FIX: Prevent creating duplicate cable types

assets/forms.py

@@ -1,6 +1,7 @@
 from django import forms
 
 from assets import models
+from django.db.models import Q
 
 
 class AssetForm(forms.ModelForm):
@@ -40,3 +41,12 @@ class CableTypeForm(forms.ModelForm):
     class Meta:
         model = models.CableType
         fields = '__all__'
+
+    def clean(self):
+        form_data = self.cleaned_data
+        queryset = models.CableType.objects.filter(Q(plug=form_data['plug']) & Q(socket=form_data['socket']) & Q(circuits=form_data['circuits']) & Q(cores=form_data['cores']))
+        # Being identical to itself doesn't count...
+        print(self.instance.id)
+        if queryset.exists() and self.instance.pk != queryset[0].pk:
+            raise forms.ValidationError("A cable type that exactly matches this one already exists, please use that instead.", code="notunique")
+        return form_data