Replace field with model

[hugorodgerbrown]

Having the S3Upload field allows any text field on a model to become S3 compatible, however at large scale it can get out of hand - S3 interactions are spread across all models in the project. An alternative approach (which I've worked with in the past, with millions of files) is to have a single file-tracking model, and a OneToOne relationship on the model where required.

class TestModel(models.Model):

    # store the upload path on the model
    file1 = S3UploadField(dest='foo')

    # store the upload as separate object
    file2 = models.OneToOneField(S3Upload)

The advantage of this is that all uploads are held in a single table, and you can add useful metadata to each - the model field it is stored against, timestamps etc. The additional advantage is that you can then key audit events off this object - uploads, downloads etc. (See #5)

The disadvantage is that the initial implementation is harder - hooking the widget up so that you are creating the object and then the relationship to the parent, etc.

Both approaches could be combined - use the model if you want auditing, use the field if you don't.