modify the credentials_version_hash migration to create hashes for re…

…cent attempts

apps/sushi/migrations/0028_sushifetchattempt_credentials_version_hash.py

@@ -1,6 +1,40 @@
 # Generated by Django 2.2.12 on 2020-05-22 13:38
+import json
+from hashlib import blake2b
 
-from django.db import migrations, models
+from django.db import migrations
+from django.db import models
+from django.db.models import F
+
+
+def get_hash(credentials):
+    keys = {
+        'url',
+        'counter_version',
+        'requestor_id',
+        'customer_id',
+        'http_username',
+        'http_password',
+        'api_key',
+        'extra_params',
+    }
+    data = {key: getattr(credentials, key) for key in keys}
+    dump = json.dumps(data, ensure_ascii=False, sort_keys=True)
+    return blake2b(dump.encode('utf-8'), digest_size=16).hexdigest()
+
+
+def fill_credentials_version_hash(apps, schema_editor):
+    SushiFetchAttempt = apps.get_model('sushi', 'SushiFetchAttempt')
+    for fa in SushiFetchAttempt.objects.filter(
+        timestamp__gte=F('credentials__last_updated')
+    ).select_related('credentials'):
+        fa.credentials_version_hash = get_hash(fa.credentials)
+        fa.save()
+
+
+def reverse(apps, schema_editor):
+    SushiFetchAttempt = apps.get_model('sushi', 'SushiFetchAttempt')
+    SushiFetchAttempt.objects.all().update(credentials_version_hash='')
 
 
 class Migration(migrations.Migration):
@@ -20,4 +54,8 @@ class Migration(migrations.Migration):
             ),
             preserve_default=False,
         ),
+        # we are adding the hash of the credentials to attempts based on the last_updated
+        # date of the credentials. Therefore we need to add it before the credentials
+        # is modified by adding its hash
+        migrations.RunPython(fill_credentials_version_hash, reverse),
     ]