Fix synonym for dtransactions.tax

corepos/db/office_trans/model.py

@@ -26,6 +26,7 @@ CORE POS Transaction Data Model
 
 import sqlalchemy as sa
 from sqlalchemy import orm
+from sqlalchemy.ext.declarative import declared_attr
 
 
 Base = orm.declarative_base()
@@ -121,7 +122,10 @@ class TransactionDetailBase(object):
     reg_price = sa.Column('regPrice', sa.Numeric(precision=10, scale=2), nullable=True)
 
     tax = sa.Column(sa.SmallInteger(), nullable=True)
-    tax_rate_id = orm.synonym('tax')
+
+    @declared_attr
+    def tax_rate_id(self):
+        return orm.synonym('tax')
 
     food_stamp = sa.Column('foodstamp', sa.Boolean(), nullable=True)