ContentFile未保存在Django模型FileField中 [英] ContentFile not saved in Django model FileField

问题描述

在我的Django模型中将字符串另存为文件时遇到问题，因为每当我尝试取回数据时，都会给我一个ValueError（属性没有关联的文件）。详细信息如下：

I have a problem when saving Strings as file in my Django models, as whenever I try to get the data back, it gives me a ValueError ("attribute has no file associated"). Here's the details:

模型：

class GeojsonData(models.Model):
dname = models.CharField(max_length=200, unique=True)
gdata = models.FileField(upload_to='data')
def __str__(self):
    return self.dname

保存数据的代码：

cf = ContentFile(stringToBeSaved)
gj = GeojsonDatua(dname = namevar, gdata = cf)
gj.save()

尝试读取数据的代码：

def readGeo(data):
    f = GeojsonData.objects.all().get(id=data.id).gdata
    f.open(mode ='rb')
    geo = f.read()
    return geo

回溯：

File "C:\Python\Python36-32\lib\site-packages\django\core\handlers\exception.py" in inner
  41.             response = get_response(request)

File "C:\Python\Python36-32\lib\site-packages\django\core\handlers\base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "C:\Python\Python36-32\lib\site-packages\django\core\handlers\base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "C:\Python\Python36-32\lib\site-packages\django\contrib\auth\decorators.py" in _wrapped_view
  23.                 return view_func(request, *args, **kwargs)

File "C:\app\views.py" in mapa
  80.           geostr = app.readGeo.readGeo(d)

File "C:\app\readGeo.py" in readGeo
  6.    f.open(mode ='rb')

File "C:\Python\Python36-32\lib\site-packages\django\db\models\fields\files.py" in open
  80.         self._require_file()

File "C:Python\Python36-32\lib\site-packages\django\db\models\fields\files.py" in _require_file
  46.             raise ValueError("The '%s' attribute has no file associated with it." % self.field.name)

Exception Type: ValueError at /app/map/1
Exception Value: The 'gdata' attribute has no file associated with it.

推荐答案

您需要将ContentFile保存为实际文件。而不是直接将其分配给该字段，您应该调用该字段的 save 方法并将其传递给：

You need to save the ContentFile as an actual file. Rather than assigning it directly to the field, you should call the field's save method and pass it in:

gj = GeojsonDatua(dname = namevar)
gj.gdata.save('myfilename', cf)

请参见文档。

请注意，如果您始终创建 gdata 字段，您可能根本不需要FileField。也许改用TextField。

Note also, if you're always creating your gdata field like this you probably don't want a FileField at all; perhaps use a TextField instead.

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