Verify my django model config

Question

Just starting out with Django, however I think I've screwed up my model layout. I don't think I have a full understanding of relationships just yet.

Here is what I desire:

my model layout

Here is my model.py

edit: I modified it a bit as per below

from django.db import models

class User(models.Model):
        username = models.CharField(max_length=30, unique=True)
        password = models.CharField(max_length=100)
        birthday = models.DateField('birthday')
        email = models.EmailField(max_length=100)
        SEX = (
         ('M', 'Male'),
         ('F', 'Female'),
        )
        usersex = models.CharField(max_length=1, choices=SEX)
        height = models.CharField(max_length=3)
        createdat = models.DateField('join date')

        def __str__(self):
                return "%s %s %s %s %s %s" % (self.username, self.birthday, self.email, self.usersex, self.height, self.createdat)

class UserBench(models.Model):
        username = models.ForeignKey(User, related_name='bench', to_field='username')
        date = models.DateField()
        reps = models.IntegerField()
        weight = models.IntegerField()

        def __str__(self):
                return "%s %s %s %s" % (self.username, self.date, self.reps, self.weight)

class UserSquat(models.Model):
        username = models.ForeignKey(User, related_name='squat', to_field='username')
        date = models.DateField()
        reps = models.IntegerField()
        weight = models.IntegerField()

        def __str__(self):
                return "%s %s %s %s" % (self.username, self.date, self.reps, self.weight)

class UserDeadlift(models.Model):
        username = models.ForeignKey(User, related_name='deadlift', to_field='username')
        date = models.DateField()
        reps = models.IntegerField()
        weight = models.IntegerField()

        def __str__(self):
                return "%s %s %s %s" % (self.username, self.date, self.reps, self.weight)

class UserStats(models.Model):
        username = models.ForeignKey(User, related_name='stats', to_field='username')
        date = models.DateField()
        bodyweight = models.IntegerField()

        def __str__(self):
                return "%s %s %s %s" % (self.username, self.date, self.reps, self.weight)

Is this correct? I think I wanted to have a "ManyToManyField" instead of "ForeignKey".

Or, thinking about it, maybe I should have somehow added the foreign-key columns to the person? This is because each person will have 1 lift (but multiple entries in the database)...so that confuses me somewhat.

Also, what about my "to_field"? I think that's what I want to do, however I'm not sure if django handles that automatically and I've just screwed it up.

edit: I guess I am confused as to how to now join the data.

If I do:

 User.squat.all()
 AttributeError: 'ForeignRelatedObjectsDescriptor' object has no attribute 'all'

If I do:

 user = User.Objects.filter(username = 'name')
 user.deadlift.all()
 Traceback (most recent call last):
 File "<console>", line 1, in <module>
 AttributeError: 'QuerySet' object has no attribute 'deadlift'

If I do:

 * Login to admin interface
 * Go to UserSquat, and click "add user"
 * The username is now EVERY field from User, so for e.g. it's detecting the username as "name 1989-05-16 email@domain.com M 180 2015-11-17" (Which are the fields in User table)

picture for reference

So I've got myself very confused and broken everything ha. Thanks again.

Answer 1

Your use of ForeignKey is good! To make use of them, assign a related_name to each foreign key field, like so:

class UserSquat(models.Model):
        username = models.ForeignKey(User, related_name='squats')

That way, whenever you have a user, you can access all of their squat objects (?) via user.squats.all() .

If multiple users can share squats for some reason, ManyToManyField s are used. The format does not change.

class UserSquat(models.Model):
        # A squat can belong to more than one user
        username = models.ManyToManyField(User, related_name='squats')