Allow directories in filename argument to save_<fieldname>_file

[Adam Endicott <leftwing17@…>]

Currently, all files associated with FileFields are uploaded into a single directory specified by MEDIA_ROOT and upload_to. There is no way to specify directories on a per-file basis when files are uploaded. With this patch, if the filename argument to save_<fieldname>_file specifies a directory as well as a filename, the file will be uploaded to that directory under the MEDIA_ROOT/upload_to directory. Example:

class File(meta.Model):
    file = meta.FileField(upload_to='baseDir')
    name = meta.CharField(maxlength=100)

newFile = files.File(name='my file')
newFile.save_file_file('some/sub/directory/myFile.txt', 'Some text content')

The above lines will create a file at: <MEDIA_ROOT>/baseDir/some/sub/directory/myFile.txt.

This shouldn't change how most file uploading (including the admin app) works now, because normally just a filename without any directories is passed to save_<fieldname>_file. However, it allows custom view code or FileField subclasses (each of which will call save_<fieldname>_file) to save files to specific locations easily.

[Philippe Raoult]

will be solved by #5361

[James Bennett]

Closing as a duplicate of #5361 per PhiR's comment above.