django brookie - “NoneType”对象没有属性“状态”；

Question

前几天偶然发现了 Brookie 应用程序并浏览了一下。非常适合在保存时创建发票 PDF。

但是，我在创建新发票时遇到此错误。我知道出现错误是因为没有对象，因此它不能有属性。

class InvoiceAdmin(admin.ModelAdmin):
    list_display = ('client', 'status', 'date', total_monetized, is_expired, pdf_invoice)
    list_filter = ('status', 'client')
    exclude = ('invoice_no',)
    ordering = ('id', )
    search_fields = ['client__company', ]
    readonly_fields = ()
    inlines = [ItemInline,]

class Media:
    js = ('http://ajax.googleapis.com/ajax/libs/jquery/1.4.3/jquery.min.js', 'brookie/js/brookie.js')

def get_readonly_fields(self, request, obj=None):
    readonly = super(InvoiceAdmin, self).get_readonly_fields(request, obj)

    # if the invoice is send you can no longer alter it
    if obj.status in br_settings.INVOICE_FINISH_STATUS:
        readonly = ('invoice_id', 'client', 'date', 'currency', 'tax', 'hourly_rate')

    return readonly

def save_model(self, request, obj, form, change):
    obj.save()
    if obj.status in br_settings.INVOICE_FINISH_STATUS:
        # Set the invoice id
        if not obj.invoice_no:
            invoice_list = Invoice.objects.filter(invoice_no__isnull=False).order_by('-invoice_no')
            try:
                invoice = invoice_list[0]
            except:
                # There are no numbered invoices
                invoice_no = getattr(br_settings, 'INVOICE_START_NUMBER', 1)
            else:
                invoice_no = invoice.invoice_no + 1
            obj.invoice_no = invoice_no
            obj.save()

        # Generate the pdf for this invoice
        context_dict = {'invoice': obj,
                        'client': obj.client,
                        'items': obj.items.all(),}

        generate_pdf(obj.invoice_id, context_dict, "brookie/invoice_%s_pdf.html" % obj.currency, save=True)

我尝试了各种方法来测试只读字段之前对象的存在性。如果发票处于非开发状态，则返回只读字段 (1)

如果对象是新对象，如何忽略 get_readonly_fields 函数？ 我还尝试向模型添加 default=1，在尝试访问状态属性但未成功之前测试 obj 是否存在。

预先感谢

##编辑##

Traceback:
File "C:\Python26\lib\site-packages\django\core\handlers\base.py" in get_response
  100.                     response = callback(request, *callback_args, **callback_kwargs)
File "C:\Python26\lib\site-packages\django\contrib\admin\options.py" in wrapper
  239.                 return self.admin_site.admin_view(view)(*args, **kwargs)
File "C:\Python26\lib\site-packages\django\utils\decorators.py" in _wrapped_view
  76.                     response = view_func(request, *args, **kwargs)
File "C:\Python26\lib\site-packages\django\views\decorators\cache.py" in _wrapped_view_func
  69.         response = view_func(request, *args, **kwargs)
File "C:\Python26\lib\site-packages\django\contrib\admin\sites.py" in inner
  190.             return view(request, *args, **kwargs)
File "C:\Python26\lib\site-packages\django\utils\decorators.py" in _wrapper
  21.             return decorator(bound_func)(*args, **kwargs)
File "C:\Python26\lib\site-packages\django\utils\decorators.py" in _wrapped_view
  76.                     response = view_func(request, *args, **kwargs)
File "C:\Python26\lib\site-packages\django\utils\decorators.py" in bound_func
  17.                 return func(self, *args2, **kwargs2)
File "C:\Python26\lib\site-packages\django\db\transaction.py" in _commit_on_success
  299.                     res = func(*args, **kw)
File "C:\Python26\lib\site-packages\django\contrib\admin\options.py" in add_view
  773.         ModelForm = self.get_form(request)
File "C:\Python26\lib\site-packages\django\contrib\admin\options.py" in get_form
  356.         exclude.extend(self.get_readonly_fields(request, obj))
File "C:\Sites\media\bread-and-pepper-django-brookie-a1a8102\brookie\admin.py" in get_readonly_fields
  124.         if obj.status in br_settings.INVOICE_FINISH_STATUS:

Exception Type: AttributeError at /admin/brookie/invoice/add/
Exception Value: 'NoneType' object has no attribute 'status'

Answer 1

问题是，即使在 obj 为 None 的情况下，您也尝试评估 status 属性，这显然是可接受的情况。

要修复它，您可以将其更改

# if the invoice is send you can no longer alter it
if obj.status in br_settings.INVOICE_FINISH_STATUS:
    readonly = ('invoice_id', 'client', 'date', 'currency', 'tax', 'hourly_rate')

为：

# if the invoice is send you can no longer alter it
if obj and obj.status in br_settings.INVOICE_FINISH_STATUS:
    readonly = ('invoice_id', 'client', 'date', 'currency', 'tax', 'hourly_rate')