django：在模型字段中添加多个值

Question

i want to create a app for classroom in which their only one teacher and students can be more than one.a nd student can be in more than one class. i want to store usernames of students in one classroom. is there any model field i can use to store usernames of students. my code so far:

models.py

from django.db import models
from django.conf import settings
# Create your models here.

class classroom(models.Model):
    teacher = models.ForeignKey(settings.AUTH_USER_MODEL, default=1)
    students = models.CharField(max_length=120)

Answer 1

Create a Student model and add a many to many key to a ClassRoom instance. In that way you are telling " A student may have several classroom and a classroom may have many students "

class ClassRoom(models.Model):
    teacher = models.ForeignKey(settings.AUTH_USER_MODEL, default=1)


 class Student(models.Model):
    name = models.CharField(max_length=120)
    classroom =  models.ManyToManyField(ClassRoom, related_name="students")

So, if you have a classroom instance and want to get all its student. Notice the related_name attribute in the field classroom.

classroom.students.all()

If you don't add related_name attribute, you will need to use _set notation

classroom.student_set.all()

If you have a student instance and want to get his classroom

student.classroom

TIP: For class model naming, use CamelCase notation.

Answer 2

You should create a separate model for storing students, but even more than that - you should really start with the Django tutorial on their official site.

But your problem is solved accordingly:

from django.db import models
from django.conf import settings

class ClassRoom(models.Model):
    teacher = models.ForeignKey(settings.AUTH_USER_MODEL, default=1)

class Student(models.Model):
    name = models.CharField(max_length=128)
    class_room = models.ForeignKey(ClassRoom)

This way you can add as many students as you like. This is the standard practice, but if you really want to just save the names and NOTHING else (and are using PostgreSQL), you can also use the ArrayField for that. But check it out in the documentation yourself.