I'm working with an existing MySQL schema that has lots of columns of
type ENUM('N', 'Y'). I'd like to deal with them as real booleans on
the python side.
I have a simple TypeDecorator which almost works (I think):
class YNBoolean(sqlalchemy.types.TypeDecorator):
impl = mysql.ENUM('N', 'Y', charset='ascii')
def process_bind_param(self, value, dialect):
if value is None:
return value
return 'Y' if value else 'N'
def process_result_value(self, value, dialect):
if value is None:
return None
return value == 'Y'
The one problem I've discovered with this is that
session.query(MyTable).filter(MyTable.ynbool)
produces a query like
SELECT ... FROM MyTable WHERE MyTable.ynbool;
What I really want is
SELECT ... FROM MyTable WHERE MyTable.ynbool = 'Y';
(If I do .filter(MyTable.ynbool == True) that does work as desired/expected.)
Is there a way to customize how my column gets compiled when used
in an expression in a boolean context? (If not, I can live with it
as is. I'll just get surprised once in awhile when I forget that
treating the column as a boolean in expressions won't work.)
Thank you for any help.
Jeff
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