changed database rules so that deleting Users does not delete Organisation and Person objects

3 files changed, 59 insertions, 3 deletions

diff --git a/ctrack/organisations/migrations/0003_auto_20200220_1625.py b/ctrack/organisations/migrations/0003_auto_20200220_1625.py
new file mode 100644
index 0000000..65f4478
--- /dev/null
+++ b/ctrack/organisations/migrations/0003_auto_20200220_1625.py
@@ -0,0 +1,20 @@
+# Generated by Django 2.2.9 on 2020-02-20 16:25
+
+import ctrack.organisations.models
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('organisations', '0002_auto_20200220_1434'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='organisation',
+            name='updated_by',
+            field=models.ForeignKey(on_delete=models.SET(ctrack.organisations.models.Organisation.get_sentinel_user), to=settings.AUTH_USER_MODEL),
+        ),
+    ]
diff --git a/ctrack/organisations/migrations/0004_auto_20200220_1634.py b/ctrack/organisations/migrations/0004_auto_20200220_1634.py
new file mode 100644
index 0000000..297931e
--- /dev/null
+++ b/ctrack/organisations/migrations/0004_auto_20200220_1634.py
@@ -0,0 +1,20 @@
+# Generated by Django 2.2.9 on 2020-02-20 16:34
+
+import ctrack.organisations.models
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('organisations', '0003_auto_20200220_1625'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='person',
+            name='updated_by',
+            field=models.ForeignKey(on_delete=models.SET(ctrack.organisations.models.Person.get_sentinel_user), to=settings.AUTH_USER_MODEL),
+        ),
+    ]
diff --git a/ctrack/organisations/models.py b/ctrack/organisations/models.py
index a04fa32..13023a0 100644
--- a/ctrack/organisations/models.py
+++ b/ctrack/organisations/models.py
@@ -43,6 +43,15 @@ class Person(models.Model):
         (5, "DV"),
         (6, "Other"),
     ]
+
+    def get_sentinel_user():
+        """
+        We need this so that we can ensure models.SET() is applied with a callable
+        to handle when Users are deleted from the system, preventing the Person objects
+        related to them being deleted also.
+        """
+        return get_user_model().objects.get_or_create(username='DELETED USER')[0]
+
     primary_nis_contact = models.BooleanField(
         default=False, verbose_name="Primary NIS contact"
     )
@@ -59,7 +68,7 @@ class Person(models.Model):
     mobile = models.CharField(max_length=20, blank=True)
     landline = models.CharField(max_length=20, blank=True)
     date_updated = models.DateField(auto_now=True)
-    updated_by = models.ForeignKey(get_user_model(), on_delete=models.CASCADE)
+    updated_by = models.ForeignKey(get_user_model(), on_delete=models.SET(get_sentinel_user))
     clearance = models.IntegerField(choices=CLEARANCE_LEVEL, default=1)
     clearance_sponsor = models.CharField(max_length=100, blank=True)
     clearance_start_date = models.DateField(blank=True, null=True)
@@ -98,12 +107,19 @@ class Submode(models.Model):
 
 
 class Organisation(models.Model):
-
     DESIGNATION_TYPE = [
         (1, "Automatic"),
         (2, "Reserve Power"),
     ]
 
+    def get_sentinel_user():
+        """
+        We need this so that we can ensure models.SET() is applied with a callable
+        to handle when Users are deleted from the system, preventing the Organisations
+        related to them being deleted also.
+        """
+        return get_user_model().objects.get_or_create(username='DELETED USER')[0]
+
     name = models.CharField(max_length=255)
     slug = AutoSlugField(populate_from=["name"])
     submode = models.ForeignKey(
@@ -113,7 +129,7 @@ class Organisation(models.Model):
     registered_company_name = models.CharField(max_length=255, blank=True)
     registered_company_number = models.CharField(max_length=100, blank=True)
     date_updated = models.DateField(auto_now=True)
-    updated_by = models.ForeignKey(get_user_model(), on_delete=models.CASCADE)
+    updated_by = models.ForeignKey(get_user_model(), on_delete=models.SET(get_sentinel_user))
     comments = models.TextField(max_length=500)
     active = models.BooleanField(default=True)