[models] Replaced JSONField with Django's built-in #600

- Replaced third-party jsonfield.JSONField with Django's built-in
  models.JSONField in all model definitions
- Updated RadiusBatch.prefix_add method to directly assign
  user_credentials list instead of using json.dumps()
- Added migration 0043 to replace JSONField in model definitions
- Added migration 0044 to convert existing double-encoded JSON data
  in user_credentials field (data migration in separate file)
- Used .iterator() in data migration for memory efficiency
- Removed jsonfield dependency from setup.py
- Updated test migrations to use Django's JSONField
- Removed unused json import

Closes #600

Author: Eeshu-Yadav

openwisp_radius/base/models.py

@@ -1,6 +1,5 @@
 import csv
 import ipaddress
-import json
 import logging
 import os
 import string
@@ -18,12 +17,11 @@
 from django.core.exceptions import ObjectDoesNotExist, ValidationError
 from django.core.mail import send_mail
 from django.db import models
-from django.db.models import ProtectedError, Q
+from django.db.models import JSONField, ProtectedError, Q
 from django.utils import timezone
 from django.utils.crypto import get_random_string
 from django.utils.timezone import now
 from django.utils.translation import gettext_lazy as _
-from jsonfield import JSONField
 from model_utils.fields import AutoLastModifiedField
 from openwisp_notifications.signals import notify
 from phonenumber_field.modelfields import PhoneNumberField
@@ -1021,7 +1019,7 @@ def prefix_add(self, prefix, n, password_length=BATCH_DEFAULT_PASSWORD_LENGTH):
         for user in users_list:
             user.full_clean()
             self.save_user(user)
-        self.user_credentials = json.dumps(user_credentials)
+        self.user_credentials = user_credentials
         self.full_clean()
         self.save()
 

openwisp_radius/migrations/0043_alter_organizationradiussettings_sms_meta_data_and_more.py

@@ -0,0 +1,31 @@
+# Generated by Django 5.2.5 on 2025-10-22 18:34
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("openwisp_radius", "0042_set_existing_batches_completed"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="organizationradiussettings",
+            name="sms_meta_data",
+            field=models.JSONField(
+                blank=True,
+                help_text=(
+                    "Additional configuration for SMS backend in JSON format "
+                    "(optional, leave blank if unsure)"
+                ),
+                null=True,
+                verbose_name="SMS meta data",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="radiusbatch",
+            name="user_credentials",
+            field=models.JSONField(blank=True, null=True, verbose_name="PDF"),
+        ),
+    ]

openwisp_radius/migrations/0044_convert_user_credentials_data.py

@@ -0,0 +1,33 @@
+# Generated by Django 5.2.5 on 2025-11-18 00:00
+
+import json
+
+from django.db import migrations
+
+
+def convert_user_credentials_data(apps, schema_editor):
+    """
+    Convert existing double-encoded JSON strings in user_credentials field
+    to proper JSON objects for Django's built-in JSONField.
+    """
+    RadiusBatch = apps.get_model("openwisp_radius", "RadiusBatch")
+    for batch in RadiusBatch.objects.exclude(user_credentials__isnull=True).iterator():
+        if isinstance(batch.user_credentials, str):
+            batch.user_credentials = json.loads(batch.user_credentials)
+            batch.save(update_fields=["user_credentials"])
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        (
+            "openwisp_radius",
+            "0043_alter_organizationradiussettings_sms_meta_data_and_more",
+        ),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            convert_user_credentials_data, reverse_code=migrations.RunPython.noop
+        ),
+    ]

setup.py

@@ -49,7 +49,6 @@
         "weasyprint>=65,<67",
         "dj-rest-auth>=6.0,<7.1",
         "django-sendsms~=0.5.0",
-        "jsonfield~=3.1.0",
         "django-private-storage~=3.1.0",
         "django-ipware>=5.0,<7.1",
         "pyrad~=2.4",

tests/openwisp2/sample_radius/migrations/0002_initial_openwisp_app.py

@@ -7,7 +7,6 @@
 import django.core.validators
 import django.db.models.deletion
 import django.utils.timezone
-import jsonfield.fields
 import model_utils.fields
 import private_storage.fields
 import private_storage.storage.files
@@ -543,7 +542,7 @@ class Migration(migrations.Migration):
                 ),
                 (
                     "sms_meta_data",
-                    jsonfield.fields.JSONField(
+                    models.JSONField(
                         blank=True,
                         help_text=(
                             "Additional configuration for SMS backend in JSON format"
@@ -695,9 +694,7 @@ class Migration(migrations.Migration):
                 ),
                 (
                     "user_credentials",
-                    jsonfield.fields.JSONField(
-                        blank=True, null=True, verbose_name="PDF"
-                    ),
+                    models.JSONField(blank=True, null=True, verbose_name="PDF"),
                 ),
                 (
                     "expiration_date",