Limit decoders selection to model manufacturers

ram/metadata/migrations/0002_alter_decoder_manufacturer.py

@@ -0,0 +1,19 @@
+# Generated by Django 4.0.6 on 2022-07-10 21:46
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('metadata', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='decoder',
+            name='manufacturer',
+            field=models.ForeignKey(limit_choices_to={'category': 'model'}, on_delete=django.db.models.deletion.CASCADE, to='metadata.manufacturer'),
+        ),
+    ]

ram/metadata/models.py

@@ -59,7 +59,11 @@ class Company(models.Model):
 
 class Decoder(models.Model):
     name = models.CharField(max_length=128, unique=True)
-    manufacturer = models.ForeignKey(Manufacturer, on_delete=models.CASCADE)
+    manufacturer = models.ForeignKey(
+        Manufacturer,
+        on_delete=models.CASCADE,
+        limit_choices_to={"category": "model"}
+    )
     version = models.CharField(max_length=64, blank=True)
     interface = models.PositiveSmallIntegerField(
         choices=settings.DECODER_INTERFACES, null=True, blank=True