morro

sqlalchemy/dialects/sybase/pyodbc.py

@@ -0,0 +1,75 @@
+"""
+Support for Sybase via pyodbc.
+
+http://pypi.python.org/pypi/pyodbc/
+
+Connect strings are of the form::
+
+    sybase+pyodbc://<username>:<password>@<dsn>/
+    sybase+pyodbc://<username>:<password>@<host>/<database>
+
+Unicode Support
+---------------
+
+The pyodbc driver currently supports usage of these Sybase types with 
+Unicode or multibyte strings::
+
+    CHAR
+    NCHAR
+    NVARCHAR
+    TEXT
+    VARCHAR
+
+Currently *not* supported are::
+
+    UNICHAR
+    UNITEXT
+    UNIVARCHAR
+    
+"""
+
+from sqlalchemy.dialects.sybase.base import SybaseDialect, SybaseExecutionContext
+from sqlalchemy.connectors.pyodbc import PyODBCConnector
+import decimal
+from sqlalchemy import types as sqltypes, util, processors
+
+class _SybNumeric_pyodbc(sqltypes.Numeric):
+    """Turns Decimals with adjusted() < -6 into floats.
+    
+    It's not yet known how to get decimals with many 
+    significant digits or very large adjusted() into Sybase
+    via pyodbc.
+    
+    """
+
+    def bind_processor(self, dialect):
+        super_process = super(_SybNumeric_pyodbc, self).bind_processor(dialect)
+
+        def process(value):
+            if self.asdecimal and \
+                    isinstance(value, decimal.Decimal):
+
+                if value.adjusted() < -6:
+                    return processors.to_float(value)
+
+            if super_process:
+                return super_process(value)
+            else:
+                return value
+        return process
+
+class SybaseExecutionContext_pyodbc(SybaseExecutionContext):
+    def set_ddl_autocommit(self, connection, value):
+        if value:
+            connection.autocommit = True
+        else:
+            connection.autocommit = False
+
+class SybaseDialect_pyodbc(PyODBCConnector, SybaseDialect):
+    execution_ctx_cls = SybaseExecutionContext_pyodbc
+
+    colspecs = {
+        sqltypes.Numeric:_SybNumeric_pyodbc,
+    }
+
+dialect = SybaseDialect_pyodbc