Django help required with non foreign key relations

[Aditya Sriram M]

File myapp/models.py has this sample code..

from django.db import models

# model for 'user' table in database oracle_dbuser1:user 
class User(models.Model):
    . . .
    customerid = models.BigIntegerField()

# model for 'customer' table in database oracle_dbuser2:customer
# Note that there is no Foreign key integrity among these legacy tables.
class Customer(models.Model):
    . . .
    customerid = models.BigIntegerField()

and the file myapp/admin.py has the following code:

from maasusers.models import User, Customer
from django.contrib import admin

class UserAdmin(admin.ModelAdmin):
    # A handy constant for the name of the alternate database.
    db_one = 'dbuser1'
    db_two = 'dbuser2'

    # display in a list
    list_display = (. . .) # question 1

    def queryset(self, request):
        result = super(UserAdmin, self).queryset(request).using(self.db_one) # question 2
        return result

# Register the Poll class
admin.site.register(User, UserAdmin)
admin.site.register(Customer, UserAdmin)

Question 1: Refer above: I want to display columns of both the tables. How can I achieve this? Eg.Select usr.col1, usr.col2, cust.col1, cust.col10 from user usr, customer cust where usr.col2 = cust.col3;

Question 2: How to write a corresponding queryset() function using the using function?

[akaariai]

There is no way to do a join between models if there is no relation
between them. I see two ways forward: modify one of the models to have
a foreign key - even if there is no foreign key in the DB, you can
have one in the models - or do the join in Python (fetch all
customers, then fetch users by
User.objects.filter(customerid__in=[obj.customerid for obj in
customers]). Finally join users to its customer).

- Anssi

[Aditya Sriram M]

Ohh this looks little promising..

However,

1. I need a few cols of table1 and few from table 2 to be displayed. How can we achieve that at the .filter() level? and 
2. At the view level like using the list_display () for displaying them in the Admin interface

[akaariai]

On Apr 23, 8:15 am, Aditya Sriram M <aditya.cr3...@gmail.com> wrote:
> Ohh this looks little promising..
>
> However,
>

>    1. I need a few cols of table1 and few from table 2 to be displayed. How

>    can we achieve that at the .filter() level? and

>    2. At the view level like using the list_display () for displaying them
>    in the Admin interface

If you want to get results just define the ForeignKey (or OneToOneKey)
in your Customer or User model. After this .select_related
and .prefetch_related should solve the problems you are currently
facing.

If you can't define that ForeignKey for one reason or another you need
a lot more knowledge of how Django works. All the things you need to
do are too numerous to handle in a django-users post. It is possible
there will be some problems which are very hard to solve along this
path.

In short, I recommend to just define the relation between the models.

- Anssi