calculate qrcode_base64 on the fly

src/tickets/migrations/0003_auto_20170819_2309.py

@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.5 on 2017-08-19 21:09
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('tickets', '0002_auto_20170819_2222'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='discountticket',
+            name='qrcode_base64',
+        ),
+        migrations.RemoveField(
+            model_name='shopticket',
+            name='qrcode_base64',
+        ),
+        migrations.RemoveField(
+            model_name='sponsorticket',
+            name='qrcode_base64',
+        ),
+    ]

src/tickets/models.py

@@ -28,17 +28,12 @@ class TicketType(CreatedUpdatedModel, UUIDModel):
 
 
 class BaseTicket(CreatedUpdatedModel, UUIDModel):
-    qrcode_base64 = models.TextField(null=True, blank=True)
     ticket_type = models.ForeignKey('TicketType')
     checked_in = models.BooleanField(default=False)
 
     class Meta:
         abstract = True
 
-    def save(self, **kwargs):
-        self.qrcode_base64 = self.get_qr_code()
-        super().save(**kwargs)
-
     def _get_token(self):
         return hashlib.sha256(
             '{_id}{secret_key}'.format(
@@ -47,7 +42,7 @@ class BaseTicket(CreatedUpdatedModel, UUIDModel):
             ).encode('utf-8')
         ).hexdigest()
 
-    def get_qr_code(self):
+    def get_qr_code_base64(self):
         qr = qrcode.make(
             self._get_token(),
             version=1,
@@ -59,7 +54,7 @@ class BaseTicket(CreatedUpdatedModel, UUIDModel):
         return qrcode_base64
 
     def get_qr_code_url(self):
-        return 'data:image/png;base64,{}'.format(self.qrcode_base64)
+        return 'data:image/png;base64,{}'.format(self.get_qr_code_base64)
 
     def generate_pdf(self):
         generate_pdf_letter(