Extend Model's Queryset with additional attributes

Question

I have simple Django model with some internet sessions (Radius logs). And want to show it in my template.

models.py:

class Radacct(models.Model):
    radacctid = models.BigIntegerField(primary_key=True)
    username = models.CharField(max_length=253)
    nasipaddress = models.IPAddressField()
    class Meta:
        db_table = u'radacct'

view.py:

def ajax_radius_sessions(request, username):
    radius_sessions = Radacct.objects.filter(username=username).order_by('-radacctid')

template.html:

{% for session in radius_sessions %}
    {{ session.username }}, {{ session.nasipaddress }}</br>
{% endfor %}

In my template, I need to show the hostname based on user's ip-address (nasipaddress) as well.

Method 1: Creation of Model's method.

I do not want to calculate Hostname as Model's method, because it will be triggered for every record, but the number of session for particular user can be very big — in this case it will cause huge amount of DNS-checks. 1000 sessions = 1000 DNS checks?..

Method 2a: View level.

I was trying to this on View level, to check only unique IPs and get the "local" dictionary with IP-Hostname pairs:

#servers={'192.168.100.1':'alpha', '192.168.100.2':'beta', '192.168.100.3':'gamma'}

But I can not access this dictionary in the template, using the key as variable:

#Wrong!
{{ servers[session.nasipaddress] }}

Method 2b: View level. Adding new attribute to the Queryset instance.

Maybe I can add a new attribute to my Radacct Model which is not connected with database. And fill it by hostname, in my View?

What is the proper way to calculate some "attribute" and then access it in the Template in Queryset {% for %} loop?

Again: it seems I can not do this as Model's method, so I think I should extend my database results with custom ones.

P.S. Sorry for a really looong post. This is my very first try on Stackoverflow. Thank you!

Answer 1

Model "method". Create a separate class that is responsible for looking up DNS entries and caching them, and refer to an instance of this class in a descriptor on the model.