- support for cdecimal

- add --with-cdecimal flag to tests, monkeypatches cdecimal in
- fix mssql/pyodbc.py to not use private '_int' accessor in decimal conversion
routines
- pyodbc version 2.1.8 is needed for cdecimal in any case as
previous versions also called '_int', 2.1.8 adds the same string
logic as our own dialect, so that logic is skipped for modern
pyodbc version
- make the imports for "Decimal" consistent across the whole lib.  not sure
yet how we should be importing "Decimal" or what the best way forward
is that would allow a clean user-invoked swap of cdecimal; for now,
added docs suggesting a global monkeypatch - the two decimal libs
are not compatible with each other so any chance of mixing produces
serious issues.  adding adapters to DBAPIs tedious and adds in-python
overhead.  suggestions welcome on how we should be doing
Decimal/cdecimal.

1 files changed, 19 insertions, 8 deletions

diff --git a/lib/sqlalchemy/dialects/mssql/pyodbc.py b/lib/sqlalchemy/dialects/mssql/pyodbc.py
index 5bba24514..93a516706 100644
--- a/lib/sqlalchemy/dialects/mssql/pyodbc.py
+++ b/lib/sqlalchemy/dialects/mssql/pyodbc.py
@@ -88,7 +88,12 @@ class _MSNumeric_pyodbc(sqltypes.Numeric):
     """
 
     def bind_processor(self, dialect):
-        super_process = super(_MSNumeric_pyodbc, self).bind_processor(dialect)
+        
+        super_process = super(_MSNumeric_pyodbc, self).\
+                        bind_processor(dialect)
+
+        if not dialect._need_decimal_fix:
+            return super_process
 
         def process(value):
             if self.asdecimal and \
@@ -106,31 +111,35 @@ class _MSNumeric_pyodbc(sqltypes.Numeric):
                 return value
         return process
     
+    # these routines needed for older versions of pyodbc.
+    # as of 2.1.8 this logic is integrated.
+    
     def _small_dec_to_string(self, value):
         return "%s0.%s%s" % (
                     (value < 0 and '-' or ''),
                     '0' * (abs(value.adjusted()) - 1),
-                    "".join([str(nint) for nint in value._int]))
+                    "".join([str(nint) for nint in value.as_tuple()[1]]))
 
     def _large_dec_to_string(self, value):
+        _int = value.as_tuple()[1]
         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)))
+                    "".join([str(s) for s in _int]),
+                    "0" * (value.adjusted() - (len(_int)-1)))
         else:
-            if (len(value._int) - 1) > value.adjusted():
+            if (len(_int) - 1) > value.adjusted():
                 result = "%s%s.%s" % (
                 (value < 0 and '-' or ''),
                 "".join(
-                    [str(s) for s in value._int][0:value.adjusted() + 1]),
+                    [str(s) for s in _int][0:value.adjusted() + 1]),
                 "".join(
-                    [str(s) for s in value._int][value.adjusted() + 1:]))
+                    [str(s) for s in _int][value.adjusted() + 1:]))
             else:
                 result = "%s%s" % (
                 (value < 0 and '-' or ''),
                 "".join(
-                    [str(s) for s in value._int][0:value.adjusted() + 1]))
+                    [str(s) for s in _int][0:value.adjusted() + 1]))
         return result
     
     
@@ -200,5 +209,7 @@ class MSDialect_pyodbc(PyODBCConnector, MSDialect):
         self.description_encoding = description_encoding
         self.use_scope_identity = self.dbapi and \
                         hasattr(self.dbapi.Cursor, 'nextset')
+        self._need_decimal_fix = self.dbapi and \
+                                tuple(self.dbapi.version.split(".")) < (2, 1, 8)
         
 dialect = MSDialect_pyodbc