Make sure we don't upload the same file twice.

django_etesync/migrations/0010_auto_20200220_1248.py

@@ -0,0 +1,19 @@
+# Generated by Django 3.0.3 on 2020-02-20 12:48
+
+from django.db import migrations, models
+import django_etesync.models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_etesync', '0009_auto_20200220_1220'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='collectionitemchunk',
+            name='chunkFile',
+            field=models.FileField(max_length=150, unique=True, upload_to=django_etesync.models.chunk_directory_path),
+        ),
+    ]

django_etesync/models.py

@@ -65,7 +65,7 @@ class CollectionItemChunk(models.Model):
                            max_length=44, validators=[UidValidator])
     item = models.ForeignKey(CollectionItem, related_name='chunks', on_delete=models.CASCADE)
     order = models.CharField(max_length=100, blank=False, null=False)
-    chunkFile = models.FileField(upload_to=chunk_directory_path, max_length=150)
+    chunkFile = models.FileField(upload_to=chunk_directory_path, max_length=150, unique=True)
 
     class Meta:
         unique_together = ('item', 'order')