Reverse foreign key with cross reference table - Django Rest Framework - django

Question

I'm trying to create an API endpoint which will provide summary data about a user and the groups they are in.
My current models have User and UserGroup connected with a Membership Model.
My current problem is I can't seem to get the list of group members to work.
Am I on the right track here? Or is there a better way to handle serialization/querying of models with many to many relationships?
Models:
class UserGroup(models.Model):
group_id = models.AutoField(primary_key=True)
name = models.CharField(max_length=30)
description = models.CharField(max_length=200)
deleted = models.BooleanField(default=False)
class Membership(models.Model):
group = models.ForeignKey(UserGroup, on_delete=models.CASCADE, related_name="members")
user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="user_groups")
isAdmin = models.BooleanField(default=False)
Serializers:
class MemberSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = User
fields = ('first_name', 'last_name')
class MembershipSerializer(serializers.HyperlinkedModelSerializer):
name = serializers.ReadOnlyField(source='group.name')
description = serializers.ReadOnlyField(source='group.description')
members = MemberSerializer(source='group.members', read_only=True, many=True)
class Meta:
model = Membership
fields = ('name', 'description', 'members')
class UserSerializer(serializers.ModelSerializer):
groups = MembershipSerializer(source='user_groups', read_only=True, many=True)
class Meta:
model = User
fields = ('username', 'groups')
Current Output:
{
"username": "User 1",
"groups": [
{
"name": "Group 1",
"description": "Test Group",
"members": [
{}
]
},
{
"name": "Group 2",
"description": "Test Group 2",
"members": [
{}
]
}
]
}
Expected:
'members' contains a list of users who are in the UserGroup.

Answer 1

I think your code is too complex.
Models:
from django.contrib.auth import models as dj_models
class Group(models.Model):
group_id = models.AutoField(primary_key=True)
name = models.CharField(max_length=30)
description = models.CharField(max_length=200)
deleted = models.BooleanField(default=False)
members = models.ManyToManyField(dj_models.User, through='Membership', related_name='user_groups')
class Membership(models.Model):
group = models.ForeignKey(Group, on_delete=models.CASCADE)
user = models.ForeignKey(dj_models.User, on_delete=models.CASCADE)
isAdmin = models.BooleanField(default=False)
Serializers:
from django.contrib.auth import models as dj_models
class MemberSerializer(serializers.ModelSerializer):
class Meta:
model = dj_models.User
fields = ('username',)
class GroupSerializer(serializers.ModelSerializer):
members = MemberSerializer(many=True, read_only=True)
class Meta:
model = models.Group
fields = ('name', 'description', 'members')
class UserSerializer(serializers.ModelSerializer):
groups = GroupSerializer(many=True, read_only=True, source='user_groups')
class Meta:
model = dj_models.User
fields = ('username', 'groups')
Output:
[
{
"username":"Account 01",
"groups":[
{
"name":"Group 01",
"description":"Test Group",
"members":[
{
"username":"Account 01"
}
]
},
{
"name":"Group 02",
"description":"Test Group 2",
"members":[
{
"username":"Account 01"
}
]
}
]
}
]