反向数据库信息django(reverse database information django)

我想要添加最后5个项目。我真的不知道该怎么做。我尝试了reverse（）函数。限制我使用的查询[：5]

额外的问题：请求上下文是什么？我不懂djangodocs

模型：

class Topic(models.Model): user = models.ForeignKey(User) postit = models.TextField(max_length=300) comment = models.TextField(max_length=300) createdat = models.DateTimeField(default=timezone.now) def timer(self): return self.createdat def who(self): return self.user def __str__(self): # __unicode__ on Python 2 return self.postit

视图：

def chat(request): if request.method == 'POST': form = StoryForm(request.POST) if form.is_valid(): storyi = form.save(commit=False) storyi.user = request.user storyi.save() return HttpResponseRedirect('/chat/') else: form=StoryForm() try: p = Topic.objects.all()[:5].reverse() ) except ObjectDoesNotExist: p= "don't try it again" return render(request,'chat/chat.html',{'form': form, 'p':p})

I am trying to get last 5 items added. I really don't know how to do this. I tried the reverse() function . to limit the query i used [:5]

extra question: whats the request context for? i didn't understand djangodocs

model:

class Topic(models.Model): user = models.ForeignKey(User) postit = models.TextField(max_length=300) comment = models.TextField(max_length=300) createdat = models.DateTimeField(default=timezone.now) def timer(self): return self.createdat def who(self): return self.user def __str__(self): # __unicode__ on Python 2 return self.postit

View:

def chat(request): if request.method == 'POST': form = StoryForm(request.POST) if form.is_valid(): storyi = form.save(commit=False) storyi.user = request.user storyi.save() return HttpResponseRedirect('/chat/') else: form=StoryForm() try: p = Topic.objects.all()[:5].reverse() ) except ObjectDoesNotExist: p= "don't try it again" return render(request,'chat/chat.html',{'form': form, 'p':p})

最满意答案

如果最后一个添加你的意思是列表中的最后一个，它应该是[-5：]。例如：

In [22]: a =[1,2,3,4,5,6,7,8,9,10] In [23]: a[:5] Out[23]: [1, 2, 3, 4, 5] In [26]: a[-5:] Out[26]: [6, 7, 8, 9, 10]

你对RequestContext有什么兴趣？ RequestContext将返回特定值作为响应。例：

def my_view(request): # View code here... t = loader.get_template('myapp/index.html') c = RequestContext(request, {'foo': 'bar'}) return HttpResponse(t.render(c))

在这里，您返回带有渲染值的'index.html'模板{'foo':''bar}

更新：在您的情况下，您可以像这样使用RequestContext：

return render（request，'chat / chat.html'，{'form'：form，'p'：p}）

......

template = loader.get_template('chat/chat.html') c=RequestContext(request, {'form': form, 'p':p}) return HttpResponse(template.render(c))

If last added you mean last in list, it should be [-5:]. for example:

In [22]: a =[1,2,3,4,5,6,7,8,9,10] In [23]: a[:5] Out[23]: [1, 2, 3, 4, 5] In [26]: a[-5:] Out[26]: [6, 7, 8, 9, 10]

What exactly are you interest in RequestContext? RequestContext is to return specific values in response. Example:

def my_view(request): # View code here... t = loader.get_template('myapp/index.html') c = RequestContext(request, {'foo': 'bar'}) return HttpResponse(t.render(c))

Here you return 'index.html' template with rendered values {'foo':''bar}

UPDATE: In your case you can use RequestContext like this:

return render(request,'chat/chat.html',{'form': form, 'p':p})

......

template = loader.get_template('chat/chat.html') c=RequestContext(request, {'form': form, 'p':p}) return HttpResponse(template.render(c))

更多推荐