Got it working somehow. However, it's a very bad solution and I would appreciate every other idea.
I used django-tables2 Template Column:
class EventTable(tables.Table):
#override messplatz-column
messplatz = tables.TemplateColumn('{% load url from future %}<a href="{% url \'messplatz_events\' record.messplatz %}">{{ record.get_messplatz }}</a>')
#Hint: {% load url from future %} is only needed for django versions < 1.5
class Meta:
model = Event
To access record.get_messplatz, I had to move the get_messplatz method to the Event-Model:
from prodis.models import Messplatz
class Event(models.Model):
messplatz = models.IntegerField()
def get_messplatz(self):
return Messplatz.objects.get(mpl_id=self.messplatz)
Won't mark this as solution, because I think it's a very bad one. But I hope this answer helps.