Add some more custom FileField serializers

(cherry picked from commit 7b9ff27baefacc977fef7852e99d8a9bb46a062a)

InvenTree/order/serializers.py

@@ -10,6 +10,8 @@ from rest_framework import serializers
 from django.db.models import Count
 
 from InvenTree.serializers import InvenTreeModelSerializer
+from InvenTree.serializers import InvenTreeAttachmentSerializerField
+
 from company.serializers import CompanyBriefSerializer, SupplierPartSerializer
 from part.serializers import PartBriefSerializer
 
@@ -112,6 +114,8 @@ class POAttachmentSerializer(InvenTreeModelSerializer):
     Serializers for the PurchaseOrderAttachment model
     """
 
+    attachment = InvenTreeAttachmentSerializerField()
+
     class Meta:
         model = PurchaseOrderAttachment
         
@@ -255,6 +259,8 @@ class SOAttachmentSerializer(InvenTreeModelSerializer):
     Serializers for the SalesOrderAttachment model
     """
 
+    attachment = InvenTreeAttachmentSerializerField()
+
     class Meta:
         model = SalesOrderAttachment