I'm working with a IBM DB2 database using ibm_db2 driver and sqlalchemy. My model is:

class User(Model):id          = Column('UID', Integer, primary_key=True)user        = Column('USER', String(20))password    = Column('PASSWORD', String(10))name        = Column('NAME', String(30))

String fields from the database (e.g. name) comes in the form of:

>>> "John                                "

, where the value is filled right with blanks to the full length of the field by schema.

I need to change this behavior to the sqlalchemy type String (or a derivative thereof) produced follow (e.g. value.strip()) before output results by query.all():

>>> "John"

How can I do this?

@property decorator is not applicable. I need to change the behavior of a standard sqlalchemy String class.

I would not want to change the behaviour of the standard String but to make a new type (you can then rename it to String per module basis or whatever) but it is cleanest that way:

from sqlalchemy import typesclass StrippedString(types.TypeDecorator):"""Returns CHAR values with spaces stripped"""impl = types.Stringdef process_bind_param(self, value, dialect):"No-op"return valuedef process_result_value(self, value, dialect):"""Strip the trailing spaces on resulting values.If value is false, we return it as-is; it might be nonefor nullable columns"""return value.rstrip() if value else valuedef copy(self):"Make a copy of this type"return StrippedString(self.impl.length)

Now you can use StrippedString instead of String