Django中的多对多更新字段

Question

我有两个具有多对多关系的模型，我正在尝试使用表单来更新字段。提出请假后，会通过电子邮件通知董事。主管可以使用该表格登录系统以批准休假。批准休假后，我要调整Leave_current_balance field模型中的LeaveBalance。该函数引发错误：u'Leave_current_balance' on the line current_balance=form.fields['Leave_current_balance']

class LeaveBalance(models.Model):
    user=models.OneToOneField(User,on_delete=models.CASCADE,primary_key=True,)
    Leave_current_balance= models.FloatField(null=True, blank=True, default=None)



class NewLeave(models.Model):
    user=models.ForeignKey(User,default='',on_delete=models.CASCADE)
        leave_balance=models.ManyToManyField(Leave_Balance)
        leave=(
        ('annual','annual'),
        ('sick','sick'),

        )

    Leave_type=models.CharField(max_length=100,choices=leave,blank=False,default='')

        Total_working_days=models.FloatField(null=True,  blank=False)
        DirAuth=(
            ('Pending','Pending'),
            ('Approved','Approved'),
            ('Rejected','Rejected'),
        )

        Director_Authorization_Status=models.CharField(max_length=100,choices=DirAuth,default='Pending',blank=False)
    Date_Authorized=models.DateField(null=True,blank=False)
    Authorized_by_Director=models.CharField(max_length=100,default='',blank=False)

        def __unicode__(self):
            return  self.Leave_type




class DirectorForm(forms.ModelForm):
    class Meta:
        model=NewLeave
        fields=('Director_Authorization_Status','Authorized_by_Director','Date_Authorized',)
        widgets={
            'Date_Authorized':DateInput()
        }

此函数引发错误：u'Leave_current_balance'

def unitDirectorForm(request,id):

    if request.method=='POST':

        getstaffid=NewLeave.objects.get(id=id)
        form = DirectorForm(request.POST, instance=getstaffid)
        if form.is_valid():
            getstaffid = form.save(commit=False)
            getstaffid.save()

            total_days = getstaffid.Total_working_days
            current_balance = getstaffid.user.leave_balance.Leave_current_balance
            diff_balance = current_balance - total_days
            current_balance = diff_balance
            current_balance=form.fields['Leave_current_balance']
            current_balance.save()
            getstaffid.leave_balance.add(current_balance)

            return HttpResponse('You have successfuly Authorise the leave')

    else:
        #getstaffid=NewLeave.objects.get(id=id)
        form=DirectorForm()
        #c_balance=Leave_Balance.objects.get()
        balance_form = leavebbalanceForm()

    return render(request,'managerauthorisedform.html',{'form':form})

TraceBack：

Request Method: POST
Request URL: http://127.0.0.1:8000/unitDirectorForm/25/

Django Version: 1.11.18
Python Version: 2.7.15
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'mathfilters',
 'profilepage']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']



Traceback:

File "/root./virtualenvs/eleave/local/lib/python2.7/site-packages/django/core/handlers/exception.py" in inner
  41.             response = get_response(request)

File "/root./virtualenvs/eleave/local/lib/python2.7/site-packages/django/core/handlers/base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "/root./virtualenvs/eleave/local/lib/python2.7/site-packages/django/core/handlers/base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/var/www/projects/eleave/profilepage/views.py" in unitDirectorForm
  179.                 current_balance=form.fields['Leave_current_balance']

Exception Type: KeyError at /unitDirectorForm/25/
Exception Value: u'Leave_current_balance'