Add fields to serializer to resolve source / target refs

InvenTree/InvenTree/helpers.py

@@ -696,3 +696,43 @@ def clean_decimal(number):
         return Decimal(0)
 
     return clean_number.quantize(Decimal(1)) if clean_number == clean_number.to_integral() else clean_number.normalize()
+
+
+def get_objectreference(obj, type_ref: str = 'content_type', object_ref: str = 'object_id'):
+    """lookup method for the GenericForeignKey fields
+    
+    Attributes:
+    - obj: object that will be resolved
+    - type_ref: field name for the contenttype field in the model
+    - object_ref: field name for the object id in the model
+
+    Example implementation in the serializer:
+    ```
+    target = serializers.SerializerMethodField()
+    def get_target(self, obj):
+        return get_objectreference(obj, 'target_content_type', 'target_object_id')
+    ```
+
+    The method name must always be the name of the field prefixed by 'get_'
+    """
+    model_cls = getattr(obj, type_ref)
+    obj_id = getattr(obj, object_ref)
+
+    # check if references are set -> return nothing if not
+    if model_cls is None or obj_id is None:
+        return None
+
+    # resolve referenced data into objects
+    model_cls = model_cls.model_class()
+    item = model_cls.objects.get(id=obj_id)
+    url_fnc = getattr(item, 'get_absolute_url', None)
+
+    # create output
+    ret = {}
+    if url_fnc:
+        ret['link'] = url_fnc()
+    return {
+        'name': str(item),
+        'model': str(model_cls._meta.verbose_name),
+        **ret
+    }

InvenTree/common/serializers.py

@@ -6,6 +6,7 @@ JSON serializers for common components
 from __future__ import unicode_literals
 
 from InvenTree.serializers import InvenTreeModelSerializer
+from InvenTree.helpers import get_objectreference
 
 from rest_framework import serializers
 
@@ -102,7 +103,9 @@ class NotificationMessageSerializer(SettingsSerializer):
     Serializer for the InvenTreeUserSetting model
     """
 
-    #content_object = serializers.PrimaryKeyRelatedField(read_only=True)
+    target = serializers.SerializerMethodField()
+
+    source = serializers.SerializerMethodField()
 
     user = serializers.PrimaryKeyRelatedField(read_only=True)
 
@@ -120,11 +123,18 @@ class NotificationMessageSerializer(SettingsSerializer):
 
     read = serializers.BooleanField()
 
+    def get_target(self, obj):
+        return get_objectreference(obj, 'target_content_type', 'target_object_id')
+
+    def get_source(self, obj):
+        return get_objectreference(obj, 'source_content_type', 'source_object_id')
+
     class Meta:
         model = NotificationMessage
         fields = [
             'pk',
-            #'content_object',
+            'target',
+            'source',
             'user',
             'category',
             'name',