Fixed lambda serialization error

source/lostplaces/lostplaces_app/migrations/0005_auto_20200728_0738.py

@@ -0,0 +1,20 @@
+# Generated by Django 3.0.8 on 2020-07-28 07:38
+
+from django.db import migrations
+import django_thumbs.fields
+import lostplaces_app.models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('lostplaces_app', '0004_auto_20200727_1803'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='placeimage',
+            name='filename',
+            field=django_thumbs.fields.ImageThumbsField(max_length=50, sizes=({'code': 'thumbnail', 'wxh': '390x390'}, {'code': 'hero', 'wxh': '700x700'}, {'code': 'large', 'wxh': '1920x1920'}), upload_to=lostplaces_app.models.generate_image_upload_path),
+        ),
+    ]

source/lostplaces/lostplaces_app/models.py

@@ -17,9 +17,12 @@ class Place (models.Model):
     def __str__(self):
         return self.name
 
+def generate_image_upload_path(instance, filename):
+    return 'places/' + str(uuid.uuid4())+'.'+filename.split('.')[-1]
+
 class PlaceImage (models.Model):
     filename = ImageThumbsField(
-        upload_to=lambda instance, filename: 'places/' + str(uuid.uuid4())+'.'+filename.split('.')[-1],
+        upload_to=generate_image_upload_path,
         max_length=50,
         sizes = (
             {'code': 'thumbnail', 'wxh': '390x390'},