Counting objects within a Foreign Key and ManyToMany in Django

I'd like to count the objects I have listed.

I would like to count the number of issues within each title.

This is how my models.py are setup:

# Edited out

Views.py:

def titles (request):
    all_titles = Title.objects.all().o开发者_Python百科rder_by('title')
    num_titles = Title.objects.all().count()
    latest_titles = Title.objects.order_by('-date_added')
    title_a = Title.objects.filter(title__startswith='A')
    title_b = Title.objects.filter(title__startswith='B')

     ......etc......

I need to do this for creators and characters too, except they are in a Many to Many relationship with Issue and the views essentially look the same as the def titles

Thank you.

---

To get the related issues for each title you can use the backwards relationship lookup. Since you did not specify a related name in the Issue model where you created the relationship, the lookup is performed using _set appended to the lower cased name of the related model. In your case issue_set.

some_title = Title.object.get(pk=1)
some_title.issue_set.count()

However, this is going to perform a db hit for every title you want to count.

You probably want to annotate the titles qs with the count. docs

from django.db.models import Count
titles_with_counts = Title.objects.all().annotate(issue_count=Count('issue__id'))

now each title in that qs has count accessible by using .issue_count

for title in titles_with_counts:
    print title.title, title.issue_count