Provide model-level default function option

InvenTree/InvenTree/metadata.py

@@ -98,7 +98,7 @@ class InvenTreeMetadata(SimpleMetadata):
         Override get_serializer_info so that we can add 'default' values
         to any fields whose Meta.model specifies a default value
         """
-
+        
         serializer_info = super().get_serializer_info(serializer)
 
         model_class = None
@@ -108,6 +108,13 @@ class InvenTreeMetadata(SimpleMetadata):
 
             model_fields = model_meta.get_field_info(model_class)
 
+            model_default_func = getattr(model_class, 'api_defaults', None)
+
+            if model_default_func:
+                model_default_values = model_class.api_defaults(self.request)
+            else:
+                model_default_values = {}
+
             # Iterate through simple fields
             for name, field in model_fields.fields.items():
 
@@ -123,6 +130,9 @@ class InvenTreeMetadata(SimpleMetadata):
 
                     serializer_info[name]['default'] = default
 
+                elif name in model_default_values:
+                    serializer_info[name]['default'] = model_default_values[name]
+
             # Iterate through relations
             for name, relation in model_fields.relations.items():
 
@@ -141,6 +151,9 @@ class InvenTreeMetadata(SimpleMetadata):
                 if 'help_text' not in serializer_info[name] and hasattr(relation.model_field, 'help_text'):
                     serializer_info[name]['help_text'] = relation.model_field.help_text
 
+                if name in model_default_values:
+                    serializer_info[name]['default'] = model_default_values[name]
+
         except AttributeError:
             pass
 

InvenTree/build/models.py

@@ -47,7 +47,7 @@ def get_next_build_number():
     """
 
     if Build.objects.count() == 0:
-        return
+        return '0001'
 
     build = Build.objects.exclude(reference=None).last()
 
@@ -100,13 +100,28 @@ class Build(MPTTModel, ReferenceIndexingMixin):
         return reverse('api-build-list')
 
     def api_instance_filters(self):
-
+        
         return {
             'parent': {
                 'exclude_tree': self.pk,
             }
         }
 
+    @classmethod
+    def api_defaults(cls, request):
+        """
+        Return default values for this model when issuing an API OPTIONS request
+        """
+
+        defaults = {
+            'reference': get_next_build_number(),
+        }
+
+        if request and request.user:
+            defaults['issued_by'] = request.user.pk
+
+        return defaults
+
     def save(self, *args, **kwargs):
 
         self.rebuild_reference_field()

InvenTree/order/models.py

@@ -37,7 +37,7 @@ def get_next_po_number():
     """
 
     if PurchaseOrder.objects.count() == 0:
-        return
+        return '0001'
 
     order = PurchaseOrder.objects.exclude(reference=None).last()
 
@@ -66,7 +66,7 @@ def get_next_so_number():
     """
 
     if SalesOrder.objects.count() == 0:
-        return
+        return '0001'
 
     order = SalesOrder.objects.exclude(reference=None).last()