How can I efficiently get related data from a 1 to 1 related table in Django?

I have the following models. (I include only part of the actual full definition since the rest isn't relevant to the question.)

class Event(models.Model):
    uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    created_at = models.DateTimeField(auto_now_add=True)
    last_updated = models.DateTimeField()
    title = models.CharField(max_length=255)
    description = models.TextField(blank=True, null=True)

class Translation(models.Model):
    event = models.ForeignKey(Event, related_name="translation_event", on_delete=models.CASCADE, null=True)
    title = models.CharField(max_length=255)
    description = models.TextField(null=True, blank=True)

I want to create a queryset on the Event table and then join that with the translated data.
In other words, I want a left outer join between the Event table and the Translation table.

If I have a queryset (called queryset) on the Event table, from what I understand from a number of examples I saw as well as the documentation, I should be able to do the following:

queryset = queryset.select_related("translation_event")
for event_obj in queryset:
    print(event_obj.title)
    print(event_obj.translation_event.title)

However, when Django gets to the for event_obj in queryset: line, it throws an exception:

> django.core.exceptions.FieldError: Invalid field name(s) given in
> select_related: 'translation_event'.

(It then lists some valid field names, fields in the Event table that have foreign key relationships to other tables.)

It almost seems like the select_related allows going from the Event table to other tables, but doesn't allow the other direction where the foreign key is in the second table - even though it should.

Any help would be appreciated.

I hope I understand you correctly: You are looking for reverse lookups, right?

Going from Translation to Event is easy.

trnsl = Translation.objects.all().first()
print(trnsl.translation_event)

The other way round is called reverse lookup. One Translation belongs to one specific Event. But one specific Event can have a set of Translations. I don't know whether or not that makes sense for your usecase, but that is the logic of ForeignKey. An alternative would be OneToOneField (more). The phrasing "has a set of" already leads you to the python syntax of reverse lookups. Do it like this:

evnt = Event.objects.all().first()  # grab an event
for related_trnsl in evnt.translation_set.all():
    print(related_trnsl)

You`ll find more about related lookups here. Just search the site for "_set" and you'll find it quicker.