peeweeからOracleに接続しようとして挫折

oracledriver.py

#! /usr/bin/python2.7
# coding: utf-8

import peewee
import cx_Oracle
import os

class OracleDatabase(peewee.Database):
    def _connect(self, database, **kwargs):
        os.environ['NLS_LANG'] = 'JAPANESE_Japan.AL32UTF8'
        username = kwargs['username']
        password = kwargs['password']
        conn = cx_Oracle.connect(username, password, database)
        return conn

database = OracleDatabase(
    'XXX.XXX.XXX.XXX/SID',
    username='username',
    password='password',
)

class MyModel(peewee.Model):
    model_id = peewee.IntegerField(null=False)

    class Meta:
        database = database
        db_table = 'my_model'


def main():
    MyModel.create_table()
    m = MyModel.create(model_id=100)


if __name__ == '__main__':
    main()

"""
Traceback (most recent call last):
  File "oracledriver.py", line 45, in <module>
    main()
  File "oracledriver.py", line 39, in main
    m = MyModel.create(model_id=100)
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 4494, in create
    inst.save(force_insert=True)
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 4680, in save
    pk_from_cursor = self.insert(**field_dict).execute()
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 3213, in execute
    cursor = self._execute()
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 2628, in _execute
    return self.database.execute_sql(sql, params, self.require_commit)
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 3461, in execute_sql
    self.commit()
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 3285, in __exit__
    reraise(new_type, new_type(*exc_args), traceback)
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 3454, in execute_sql
    cursor.execute(sql, params or ())
peewee.DatabaseError: ORA-01036: 変数の名前/数が無効です。

Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/apport_python_hook.py", line 63, in apport_excepthook
    from apport.fileutils import likely_packaged, get_recent_crashes
  File "/usr/lib/python2.7/dist-packages/apport/__init__.py", line 5, in <module>
    from apport.report import Report
  File "/usr/lib/python2.7/dist-packages/apport/report.py", line 16, in <module>
    from xml.parsers.expat import ExpatError
  File "/usr/lib/python2.7/xml/parsers/expat.py", line 4, in <module>
    from pyexpat import *
ImportError: /usr/lib/python2.7/lib-dynload/pyexpat.x86_64-linux-gnu.so: undefined symbol: XML_SetHashSalt

Original exception was:
Traceback (most recent call last):
  File "oracledriver.py", line 45, in <module>
    main()
  File "oracledriver.py", line 39, in main
    m = MyModel.create(model_id=100)
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 4494, in create
    inst.save(force_insert=True)
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 4680, in save
    pk_from_cursor = self.insert(**field_dict).execute()
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 3213, in execute
    cursor = self._execute()
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 2628, in _execute
    return self.database.execute_sql(sql, params, self.require_commit)
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 3461, in execute_sql
    self.commit()
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 3285, in __exit__
    reraise(new_type, new_type(*exc_args), traceback)
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 3454, in execute_sql
    cursor.execute(sql, params or ())
peewee.DatabaseError: ORA-01036: 変数の名前/数が無効です。
"""

"""

生成されるSQL: INSERT INTO "my_model" (model_id) VALUES (?)
パラメータ: [100]

cx_Oracleではプレースホルダを :1 や :field_name で書く。 ? は使え無いのでエラーになる

"""