Retrieving child models

Using Django
#1

I have an app called Blog. In my models.py there is a class BaseEntry and classes that inherit from it like SimpleEntry and TitledEntry. For the index view I want all the Entries in one list.

I defined my list view like this.

class BlogListView(ListView):
    model = BaseEntry
    template_name = 'blog/index.html'
    paginate_by = 5

I’m thinking I could do something like this:

BaseEntry.objects.all()

Then I could go through the list and retrieve the child instances by their parents ids.

Or instead I could do something like this right away:

SimpleEntry.objects.all()
TitledEntry.objects.all()

The thing that bothers me: I define the view to work with a particular model, but then I work with a different model. On the other hand the documentation says this:
“A QuerySet that represents the objects. If provided, the value of queryset supersedes the value provided for model .”
Am I taking the model attribute too serious or could I run into trouble with thie second approach?

#2

Remember that the relationship between a concrete base class and a child class is the establishment of a OneToOne relationship from the child class to the parent.

This means that you can do something like BaseEntry.objects.all(), and then check to see whether a particular instance has an attribute simpleentry or titledentry to identify which child class is related to it.

1 Like
#3

django-model-utils’ InheritanceManager may help with resolving child models: https://django-model-utils.readthedocs.io/en/latest/managers.html#inheritancemanager

However, with too many different child models you may run into performance trouble because of too many outer joins. But it might just work really well and solve your problem.