Merged in [17992] from rjsparks@nostrum.com:

Improve admin form validation for used_roles.
 - Legacy-Id: 17996
Note: SVN reference [17992] has been migrated to Git commit c69556efe1

ietf/group/admin.py

@@ -4,6 +4,8 @@
 
 from functools import update_wrapper
 
+from django import forms
+
 from django.contrib import admin
 from django.contrib.admin.utils import unquote
 from django.core.exceptions import PermissionDenied
@@ -25,7 +27,20 @@ class RoleInline(admin.TabularInline):
 class GroupURLInline(admin.TabularInline):
     model = GroupURL
 
+class GroupForm(forms.ModelForm):
+    class Meta:
+        model = Group
+        fields = '__all__'
+
+    def clean_used_roles(self):
+        data = self.cleaned_data['used_roles']
+        if data is None or data == '':
+            raise forms.ValidationError("Must contain a valid json expression. To use the defaults prove an empty list: []")
+        return data
+            
+
 class GroupAdmin(admin.ModelAdmin):
+    form = GroupForm
     list_display = ["acronym", "name", "type", "state", "time", "role_list"]
     list_display_links = ["acronym", "name"]
     list_filter = ["type", "state", "time"]

ietf/group/migrations/0031_allow_blank_used_roles.py

@@ -0,0 +1,24 @@
+# Generated by Django 2.0.13 on 2020-06-15 11:10
+
+from django.db import migrations
+import jsonfield.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('group', '0030_populate_default_used_roles'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='group',
+            name='used_roles',
+            field=jsonfield.fields.JSONField(blank=True, default=[], help_text="Leave an empty list to get the group_type's default used roles", max_length=128),
+        ),
+        migrations.AlterField(
+            model_name='grouphistory',
+            name='used_roles',
+            field=jsonfield.fields.JSONField(blank=True, default=[], help_text="Leave an empty list to get the group_type's default used roles", max_length=128),
+        ),
+    ]

ietf/group/models.py

@@ -43,7 +43,7 @@ class GroupInfo(models.Model):
     unused_states = models.ManyToManyField('doc.State', help_text="Document states that have been disabled for the group.", blank=True)
     unused_tags = models.ManyToManyField(DocTagName, help_text="Document tags that have been disabled for the group.", blank=True)
 
-    used_roles = jsonfield.JSONField(max_length=128, blank=False, default=[], help_text="Leave an empty list to get the group_type's default used roles")
+    used_roles = jsonfield.JSONField(max_length=128, blank=True, default=[], help_text="Leave an empty list to get the group_type's default used roles")
 
     uses_milestone_dates = models.BooleanField(default=True)