[FIX] fields: do not serialize more digits than necessary in monetary._symbol_set()

Add a class for float objects that carry their precision digits, use it for the
value of monetary fields in record cache, and serialize them as expected for
the database.

openerp/addons/test_new_api/models.py

@@ -264,6 +264,9 @@ class MixedModel(models.Model):
     comment3 = fields.Html(sanitize=True, strip_classes=True)
     comment4 = fields.Html(sanitize=True, strip_style=True)
 
+    currency_id = fields.Many2one('res.currency', default=lambda self: self.env.ref('base.EUR'))
+    amount = fields.Monetary()
+
     @api.one
     def _compute_now(self):
         # this is a non-stored computed field without dependencies

openerp/addons/test_new_api/tests/test_new_fields.py

@@ -235,6 +235,22 @@ class TestNewFields(common.TransactionCase):
         record.number = 2.4999999999999996
         self.assertEqual(record.number, 2.50)
 
+    def test_20_monetary(self):
+        """ test monetary fields """
+        record = self.env['test_new_api.mixed'].create({})
+        self.assertTrue(record.currency_id)
+        self.assertEqual(record.currency_id.rounding, 0.01)
+
+        # the conversion to cache should round the value to 14.700000000000001
+        record.amount = 14.7
+        self.assertNotEqual(record.amount, 14.7)
+        self.assertEqual(record.amount, 14.700000000000001)
+
+        # however when stored to database, it should be serialized as 14.70
+        self.cr.execute('SELECT amount FROM test_new_api_mixed WHERE id=%s', (record.id,))
+        (amount,) = self.cr.fetchone()
+        self.assertEqual(amount, 14.7)
+
     def test_21_date(self):
         """ test date fields """
         record = self.env['test_new_api.mixed'].create({})

openerp/fields.py

@@ -13,7 +13,7 @@ import pytz
 import xmlrpclib
 
 from openerp.sql_db import LazyCursor
-from openerp.tools import float_round, frozendict, html_sanitize, ustr, OrderedSet
+from openerp.tools import float_precision, float_round, frozendict, html_sanitize, ustr, OrderedSet
 from openerp.tools import DEFAULT_SERVER_DATE_FORMAT as DATE_FORMAT
 from openerp.tools import DEFAULT_SERVER_DATETIME_FORMAT as DATETIME_FORMAT
 from openerp.tools.translate import html_translate
@@ -1177,7 +1177,8 @@ class Monetary(Field):
             # FIXME @rco-odoo: currency may not be already initialized if it is
             # a function or related field!
             if currency:
-                return currency.round(float(value or 0.0))
+                value = currency.round(float(value or 0.0))
+                return float_precision(value, currency.decimal_places)
         return float(value or 0.0)
 
 

openerp/osv/fields.py

@@ -404,9 +404,15 @@ class float(_column):
     def digits_change(self, cr):
         pass
 
+def _symbol_set_monetary(val):
+    try:
+        return val.float_repr()         # see float_precision.float_repr()
+    except Exception:
+        return __builtin__.float(val or 0.0)
+
 class monetary(_column):
     _type = 'monetary'
-    _symbol_set = ('%s', lambda x: __builtin__.float(x or 0.0))
+    _symbol_set = ('%s', _symbol_set_monetary)
     _symbol_get = lambda self,x: x or 0.0
 
     def to_field_args(self):

openerp/tools/float_utils.py

@@ -148,6 +148,25 @@ def float_repr(value, precision_digits):
     # precision. e.g. str(123456789.1234) == str(123456789.123)!!
     return ("%%.%sf" % precision_digits) % value
 
+_float_repr = float_repr
+
+class float_precision(float):
+    """ A class for float values that carry precision digits. This is a thin
+        layer on top of ``float``, and the precision digits are not propagated
+        to the result of arithmetic operations. This class is used when
+        converting monetary values to cache, and for serializing them to the
+        database.
+    """
+    __slots__ = ['precision_digits']
+
+    def __new__(cls, value, precision_digits):
+        obj = super(float_precision, cls).__new__(cls, value)
+        obj.precision_digits = precision_digits
+        return obj
+
+    def float_repr(self):
+        return _float_repr(self, self.precision_digits)
+
 
 if __name__ == "__main__":