switching Decimal treatment in MSSQL to be pyodbc specific, added

to connector to share between sybase/mssql.   Going
with turning decimals with very low significant digit to floats,
seems to work so far.

1 files changed, 53 insertions, 0 deletions

diff --git a/lib/sqlalchemy/connectors/pyodbc.py b/lib/sqlalchemy/connectors/pyodbc.py
index e503135f7..5cfe4a192 100644
--- a/lib/sqlalchemy/connectors/pyodbc.py
+++ b/lib/sqlalchemy/connectors/pyodbc.py
@@ -4,6 +4,59 @@ from sqlalchemy.util import asbool
 import sys
 import re
 import urllib
+import decimal
+from sqlalchemy import processors, types as sqltypes
+
+class PyODBCNumeric(sqltypes.Numeric):
+    """Turns Decimals with adjusted() < -6 into floats."""
+    
+    def bind_processor(self, dialect):
+        super_process = super(PyODBCNumeric, self).bind_processor(dialect)
+        
+        def process(value):
+            if self.asdecimal and \
+                    isinstance(value, decimal.Decimal) and \
+                    value.adjusted() < -6:
+                return processors.to_float(value)
+            elif super_process:
+                return super_process(value)
+            else:
+                return value
+        return process
+
+    # This method turns the adjusted into a string.
+    # not sure if this has advantages over the simple float
+    # approach above.
+#    def bind_processor(self, dialect):
+#        def process(value):
+#            if isinstance(value, decimal.Decimal):
+#                if value.adjusted() < 0:
+#                    result = "%s0.%s%s" % (
+#                            (value < 0 and '-' or ''),
+#                            '0' * (abs(value.adjusted()) - 1),
+#                            "".join([str(nint) for nint in value._int]))
+#
+#                else:
+#                    if 'E' in str(value):
+#                        result = "%s%s%s" % (
+#                                (value < 0 and '-' or ''),
+#                                "".join([str(s) for s in value._int]),
+#                                "0" * (value.adjusted() - (len(value._int)-1)))
+#                    else:
+#                        if (len(value._int) - 1) > value.adjusted():
+#                            result = "%s%s.%s" % (
+#                                    (value < 0 and '-' or ''),
+#                                    "".join([str(s) for s in value._int][0:value.adjusted() + 1]),
+#                                    "".join([str(s) for s in value._int][value.adjusted() + 1:]))
+#                        else:
+#                            result = "%s%s" % (
+#                                    (value < 0 and '-' or ''),
+#                                    "".join([str(s) for s in value._int][0:value.adjusted() + 1]))
+#                return result
+#
+#            else:
+#                return value
+#        return process
 
 class PyODBCConnector(Connector):
     driver='pyodbc'