Move decoder interface def into rolling stock

ram/roster/admin.py

@@ -148,6 +148,7 @@ class RollingStockAdmin(admin.ModelAdmin):
             "DCC",
             {
                 "fields": (
+                    "decoder_interface",
                     "decoder",
                     "address",
                 )

ram/roster/migrations/0013_rollingstock_decoder_interface.py

@@ -0,0 +1,42 @@
+# Generated by Django 4.1 on 2022-10-31 22:27
+
+from django.db import migrations, models
+
+
+def meta_to_roster(apps, schema_editor):
+    model = apps.get_model("roster", "RollingStock")
+
+    for row in model.objects.all():
+        if row.decoder:
+            decoder_interface = row.decoder.interface
+            row.__dict__["decoder_interface"] = decoder_interface
+            row.save(update_fields=["decoder_interface"])
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("roster", "0012_rollingstockjournal"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="rollingstock",
+            name="decoder_interface",
+            field=models.PositiveSmallIntegerField(
+                blank=True,
+                choices=[
+                    (1, "NEM651"),
+                    (2, "NEM652"),
+                    (3, "PluX"),
+                    (4, "21MTC"),
+                    (5, "Next18/Next18S"),
+                ],
+                null=True,
+            ),
+        ),
+        migrations.RunPython(
+            meta_to_roster,
+            reverse_code=migrations.RunPython.noop
+        ),
+    ]

ram/roster/models.py

@@ -3,6 +3,7 @@ import re
 from uuid import uuid4
 from django.db import models
 from django.urls import reverse
+from django.conf import settings
 from django.dispatch import receiver
 from django.utils.safestring import mark_safe
 
@@ -87,6 +88,9 @@ class RollingStock(models.Model):
     )
     scale = models.ForeignKey(Scale, on_delete=models.CASCADE)
     sku = models.CharField(max_length=32, blank=True)
+    decoder_interface = models.PositiveSmallIntegerField(
+        choices=settings.DECODER_INTERFACES, null=True, blank=True
+    )
     decoder = models.ForeignKey(
         Decoder, on_delete=models.CASCADE, null=True, blank=True
     )