Django inner join methods return unexpected results

Question

I am new to Django's ORM and am confused by inner join conventions despite having consulted the documentation and other answers on SO. I have two tables - MyPoints and MyBuffers that are one-to-one related by projectid (no duplicates in either table). My goal is to fetch the radius field using inner join on projectid. Even though I have defined a foreign key, my first attempt at fetching all of the fields from MyBuffers returns nothing from the joined table, and my second attempt at fetching one field from MyBuffers errors. What is wrong with the syntax or methodology here? Should key columns be named differently? Any advice would be greatly appreciated!

models.py

from django.contrib.gis.db import models

class MyBuffers(models.Model):
    id = models.BigAutoField(primary_key=True)
    projectid = models.CharField(max_length=25, unique=True)
    radius = models.IntegerField(blank=True, null=True)

    class Meta:
        managed = False
        db_table = 'my_buffers'

class MyPoints(models.Model):
    id = models.BigAutoField(primary_key=True)
    projectid = models.ForeignKey('MyBuffers', max_length=25, on_delete=models.DO_NOTHING, to_field='projectid', db_column='projectid')
    geog = models.PointField(geography=True, srid=4326) 

    class Meta:
        managed = False
        db_table = 'my_points'

views.py

from .models import MyPoints
from .models import MyBuffers

1.Does not return any fields in from the joined MyBuffers table

test = MyPoints.objects.select_related('projectid')
test.first().__dict__

{'_state': <django.db.models.base.ModelState object at 0x7f3e21786520>, 'id': 5808, 'projectid_id': 'foobar1', 'geog': <Point object at 0x7f3e21738910>}

2.Throws an errors

test= MyPoints.objects.select_related('projectid__radius')
test.first().__dict__
django.core.exceptions.FieldError: Non-relational field given in select_related: 'radius'. Choices are: (none)

Answer 1

I think select related only works in foreign keys. So if you are trying to get fields other than foreign keys it will throw an error. Your queryset must be

test= MyPoints.objects.select_related('projectid')
# To get radius
test.first().projectid.radius