[Sqlalchemy-tickets] Issue #3621: Oracle zxJDBC fails with AttributeError in object OracleCompiler_zxjdbc (zzzeek/sqlalchemy)

[Carlos R. <iss...@bi...>]

New issue 3621: Oracle zxJDBC fails with AttributeError in object OracleCompiler_zxjdbc
https://bitbucket.org/zzzeek/sqlalchemy/issues/3621/oracle-zxjdbc-fails-with-attributeerror-in

Carlos Rivas:

I understand that Oracle zxJDBC is not currently supported but, in my case, it seems that a simple fix has brought it back to life.

Currently, working with Oracle zxJDBC fails:

```
#!python
Traceback (most recent call last):
  File "/Users/carlos/projects/pydev/smaf-flask/main.py", line 70, in <module>
    db.session.commit()
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/scoping.py", line 150, in do
    return getattr(self.registry(), name)(*args, **kwargs)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/session.py", line 813, in commit
    self.transaction.commit()
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/session.py", line 392, in commit
    self._prepare_impl()
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/session.py", line 372, in _prepare_impl
    self.session.flush()
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/session.py", line 2027, in flush
    self._flush(objects)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/session.py", line 2145, in _flush
    transaction.rollback(_capture_exception=True)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/session.py", line 2109, in _flush
    flush_context.execute()
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/unitofwork.py", line 373, in execute
    rec.execute(self)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/unitofwork.py", line 529, in execute
    persistence.save_obj(self.mapper,
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/persistence.py", line 172, in save_obj
    _emit_insert_statements(base_mapper, uowtransaction,
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/orm/persistence.py", line 799, in _emit_insert_statements
    result = cached_connections[connection].\
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/engine/base.py", line 914, in execute
    return meth(self, multiparams, params)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/sql/elements.py", line 323, in _execute_on_connection
    return connection._execute_clauseelement(self, multiparams, params)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/engine/base.py", line 996, in _execute_clauseelement
    compiled_sql = elem.compile(
  File "<string>", line 1, in <lambda>
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/sql/elements.py", line 494, in compile
    return self._compiler(dialect, bind=bind, **kw)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/sql/elements.py", line 500, in _compiler
    return dialect.statement_compiler(dialect, self, **kw)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/dialects/oracle/base.py", line 581, in __init__
    super(OracleCompiler, self).__init__(*args, **kwargs)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/sql/compiler.py", line 392, in __init__
    Compiled.__init__(self, dialect, statement, **kwargs)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/sql/compiler.py", line 190, in __init__
    self.string = self.process(self.statement, **compile_kwargs)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/sql/compiler.py", line 213, in process
    return obj._compiler_dispatch(self, **kwargs)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/sql/visitors.py", line 81, in _compiler_dispatch
    return meth(self, **kw)
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/sql/compiler.py", line 1875, in visit_insert
    returning_clause = self.returning_clause(
  File "/opt/python/jyflask/Lib/site-packages/sqlalchemy/dialects/oracle/zxjdbc.py", line 74, in returning_clause
    columns = [self.process(c, within_columns_clause=False,
AttributeError: 'OracleCompiler_zxjdbc' object has no attribute 'result_map'
```
It seems that the problem stems from within the `zxjdbc.py` file in `oracle/dialects` folder.  

Changing line:
```
#!python
        # within_columns_clause=False so that labels (foo AS bar) don't render
        columns = [self.process(c, within_columns_clause=False,
                                result_map=self.result_map)
                   for c in self.returning_cols]
```

to:

```
#!python
        # within_columns_clause=False so that labels (foo AS bar) don't render
        columns = [self.process(c, within_columns_clause=False,
                                result_map=self._create_result_map())
                   for c in self.returning_cols]
```

seems to fix the issue.  I've searched BitBucket for an existing ticket but to no avail.  Please, can you let me know that this is the correct approach to fix this file?  Thanks!

Responsible: zzzeek