Closes #20564: Many-to-many pass-through port mappings (#20851)

netbox/dcim/api/serializers_/base.py

@@ -2,10 +2,12 @@ from drf_spectacular.types import OpenApiTypes
 from drf_spectacular.utils import extend_schema_field
 from rest_framework import serializers
 
+from dcim.models import FrontPort, FrontPortTemplate, PortMapping, PortTemplateMapping, RearPort, RearPortTemplate
 from utilities.api import get_serializer_for_model
 
 __all__ = (
     'ConnectedEndpointsSerializer',
+    'PortSerializer',
 )
 
 
@@ -35,3 +37,53 @@ class ConnectedEndpointsSerializer(serializers.ModelSerializer):
     @extend_schema_field(serializers.BooleanField)
     def get_connected_endpoints_reachable(self, obj):
         return obj._path and obj._path.is_complete and obj._path.is_active
+
+
+class PortSerializer(serializers.ModelSerializer):
+    """
+    Base serializer for front & rear port and port templates.
+    """
+    @property
+    def _mapper(self):
+        """
+        Return the model and ForeignKey field name used to track port mappings for this model.
+        """
+        if self.Meta.model is FrontPort:
+            return PortMapping, 'front_port'
+        if self.Meta.model is RearPort:
+            return PortMapping, 'rear_port'
+        if self.Meta.model is FrontPortTemplate:
+            return PortTemplateMapping, 'front_port'
+        if self.Meta.model is RearPortTemplate:
+            return PortTemplateMapping, 'rear_port'
+        raise ValueError(f"Could not determine mapping details for {self.__class__}")
+
+    def create(self, validated_data):
+        mappings = validated_data.pop('mappings', [])
+        instance = super().create(validated_data)
+
+        # Create port mappings
+        mapping_model, fk_name = self._mapper
+        for attrs in mappings:
+            mapping_model.objects.create(**{
+                fk_name: instance,
+                **attrs,
+            })
+
+        return instance
+
+    def update(self, instance, validated_data):
+        mappings = validated_data.pop('mappings', None)
+        instance = super().update(instance, validated_data)
+
+        if mappings is not None:
+            # Update port mappings
+            mapping_model, fk_name = self._mapper
+            mapping_model.objects.filter(**{fk_name: instance}).delete()
+            for attrs in mappings:
+                mapping_model.objects.create(**{
+                    fk_name: instance,
+                    **attrs,
+                })
+
+        return instance