- the "scale" argument of the Numeric() type is honored when

coercing a returned floating point value into a string
on its way to Decimal - this allows accuracy to function
on SQLite, MySQL.  [ticket:1717]

3 files changed, 44 insertions, 11 deletions

diff --git a/lib/sqlalchemy/processors.py b/lib/sqlalchemy/processors.py
index 4cf6831bd..04fa5054a 100644
--- a/lib/sqlalchemy/processors.py
+++ b/lib/sqlalchemy/processors.py
@@ -38,9 +38,10 @@ try:
             return UnicodeResultProcessor(encoding, errors).process
         else:
             return UnicodeResultProcessor(encoding).process
-
-    def to_decimal_processor_factory(target_class):
-        return DecimalResultProcessor(target_class).process
+    
+    # TODO: add scale argument
+    #def to_decimal_processor_factory(target_class):
+    #    return DecimalResultProcessor(target_class).process
 
 except ImportError:
     def to_unicode_processor_factory(encoding, errors=None):
@@ -57,13 +58,14 @@ except ImportError:
                 return decoder(value, errors)[0]
         return process
 
-    def to_decimal_processor_factory(target_class):
-        def process(value):
-            if value is None:
-                return None
-            else:
-                return target_class(str(value))
-        return process
+    # TODO: add scale argument
+    #def to_decimal_processor_factory(target_class):
+    #    def process(value):
+    #        if value is None:
+    #            return None
+    #        else:
+    #            return target_class(str(value))
+    #    return process
 
     def to_float(value):
         if value is None:
@@ -92,3 +94,13 @@ except ImportError:
     str_to_time = str_to_datetime_processor_factory(TIME_RE, datetime.time)
     str_to_date = str_to_datetime_processor_factory(DATE_RE, datetime.date)
 
+
+def to_decimal_processor_factory(target_class, scale=10):
+    fstring = "%%.%df" % scale
+    
+    def process(value):
+        if value is None:
+            return None
+        else:
+            return target_class(fstring % value)
+    return process
diff --git a/lib/sqlalchemy/test/util.py b/lib/sqlalchemy/test/util.py
index 5be00f906..8a3a0e745 100644
--- a/lib/sqlalchemy/test/util.py
+++ b/lib/sqlalchemy/test/util.py
@@ -39,4 +39,15 @@ def picklers():
     for pickle in picklers:
         for protocol in -1, 0, 1, 2:
             yield pickle.loads, lambda d:pickle.dumps(d, protocol)
+    
+    
+def round_decimal(value, prec):
+    if isinstance(value, float):
+        return round(value, prec)
+    
+    import decimal
+
+    # can also use shift() here but that is 2.6 only
+    return (value * decimal.Decimal("1" + "0" * prec)).to_integral(decimal.ROUND_FLOOR) / \
+                        pow(10, prec)
     
\ No newline at end of file
diff --git a/lib/sqlalchemy/types.py b/lib/sqlalchemy/types.py
index d5f1d9f14..d7b8f9289 100644
--- a/lib/sqlalchemy/types.py
+++ b/lib/sqlalchemy/types.py
@@ -838,7 +838,7 @@ class Numeric(_DateAffinity, TypeEngine):
 #            try:
 #                from fastdec import mpd as Decimal
 #            except ImportError:
-            return processors.to_decimal_processor_factory(_python_Decimal)
+            return processors.to_decimal_processor_factory(_python_Decimal, self.scale)
         else:
             return None
 
@@ -877,6 +877,16 @@ class Float(Numeric):
     def adapt(self, impltype):
         return impltype(precision=self.precision, asdecimal=self.asdecimal)
 
+    def result_processor(self, dialect, coltype):
+        if self.asdecimal:
+            #XXX: use decimal from http://www.bytereef.org/libmpdec.html
+#            try:
+#                from fastdec import mpd as Decimal
+#            except ImportError:
+            return processors.to_decimal_processor_factory(_python_Decimal)
+        else:
+            return None
+
 
 class DateTime(_DateAffinity, TypeEngine):
     """A type for ``datetime.datetime()`` objects.