improve importer

cookbook/migrations/0193_unitconversion_f_unique_conversion_per_space.py

@@ -0,0 +1,17 @@
+# Generated by Django 4.1.7 on 2023-05-04 05:57
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('cookbook', '0192_remove_foodpropertytype_fdc_id_and_more'),
+    ]
+
+    operations = [
+        migrations.AddConstraint(
+            model_name='unitconversion',
+            constraint=models.UniqueConstraint(fields=('space', 'base_unit', 'converted_unit', 'food'), name='f_unique_conversion_per_space'),
+        ),
+    ]