How can I create a model with a field that is having a list of values? (For example a model called group with multiple members) Is it possible to implement the relationship with many to many fields?
3 Answers
Here is a example with multiple selection options
class Members(models.Model):
MEMBERS = {
(0, 'James'),
(1, 'Jeremy'),
(2, 'Alex'),
}
number = models.PositiveSmallIntegerField(default=0)
names = models.PositiveSmallIntegerField(default=0, choices=MEMBERS)
1 Comment
Kevin
Your answer is describing multiple choice where only one value is selected at a time. Whereas the question is asking about choosing multiple values to be selected at the same time.
You are looking for Many2Many Field. For example:
class User(models.Model):
# relevant fields
...
class Team(models.Model):
# other fields
members = models.ManyToManyField(User, related_name='teams')
Note several things about this solution:
- Users can be members of multiple teams (that is why Many2Many relationship)
- User model can reference all teams, he is part of:
user.teams_set
If you want a User to be member of only one team, than ForeignKey is the right way to go:
class User(models.Model):
# other fields
team = models.ForeignKey('Team')
...
class Team(models.Model):
# relevant fields
...
For more information consult documentation: https://docs.djangoproject.com/en/3.1/topics/db/examples/many_to_many/
3 Comments
ams_py
Thanks for the answer @LynxLike. Also how can I add data to the many to many field?
LynxLike
You simply add appropriate model instance to the field. In your example:
team = Team.objects.create(...) and user = User.objects.create(...). Then you simply assing the user to the team via team.members.add(user)ams_py
When I tried printing
team.members after team.members.add(user) team.save() and then it is showing like User.None which means the data is not getting saved to the instance. How can I fix this issue ?I do this one time. if you working with the PostgreSQL database in Django projects, in my search you can do like this
from django.contrib.postgres.fields import ArrayField
class MyModal (models.Model):
array_field= ArrayField(models.IntegerField(null=True,blank=True),null=True,blank=True)
