Allow null values for contact id on resource downloads

salesforce/migrations/0083_alter_resourcedownload_contact_id.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.4 on 2021-06-29 15:41
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('salesforce', '0082_partner_partnership_level'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='resourcedownload',
+            name='contact_id',
+            field=models.CharField(default='', max_length=100, null=True),
+        ),
+    ]

salesforce/migrations/0084_alter_resourcedownload_contact_id.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.4 on 2021-06-29 15:44
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('salesforce', '0083_alter_resourcedownload_contact_id'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='resourcedownload',
+            name='contact_id',
+            field=models.CharField(blank=True, max_length=100, null=True),
+        ),
+    ]

salesforce/models.py

@@ -331,7 +331,7 @@ class ResourceDownload(models.Model):
     last_access = models.DateTimeField()
     number_of_times_accessed = models.IntegerField()
     resource_name = models.CharField(max_length=255, null=True, blank=False)
-    contact_id = models.CharField(max_length=100, blank=True, default='')
+    contact_id = models.CharField(max_length=100, null=True, blank=True)
 
     def save(self, *args, **kwargs):
         if not self.pk: