Add "accepted" flag to Activity, which is a special case for Follows. Seems a bit hacky, though.

f_type becomes a CharField, because it was a URLField, which is blatantly wrong.

Activity now has the relevant properties to make it able to consider itself as an object type.

django_kepi/migrations/0003_auto_20180918_1708.py

@@ -0,0 +1,23 @@
+# Generated by Django 2.1 on 2018-09-18 17:08
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_kepi', '0002_auto_20180916_1457'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='activity',
+            name='accepted',
+            field=models.BooleanField(default=False),
+        ),
+        migrations.AlterField(
+            model_name='activity',
+            name='f_type',
+            field=models.CharField(choices=[('C', 'Create'), ('U', 'Update'), ('D', 'Delete'), ('F', 'Follow'), ('+', 'Add'), ('-', 'Remove'), ('L', 'Like'), ('U', 'Undo'), ('A', 'Accept'), ('R', 'Reject')], max_length=1),
+        ),
+    ]

django_kepi/models.py

@@ -1,5 +1,5 @@
 from django.db import models
-from django_kepi import object_type_registry, resolve, NeedToFetchException
+from django_kepi import object_type_registry, resolve, NeedToFetchException, register_type
 from django.contrib.contenttypes.fields import GenericForeignKey
 from django.contrib.contenttypes.models import ContentType
 from django.conf import settings
@@ -112,7 +112,7 @@ class Activity(models.Model):
             (REJECT, 'Reject'),
             )
 
-    f_type = models.URLField(
+    f_type = models.CharField(
             max_length=1,
             choices=ACTIVITY_TYPE_CHOICES,
             )
@@ -147,6 +147,10 @@ class Activity(models.Model):
             default=True,
             )
 
+    accepted = models.BooleanField(
+            default=False,
+            )
+
     # XXX Updates from clients are partial,
     # but updates from remote sites are total.
     # We don't currently let clients create Activities,
@@ -166,6 +170,14 @@ class Activity(models.Model):
                 )
         return result
 
+    @property
+    def activity_id(self):
+        return self.identifier
+
+    @property
+    def activity_type(self):
+        return self.f_type
+
     @property
     def activity(self):
         result = {
@@ -197,10 +209,19 @@ class Activity(models.Model):
             'Remove': (True,  False,  True),
             'Like':   (True,  True,   False),
             'Undo':   (False, True,   False),
-            'Accept': (False, True,   False),
-            'Reject': (False, True,   False),
+            'Accept': (True,  True,   False),
+            'Reject': (True,  True,   False),
             }
 
+    @classmethod
+    def register_all_activity_types(cls):
+        for t in cls.TYPES.keys():
+            register_type(t, cls)
+
+    @classmethod
+    def find_activity(cls, url):
+        return cls.objects.get(identifier=url)
+
     @classmethod
     def create(cls, value,
             local=False):
@@ -300,3 +321,5 @@ class Activity(models.Model):
     # TODO: there should be a clean() method with the same
     # checks as create().
 
+Activity.register_all_activity_types()
+