SUBSTR doesn't allow negative length

issue3150
review793002

trytond/ir/translation.py

@@ -144,7 +144,10 @@ class Translation(ModelSQL, ModelView):
     def search_model(cls, name, clause):
         cursor = Transaction().cursor
         cursor.execute('SELECT id FROM "%s" '
-            'WHERE SUBSTR(name, 1, POSITION(\',\' IN name) - 1) %s %%s' %
+            'WHERE SUBSTR(name, 1, '
+            'CASE WHEN POSITION(\',\' IN name) > 0 '
+                'THEN POSITION(\',\' IN name) - 1 '
+                'ELSE 0 END) %s %%s' %
             (cls._table, clause[1]), (clause[2],))
         return [('id', 'in', [x[0] for x in cursor.fetchall()])]