这里的问题是当模型仍在加载且应用未完全初始化时，您正在查询数据库：

The problem here is you're querying the database while models are still loading and apps are not fully initialized:

File "/Users/hugokitano/Documents/Summer_Code/statread/stats/models.py", line 40, in CompareForm
select = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple,required=False,choices=( (x.id, x.con_name) for x in CONTROL_CHOICES) )          

CONTROL_CHOICES 是先前在文件中定义的查询集：

CONTROL_CHOICES is a queryset defined earlier in your file:

CONTROL_CHOICES = Control.objects.all()

为简单起见，请永远不要这样做。如果在未完全加载应用程序的情况下查询数据库，则所有内容都会崩溃。

To keep it simple, never, never do this. If you query the database while your apps are not fully loaded, everything will crash.

此外，您的代码也将无法正常运行：

Also, your code will not behave as expected:

class CompareForm(forms.Form):
    select = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple,required=False,choices=( (x.id, x.con_name) for x in CONTROL_CHOICES) )          

因为您直接在查询集中迭代您的表单定义中，您将获得一个静态元素列表，这些元素在您重新启动服务器之前不会改变（即使您在数据库中添加了新元素）。

Since you are iterating on the queryset directly in your form definition, you will get a static list of elements that will never change (even if you add new ones in database) until you restart your server.

此处的解决方案是摆脱 forms.MultipleChoiceField 和 CONTROL_CHOICES 并使用 ModelMultipleChoiceField 。
专门针对这种情况设计：

The solution Here is to get rid of forms.MultipleChoiceField and CONTROL_CHOICES and use ModelMultipleChoiceField. It is designed specifically for this case:

class CompareForm(forms.Form):
    select = forms.ModelMultipleChoiceField(queryset=Control.objects.all())

由于对查询集的计算是惰性的，显示表单时，您将直接从数据库获取最新的对象。
Django还将为您处理验证和所有操作。

As the queryset is lazily evaluated, you'll get up-to-dase objects straight from the database when displaying the form. Django will also handle validation and everything for you.