Multiple individual users on one database

Question

I have a .sql database with which i interact using Django . The database in the beginning is filled with public data that can be accessed from anynone. Multiple individual users can add rows into a table(private data). How can a user see only the changes he made in the database(private data)?

Answer 1

I'm assuming that users have to log into this application. If yes, add a column to every table for the username. Add WHERE username = ? to every query so they can see only their data.

For data manipulation requests, make sure that the username matches the value for every row; forbid the operation if not true.

Answer 2

I assume you're using django.contrib.auth. You just need to do something like:

from django.contrib.auth.models import User

# ...

class PrivateData(models.Model):
    # ... private data fields ...
    user = models.ForeignKey(User)

Then you can get just that user's fields with:

PrivateData.objects.filter(user=request.user)

EDIT: So, if your users are just IP addresses, and you're not using a login mechanism, you don't really need django.contrib.auth... though it's good to have anyway since you can use it to authenticate yourself and use the built-in admin stuff to manage your site.

If you just want to tie data to IP addresses, set up an IPUser model:

class IPUser(models.Model):
    address = models.CharField(max_length=64, unique=True) # Big enough for IPv6
    # Add whatever other discrete (not list) data you want to store with this address.

class PrivateData(models.Model):
    # ... private data fields ...
    user = models.ForeignKey(IPUser)

The view function looks something like:

def the_view(request):
    remoteAddr = request.META['REMOTE_ADDR']
    try:
        theUser = IPUser.objects.get(address=remoteAddr)
    except IPUser.DoesNotExist:
        theUser = IPUser.objects.create(address=remoteAddr)
    userModifiedData = PrivateData.objects.filter(user=theUser)

One thing to note: when you're testing this with manage.py runserver, you'll need to specify the IP address via environment variable:

$ REMOTE_ADDR=127.0.0.1 manage.py runserver

When you use Django with a real web server like Apache, the server will set the variable for you.

There are probably several ways to optimize this, but this should get you started.