 'music/detail.html', {
            "album":album,
            "error_message":"You did not select a valid song",
        })
    else:
        selected_song.is_favorite = True
        selected_song.save()
        return render(request, 'music/detail.html', {
            "album":album,
        })

generic views

示例:

from django.views import generic

class IndexView(generic.ListView):
    template_name = 'music/index.html'
    context_object_name = 'album_list'  # 注意:默认的是objects_list
    
    def get_queryset(self):
        return Album.objects.all()   # 注意:默认的是objects_list

CreateView,UpdateView,DeleteView:

from django.views.generic.edit import CreateView,UpdateView,DeleteView

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