configuration: add setting for product-categories

configuration.py

@@ -6,7 +6,7 @@
 
 
 from trytond.pool import PoolMeta
-from trytond.model import fields
+from trytond.model import fields, ModelSQL
 
 
 sel_number_target = [
@@ -29,6 +29,11 @@ class Configuration(metaclass=PoolMeta):
         string='Invoice number',
         help='Destination for the invoice number of the supplier invoice.',
         selection=sel_number_target)
+    product_category = fields.Many2Many(
+        string='Categories', origin='config', target='category',
+        help='Categories used to determine tax and accounts for a product ' +
+        'on an invoice line.',
+        relation_name='document.incoming.confprodcat_rel')
 
     @classmethod
     def default_number_target(cls):
@@ -58,3 +63,18 @@ class Configuration(metaclass=PoolMeta):
         return False
 
 # end Configuration
+
+
+class ConfigProductcategoryRel(ModelSQL):
+    'Configuration - Product Category - Relation'
+    __name__ = 'document.incoming.confprodcat_rel'
+
+    config = fields.Many2One(
+        string='Configuration', required=True,
+        ondelete='CASCADE', model_name='document.incoming.configuration')
+    category = fields.Many2One(
+        string='Category', required=True,
+        domain=[('accounting', '=', True)],
+        ondelete='CASCADE', model_name='product.category')
+
+# end ConfigProductcategoryRel