Add field to segment to store excluded users

src/wagtail_personalisation/migrations/0018_segment_excluded_users.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.9 on 2018-02-09 08:28
+from __future__ import unicode_literals
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('wagtail_personalisation', '0017_segment_randomisation_percent'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='segment',
+            name='excluded_users',
+            field=models.ManyToManyField(help_text='Users that matched the rules but were excluded from the segment for some reason e.g. randomisation', related_name='excluded_segments', to=settings.AUTH_USER_MODEL),
+        ),
+    ]

src/wagtail_personalisation/models.py

@@ -83,6 +83,12 @@ class Segment(ClusterableModel):
     static_users = models.ManyToManyField(
         settings.AUTH_USER_MODEL,
     )
+    excluded_users = models.ManyToManyField(
+        settings.AUTH_USER_MODEL,
+        help_text=_("Users that matched the rules but were excluded from the "
+                    "segment for some reason e.g. randomisation"),
+        related_name="excluded_segments"
+    )
 
     matched_users_count = models.PositiveIntegerField(default=0, editable=False)
     matched_count_updated_at = models.DateTimeField(null=True, editable=False)