在保存对象之前处理文件上传 [英] Processing file uploads before object is saved

问题描述

我有一个这样的模型：

class Talk(BaseModel):
  title        = models.CharField(max_length=200)
  mp3          = models.FileField(upload_to = u'talks/', max_length=200)
  seconds      = models.IntegerField(blank = True, null = True)

我要在保存上传的文件是MP3之前验证，如下所示：

I want to validate before saving that the uploaded file is an MP3, like this:

def is_mp3(path_to_file):
  from mutagen.mp3 import MP3
  audio = MP3(path_to_file)
  return not audio.info.sketchy

一旦我确定我有一个MP3，我想保存长度在秒属性中的谈话，像这样：

Once I'm sure I've got an MP3, I want to save the length of the talk in the seconds attribute, like this:

audio = MP3(path_to_file)
self.seconds = audio.info.length

问题是，在保存之前，上传的文件没有路径请参阅此门票，关闭为 wontfix ），所以我无法处理MP3。

The problem is, before saving, the uploaded file doesn't have a path (see this ticket, closed as wontfix), so I can't process the MP3.

我想提出一个很好的验证错误，以便 ModelForm 可以显示一个有用的错误（你傻子，你没有上传MP3或某事）。

I'd like to raise a nice validation error so that ModelForms can display a helpful error ("You idiot, you didn't upload an MP3" or something).

任何想法我可以在保存文件之前访问该文件吗？

Any idea how I can go about accessing the file before it's saved?

^{ps如果有人知道更好的验证文件的方式是MP3，我都是耳朵 - 我也想要弄清ID3的数据（设置艺术家，专辑，标题和可能的专辑封面，所以我需要它可以处理诱变剂）。}

推荐答案

您可以访问 request.FILES ，而在您的视图中。

You can access the file data in request.FILES while in your view.

我认为最好的方法是将上传的文件绑定到表单，覆盖表单 clean method ，获取 UploadedFile对象从clean_data，验证它，无论如何你喜欢，然后覆盖保存方法，并使用有关该文件的信息填充您的模型实例，然后保存。

I think that best way is to bind uploaded files to a form, override the forms clean method, get the UploadedFile object from cleaned_data, validate it anyway you like, then override the save method and populate your models instance with information about the file and then save it.

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