Django - get object stored in Foreign Key

Question

Possible Duplicate:
Django FileField with upload_to determined at runtime

I am creating a web application that allows user to store files online, like Dropbox. A user's file is modeled by the model Item:

from django.db import models
from django.contrib.auth.models import User


class Item(models.Model):
    # Name of file
    name = models.CharField(max_length=200)

    # Site user who owns the file
    user = models.ForeignKey(User)

    # Path to file in database
    # Python complains here since "username" is an attribute of the User class, not
    # an attribute of ForeignKey.
    file = models.FileField(upload_to=(user.username + '/' + name))

Now if you look the upload_to argument to FileField, I want to specify where files are stored in my database. If I have a user "bill" with file "myfile" his file should go under the path "bill/myfile".

To get this string I tried "user.username + '/' + name" but python complains that user doesn't have an attribute username because user isn't a User object: it's a ForeignKey that stores a User. So the question is, how do I get the user object from the ForeignKey within code?

Now regarding Django's database API that won't work because the object has to be saved to the database before I can use the API. This is not the case as I need the data during construction of my Item object.

Files aren't stored in your database. Their paths are stored in your database, but the files (typically) are stored in directories on disk, at your MEDIA_ROOT + the upload_to argument. — orokusaki, Aug 21 '12 at 01:34

score 1 · Accepted Answer · answered Aug 21 '12 at 00:56

1

With FileField you can put a [function on upload_to][1]

https://docs.djangoproject.com/en/dev/ref/models/fields/#django.db.models.FileField.upload_to

answered Aug 21 '12 at 00:56

Tarsis Azevedo

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score 1 · Answer 2 · answered Aug 21 '12 at 04:09

Your approach is flawed either way because whatever you pass into upload_to is going to be called once. Even if user.username worked, you have to remember that it's only calculated when the class is defined.

You'll want to define a custom upload_to function to pass to the field.

def custom_upload_to(instance, filename):
     return '{instance.user.username}/'.format(instance=instance)

myfield = models.FileField(upload_to=custom_upload_to)

Django - get object stored in Foreign Key

2 Answers2