SQLAlchemy dialect for renamed columns

sqlabaan.py

import copy

import sqlalchemy.engine.base
import sqlalchemy.dialects.mssql.base
import sqlalchemy.dialects.mssql.pyodbc

class SQLABaanRowProxy(sqlalchemy.engine.base.RowProxy):
    def __init__(self, parent, row, processors, keymap):
        """
            For all keys starting with "t_" adds also a "t$..." key.
        """
        km = copy.deepcopy(keymap)
        for (k, v) in keymap.iteritems():
            if isinstance(k, basestring):
                if k.startswith("t_"):
                    km["t$" + k[2:]] = v
        super(SQLABaanRowProxy, self).__init__(parent, row, processors, km)

class SQLABaanResultProxy(sqlalchemy.engine.base.ResultProxy):
    _process_row = SQLABaanRowProxy

class SQLABaanCompiler(sqlalchemy.dialects.mssql.base.MSSQLCompiler):
    def visit_select(self, select, **kwargs):
        """
            Brute-force replace of "t$" to "t_...":w
        """
        ret = super(SQLABaanCompiler, self).visit_select(select, **kwargs)
        ret = ret.replace("t$", "t_")
        return ret

class SQLABaanExecutionContext(sqlalchemy.dialects.mssql.pyodbc.MSExecutionContext_pyodbc):
    def get_result_proxy(self):
        if self._result_proxy:
            return self._result_proxy   #can never happen as we do only selects
        else:
            return SQLABaanResultProxy(self)


class SQLABaan(sqlalchemy.dialects.mssql.pyodbc.MSDialect_pyodbc):
    execution_ctx_cls = SQLABaanExecutionContext
    statement_compiler = SQLABaanCompiler

dialect = SQLABaan