Refactor DCIM forms

netbox/dcim/forms/formsets.py

@@ -0,0 +1,21 @@
+from django import forms
+
+__all__ = (
+    'BaseVCMemberFormSet',
+)
+
+
+class BaseVCMemberFormSet(forms.BaseModelFormSet):
+
+    def clean(self):
+        super().clean()
+
+        # Check for duplicate VC position values
+        vc_position_list = []
+        for form in self.forms:
+            vc_position = form.cleaned_data.get('vc_position')
+            if vc_position:
+                if vc_position in vc_position_list:
+                    error_msg = f"A virtual chassis member already exists in position {vc_position}."
+                    form.add_error('vc_position', error_msg)
+                vc_position_list.append(vc_position)