Update FrontPort model form

netbox/dcim/api/serializers_/device_components.py

@@ -333,14 +333,14 @@ class FrontPortSerializer(NetBoxModelSerializer, CabledObjectSerializer):
         allow_null=True
     )
     type = ChoiceField(choices=PortTypeChoices)
-    rear_port = FrontPortRearPortSerializer()
+    rear_ports = FrontPortRearPortSerializer(many=True)
 
     class Meta:
         model = FrontPort
         fields = [
             'id', 'url', 'display_url', 'display', 'device', 'module', 'name', 'label', 'type', 'color', 'positions',
-            'description', 'mark_connected', 'cable', 'cable_end', 'link_peers', 'link_peers_type', 'tags',
-            'custom_fields', 'created', 'last_updated', '_occupied',
+            'rear_ports', 'description', 'mark_connected', 'cable', 'cable_end', 'link_peers', 'link_peers_type',
+            'tags', 'custom_fields', 'created', 'last_updated', '_occupied',
         ]
         brief_fields = ('id', 'url', 'display', 'device', 'name', 'description', 'cable', '_occupied')
 

netbox/dcim/forms/model_forms.py

@@ -1578,16 +1578,15 @@ class InterfaceForm(InterfaceCommonForm, ModularDeviceComponentForm):
 
 
 class FrontPortForm(ModularDeviceComponentForm):
-    rear_port = DynamicModelChoiceField(
-        queryset=RearPort.objects.all(),
-        query_params={
-            'device_id': '$device',
-        }
+    rear_ports = forms.MultipleChoiceField(
+        choices=[],
+        label=_('Rear ports'),
+        widget=forms.SelectMultiple(attrs={'size': 6})
     )
 
     fieldsets = (
         FieldSet(
-            'device', 'module', 'name', 'label', 'type', 'color', 'rear_port', 'rear_port_position', 'mark_connected',
+            'device', 'module', 'name', 'label', 'type', 'color', 'positions', 'rear_ports', 'mark_connected',
             'description', 'tags',
         ),
     )
@@ -1599,6 +1598,59 @@ class FrontPortForm(ModularDeviceComponentForm):
             'tags',
         ]
 
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        if device_id := (self.data.get('device') or self.initial.get('device')):
+            device = Device.objects.get(pk=device_id)
+        else:
+            return
+
+        # Populate rear port choices
+        choices = []
+        for rear_port in RearPort.objects.filter(device=device):
+            for i in range(1, rear_port.positions + 1):
+                choices.append(
+                    ('{}:{}'.format(rear_port.pk, i), '{}:{}'.format(rear_port.name, i))
+                )
+        self.fields['rear_ports'].choices = choices
+
+        # Set initial rear port assignments
+        if self.instance.pk:
+            self.initial['rear_ports'] = [
+                f'{assignment.rear_port_id}:{assignment.rear_port_position}'
+                for assignment in PortAssignment.objects.filter(front_port_id=self.instance.pk)
+            ]
+
+    def clean(self):
+
+        # Count of selected rear port & position pairs much match the assigned number of positions
+        if len(self.cleaned_data['rear_ports']) != self.cleaned_data['positions']:
+            raise forms.ValidationError(
+                _("The number of rear port/position pairs selected must match the number of positions assigned.")
+            )
+
+    def _save_m2m(self):
+        super()._save_m2m()
+
+        # TODO: Can this be made more efficient?
+        # Delete existing rear port assignments
+        PortAssignment.objects.filter(front_port_id=self.instance.pk).delete()
+
+        # Create new rear port assignments
+        assignments = []
+        for i, rp_position in enumerate(self.cleaned_data['rear_ports'], start=1):
+            rear_port_id, rear_port_position = rp_position.split(':')
+            assignments.append(
+                PortAssignment(
+                    front_port_id=self.instance.pk,
+                    front_port_position=i,
+                    rear_port_id=rear_port_id,
+                    rear_port_position=rear_port_position,
+                )
+            )
+        PortAssignment.objects.bulk_create(assignments)
+
 
 class RearPortForm(ModularDeviceComponentForm):
     fieldsets = (

netbox/dcim/migrations/0222_frontport_positions.py

@@ -9,6 +9,10 @@ class Migration(migrations.Migration):
     ]
 
     operations = [
+        migrations.RemoveConstraint(
+            model_name='frontport',
+            name='dcim_frontport_unique_rear_port_position',
+        ),
         migrations.RemoveField(
             model_name='frontport',
             name='rear_port',

netbox/dcim/models/device_components.py

@@ -35,6 +35,7 @@ __all__ = (
     'InventoryItemRole',
     'ModuleBay',
     'PathEndpoint',
+    'PortAssignment',
     'PowerOutlet',
     'PowerPort',
     'RearPort',
@@ -1106,6 +1107,29 @@ class PortAssignment(models.Model):
             ),
         )
 
+    def clean(self):
+
+        # Validate rear port assignment
+        if self.front_port.device_id != self.rear_port.device_id:
+            raise ValidationError({
+                "rear_port": _("Rear port ({rear_port}) must belong to the same device").format(
+                    rear_port=self.rear_port
+                )
+            })
+
+        # Validate rear port position assignment
+        if self.rear_port_position > self.rear_port.positions:
+            raise ValidationError({
+                "rear_port_position": _(
+                    "Invalid rear port position ({rear_port_position}): Rear port {name} has only {positions} "
+                    "positions."
+                ).format(
+                    rear_port_position=self.rear_port_position,
+                    name=self.rear_port.name,
+                    positions=self.rear_port.positions
+                )
+            })
+
 
 class FrontPort(ModularComponentModel, CabledObjectModel, TrackingModelMixin):
     """
@@ -1142,40 +1166,10 @@ class FrontPort(ModularComponentModel, CabledObjectModel, TrackingModelMixin):
                 fields=('device', 'name'),
                 name='%(app_label)s_%(class)s_unique_device_name'
             ),
-            models.UniqueConstraint(
-                fields=('rear_port', 'rear_port_position'),
-                name='%(app_label)s_%(class)s_unique_rear_port_position'
-            ),
         )
         verbose_name = _('front port')
         verbose_name_plural = _('front ports')
 
-    def clean(self):
-        super().clean()
-
-        if hasattr(self, 'rear_port'):
-
-            # Validate rear port assignment
-            if self.rear_port.device != self.device:
-                raise ValidationError({
-                    "rear_port": _(
-                        "Rear port ({rear_port}) must belong to the same device"
-                    ).format(rear_port=self.rear_port)
-                })
-
-            # Validate rear port position assignment
-            if self.rear_port_position > self.rear_port.positions:
-                raise ValidationError({
-                    "rear_port_position": _(
-                        "Invalid rear port position ({rear_port_position}): Rear port {name} has only {positions} "
-                        "positions."
-                    ).format(
-                        rear_port_position=self.rear_port_position,
-                        name=self.rear_port.name,
-                        positions=self.rear_port.positions
-                    )
-                })
-
 
 class RearPort(ModularComponentModel, CabledObjectModel, TrackingModelMixin):
     """

netbox/dcim/views.py

@@ -42,6 +42,7 @@ from wireless.models import WirelessLAN
 from . import filtersets, forms, tables
 from .choices import DeviceFaceChoices, InterfaceModeChoices
 from .models import *
+from .models.device_components import PortAssignment
 from .object_actions import BulkAddComponents, BulkDisconnect
 
 CABLE_TERMINATION_TYPES = {
@@ -3242,6 +3243,11 @@ class FrontPortListView(generic.ObjectListView):
 class FrontPortView(generic.ObjectView):
     queryset = FrontPort.objects.all()
 
+    def get_extra_context(self, request, instance):
+        return {
+            'rear_port_assignments': PortAssignment.objects.filter(front_port=instance).prefetch_related('rear_port'),
+        }
+
 
 @register_model_view(FrontPort, 'add', detail=False)
 class FrontPortCreateView(generic.ComponentCreateView):
@@ -3313,6 +3319,11 @@ class RearPortListView(generic.ObjectListView):
 class RearPortView(generic.ObjectView):
     queryset = RearPort.objects.all()
 
+    def get_extra_context(self, request, instance):
+        return {
+            'front_port_assignments': PortAssignment.objects.filter(rear_port=instance).prefetch_related('front_port'),
+        }
+
 
 @register_model_view(RearPort, 'add', detail=False)
 class RearPortCreateView(generic.ComponentCreateView):

netbox/templates/dcim/frontport.html

@@ -61,6 +61,18 @@
             {% plugin_left_page object %}
         </div>
         <div class="col col-12 col-md-6">
+            <div class="card">
+                <h2 class="card-header">{% trans "Rear Ports" %}</h2>
+                <table class="table table-hover">
+                  {% for assignment in rear_port_assignments %}
+                    <tr>
+                      <td>{{ assignment.front_port_position }}</td>
+                      <td>{{ assignment.rear_port|linkify }}</td>
+                      <td>{{ assignment.rear_port_position }}</td>
+                    </tr>
+                  {% endfor %}
+                </table>
+            </div>
             <div class="card">
                 <h2 class="card-header">{% trans "Connection" %}</h2>
                 {% if object.mark_connected %}

netbox/templates/dcim/rearport.html

@@ -61,6 +61,18 @@
             {% plugin_left_page object %}
         </div>
         <div class="col col-12 col-md-6">
+            <div class="card">
+                <h2 class="card-header">{% trans "Rear Ports" %}</h2>
+                <table class="table table-hover">
+                  {% for assignment in front_port_assignments %}
+                    <tr>
+                      <td>{{ assignment.rear_port_position }}</td>
+                      <td>{{ assignment.front_port|linkify }}</td>
+                      <td>{{ assignment.front_port_position }}</td>
+                    </tr>
+                  {% endfor %}
+                </table>
+            </div>
             <div class="card">
                 <h2 class="card-header">{% trans "Connection" %}</h2>
                 {% if object.mark_connected %}