Django模型不能保存查詢

Question

我一直在Django工作了一段時間，現在我遇到了這個奇怪的問題。

我在流網站增加一個等級的功能，爲此，我寫了一個是通過URL稱爲視圖：

url(r'^channel/rate/(?P<stream_id>[\d]*)/(?P<rate>[\d]*)/?$', 'eros.streaming.views.view_rate_channel', 
    name='view_rate_channel'), 

def view_rate_channel(request,stream_id,rate): 
    if(stream_id and rate and request.user.is_authenticated()): 
     stream= Stream.objects.get(id=stream_id) 
     if stream not in request.user.channel.rated_streams.all(): 
      if stream.channel.user != request.user: 
       channel=Channel.objects.get(stream=stream) 
       channel.rating= channel.rating+int(rate)  
       print("channel rating: "+str(channel.rating)) 
       #this prints fine in any case 
       channel.n_voters = channel.n_voters +1 
       channel.save() 
       stream.rating= stream.rating+int(rate) 
       stream.n_voters= stream.n_voters+1 
       stream.save()  
       request.user.channel.rated_streams.add(stream) 
       request.user.channel.save() 
       return HttpResponseRedirect('/channel/'+str(stream.channel.id)+'/') 
    return HttpResponseRedirect('/channel/'+str(stream.channel.id)+'/') 

當我檢查了數據庫，改變我的頻道即將播出channel.save（）之後的對象沒有保存，只有Stream對象發生了奇怪的變化。

所以做一些調試完畢後，我決定發表評論這個如果我使用，因此用戶不能率流不止一次：

 ##if stream not in request.user.channel.rated_streams.all(): 

而且現在channel.save（）的工作！壞事是我不能讓用戶不止一次地評價一個流。

繼承人的模型的簡化版本：

class Channel(models.Model): 
    user = models.OneToOneField(User) 
    rating = models.IntegerField(default=0) 
    n_voters = models.IntegerField(default=0) 
    rated_streams = models.ManyToManyField('Stream', related_name="rated_streams") 
    description = models.TextField(default="") 

class Stream(models.Model): 
    ## I think that maybe this relation is what is causing me trouble (?): 
    channel = models.ForeignKey(Channel) 
    rating = models.IntegerField(default=0) 
    n_voters = models.IntegerField(default=0) 

有什麼不好的做法或壞的查詢，我做的是正在發生的呢？提前致謝。

Answer 1

使用channel = stream.channel代替channel = Channel.objects.get(stream=stream)修復了此問題。