fix!(models): modify on_delete behaviour for instrument, avresource, …

…instrumentname models

- On the Instrument model, set default_image and thumbnail to NULL if related
AVResource object is deleted.
- On the InstrumentName model, delete the InstrumentName if the related Instrument
is deleted.
- On the AVResource model, set the instrument field to NULL if the related Instrument
is deleted.

web-app/django/VIM/apps/instruments/migrations/0003_alter_avresource_instrument_and_more.py

@@ -0,0 +1,34 @@
+# Generated by Django 4.2.5 on 2024-08-14 22:18
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('instruments', '0002_instrument_thumbnail'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='avresource',
+            name='instrument',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, to='instruments.instrument'),
+        ),
+        migrations.AlterField(
+            model_name='instrument',
+            name='default_image',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='default_image_of', to='instruments.avresource'),
+        ),
+        migrations.AlterField(
+            model_name='instrument',
+            name='thumbnail',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='thumbnail_of', to='instruments.avresource'),
+        ),
+        migrations.AlterField(
+            model_name='instrumentname',
+            name='instrument',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='instruments.instrument'),
+        ),
+    ]

web-app/django/VIM/apps/instruments/models/avresource.py

@@ -8,7 +8,7 @@ class AVResource(models.Model):
         ("image", "Image"),
     ]
 
-    instrument = models.ForeignKey("Instrument", on_delete=models.PROTECT)
+    instrument = models.ForeignKey("Instrument", on_delete=models.SET_NULL, null=True)
     type = models.CharField(
         max_length=5,
         choices=RESOURCE_TYPE_CHOICES,

web-app/django/VIM/apps/instruments/models/instrument.py

@@ -5,14 +5,14 @@ class Instrument(models.Model):
     wikidata_id = models.CharField(max_length=20, unique=True)
     default_image = models.ForeignKey(
         "AVResource",
-        on_delete=models.PROTECT,
+        on_delete=models.SET_NULL,
         blank=True,
         null=True,
         related_name="default_image_of",
     )
     thumbnail = models.ForeignKey(
         "AVResource",
-        on_delete=models.PROTECT,
+        on_delete=models.SET_NULL,
         blank=True,
         null=True,
         related_name="thumbnail_of",

web-app/django/VIM/apps/instruments/models/instrument_name.py

@@ -2,7 +2,7 @@
 
 
 class InstrumentName(models.Model):
-    instrument = models.ForeignKey("Instrument", on_delete=models.PROTECT)
+    instrument = models.ForeignKey("Instrument", on_delete=models.CASCADE)
     language = models.ForeignKey("Language", on_delete=models.PROTECT)
     name = models.CharField(max_length=50, blank=False)
     source_name = models.CharField(