Duplicate model field in Django

Question

A duplicate model field is giving me trouble (no such table appname_modelname when I run my webpage). Whenever I do ./manage.py migrate appname, it gives me "duplicate field". I checked my models.py, there is only one of them there. How do I delete that duplicate field? It seems no matter what I do, it stays. I've tried:

Deleting the database
Deleting migrations folder in app folder
Doing ./manage.py sqlclear south and then dropping the south_migrationhistory table in the dbshell
./manage.py schemamigration appname --initial, ./manage.py migrate appname --fake

I've run out of ideas.

class Document(models.Model):
    filename = models.CharField(max_length=255, blank=True, null=True, default=None)
    identity = models.CharField(max_length=255, default=None, null=True)
    user = models.ForeignKey(User, null=False)
    user_id = models.IntegerField(User, null=True)
    docfile = models.FileField(upload_to=_upload_path, storage=fs) # upload_to is a path inside the storage path

    def get_upload_path(self,filename):
        return str(self.user.id) + '/' + str(date.today()) + '/' + filename

Please post the model in which duplicate field error is coming — Pawan, Jul 14 '14 at 11:26
Why user_id seems to be necessary ? user and user_id are both same fields. — Pawan, Jul 14 '14 at 11:29
I would get an error saying this field was missing if I didn't a long time ago. I found this really strange but I gave up on debugging it because I couldn't find the error. — KSHMR, Jul 14 '14 at 11:30
Hm - this is strange. I deleted the database again and did the things I said in the OP again and now it works... Thanks for spending time on this though! — KSHMR, Jul 14 '14 at 11:33
Very much strange , I think I can help you , so in user field , you want user id who created document , right? — Pawan, Jul 14 '14 at 11:34
IntegerField dont required to add User model as reference (as this not making any sence). `models.IntegerField(User, null=True)` instead just use `models.IntegerField(null=True)` — MaNKuR, Jul 14 '14 at 13:37

score 5 · Answer 1 · edited Jul 15 '14 at 21:40

You can't do this, for your user foreign key, Django ORM will create a database field named user_id (your foreign key field name plus _id) to use it as a FK in the database.

You don't have to create this field yourself (the ORM will take care), even if you need it, change the name of the attribute user or user_id.

From the documentation:

Behind the scenes, Django appends "_id" to the field name to create its database column name. In the above example, the database table for the Car model will have a manufacturer_id column. (You can change this explicitly by specifying db_column) However, your code should never have to deal with the database column name, unless you write custom SQL. You’ll always deal with the field names of your model object.

MaNKuR · Answer 2 · 2014-07-14T13:39:04.110

Not sure but problem causing here in these two line

user = models.ForeignKey(User, null=False)
user_id = models.IntegerField(User, null=True)

Better to use "related name" attribute to avoid the duplicate error as in database "user" will be added as user_id.

user = models.ForeignKey(User, related_name="id_user") # Change the related field as your convenience
user_id = models.IntegerField(null=True, related_name="user_id")

Check if this resolve your issues

Duplicate model field in Django

2 Answers2