Returning a list with python magic methods in django models.py

Question

I needed to select multiple items in a models.py (subjects app) which is linked with ForeignKey to another models.py (tutors). I get an error while trying to add items to the database after selecting multiple items in a topics var: "str expects a string but got a list". How do I use the python magic method or some other method in my models.py to return a list of selection and add same to the database?

See below my models.py:

from django.db import models
from multiselectfield import MultiSelectField

# Create your models here.
class Subject(models.Model):
    TOPICS = (
        ('SAT', 'SAT'),
        ('ACT', 'ACT'),
        ('GED', 'GED'),
        ('GRE', 'GRE'),
        ('READING', 'READING'),
        ('WRITING', 'WRITING'),
        ('ESL/ESOL', 'ESL/ESOL'),
        ('ALGEBRA', 'ALGEBRA'),
        ('CALCULUS', 'CALCULUS'),
        ('TRIG', 'TRIG'),
        ('GEOMETRY', 'GEOMETRY'),
        ('CHEMISTRY', 'CHEMISTRY'),
        ('PHYSICS', 'PHYSICS'),
        ('BIOLOGY', 'BIOLOGY'),
        ('CODING', 'CODING'),
        ('STATISTICS', 'STATISTICS'),
        ('FRENCH', 'FRENCH'),
        ('SPED', 'SPED'),
    )

    topics = MultiSelectField(choices = TOPICS,blank=True)
    level = models.IntegerField(default=1)

    def __str__(self):
        return self.topics

Thanks for assisting as I have come to my wits end. Done a lot of research online without luck

Answer 1

self.topics is a list and for string representation you could concatenate list items into string

    def __str__(self):
        return ','.join(self.topics)

Answer 2

From looking at your models, it seems like you could use a many-to-many relationship instead. See the official django documentation .