Question

I am new to django and I am having some issues when I try to save a mapping.

from django.db import models

# Create your models here.
class Users(models.Model):
        user = models.CharField(max_length=45)
        password = models.CharField(max_length=125)
        env = models.CharField(max_length=10)
        class Meta:
                db_table = 'esp-users'
        def __unicode__(self):
                return unicode(self.user)
class Groups(models.Model):
        group_name = models.CharField(max_length=45)
        description = models.CharField(max_length=255)
        env = models.CharField(max_length=45)
        class Meta:
                db_table = 'esp-groups'
        def __unicode__(self):
                return unicode(self.group_name)
class Roles(models.Model):
        role_name = models.CharField(max_length=45)
        env = models.CharField(max_length=10)
        class Meta:
                db_table = 'esp-roles'
        def __unicode__(self):
                return unicode(self.role_name)
class Group_Map(models.Model):
        group_id = models.ForeignKey(Groups, db_column='id')
        user_id = models.ForeignKey(Users, db_column='id')
        class Meta:
                db_table='esp-group-map'
        def __unicode__(self):
                return unicode(self.group_id)
class Role_Map(models.Model):
        role_id = models.ForeignKey(Roles, db_column='id')
        group_id = models.ForeignKey(Groups, db_column='id')
        class Meta:
                db_table='esp-role-map'
        def __unicode__(self):
                return unicode(self.role_id)

Thanks for the help.

Django V 1.3, Python 2.4, Mysql 5.0.77

Request Method: POST
Request URL: http://somehost:8100/admin/users_admin/group_map/add/
Django Version: 1.3
Exception Type: DatabaseError
Exception Value:

(1110, “Column ‘id’ specified twice”)

Lesson Learned: If its a new database isntead of making the tables yourself just run python manage.py syncdb and it will make the db for you and all is good. Thanks for the help!

Answer 1

You can’t do this:

group_id = models.ForeignKey(Groups, db_column='id')
user_id = models.ForeignKey(Users, db_column='id')

You just need to do:

group_id = models.ForeignKey(Groups)
user_id = models.ForeignKey(Users)

Django will infer what column to use based on Users and Groups primary keys.

While you are at it, I would recommend you to change Groups into Group, Users into User and so on, so forth. Your code will be more clear since you will do stuff like:

user = User()

Instead of:

user = Users()