Fixed model conversion logic if property is not column

flask_admin/contrib/sqlamodel/form.py

@@ -79,6 +79,11 @@ class AdminModelConverter(ModelConverterBase):
         else:
             # Ignore pk/fk
             if hasattr(prop, 'columns'):
+                # Check if more than one column mapped to the property
+                if len(prop.columns) != 1:
+                    raise TypeError('Can not convert multiple-column properties (%s.%s)' % (model, prop.key))
+
+                # Grab column
                 column = prop.columns[0]
 
                 # Do not display foreign keys - use relations
@@ -113,10 +118,6 @@ class AdminModelConverter(ModelConverterBase):
                 # Apply label
                 kwargs['label'] = self._get_label(prop.key, kwargs)
 
-            # Check if more than one column mapped to the property
-            if len(prop.columns) != 1:
-                raise TypeError('Can not convert multiple-column properties (%s.%s)' % (model, prop.key))
-
                 # Figure out default value
                 default = getattr(column, 'default', None)
 
@@ -147,6 +148,8 @@ class AdminModelConverter(ModelConverterBase):
                 return converter(model=model, mapper=mapper, prop=prop,
                                 column=column, field_args=kwargs)
 
+        return None
+
     @classmethod
     def _string_common(cls, column, field_args, **extra):
         if column.type.length: