Hey Royce, This sounds like a job for composite columns: http://www.sqlalchemy.org/docs/orm/mapper_config.html#composite-column-types
One gotcha that I ran into here is that you cannot have both the component columns and the composite column mapped at the same time, like you do in your example. So depending on what you are trying to do, you might need to make a comparable property instead: http://www.sqlalchemy.org/docs/orm/mapper_config.html#custom-comparators Let me know if you need any more help. -Lenza On Mon, Jan 24, 2011 at 7:35 PM, Royce <roycek...@gmail.com> wrote: > Hi does anyone know if is possible to declaratively concatenate two > columns together which you can later do query's on. > > E.g. if I wanted to compute a new column course_name made up of > CONCAT(course_code,course_name) > > Base = declarative_base() > class Course(Base): > __tablename__ = 'Course' > > course_code = Column(VARCHAR(length=4), nullable=False) > course_num = Column(INTEGER(), nullable=False) > > course_name = func.CONCAT(course_code,course_num) # only an > example, this doesn't actually work > > > So later you could do queries on the Course table like > > course_data = > session.query(Course).filter( Course.course_name.op('regexp') > ('^A.*4') )).first() > print course_data.course_name > > > It is possible to do a query to generate the data outside the Course > class as below, but how can you > make it as a normal mapped column in the Course class ? > > query = session.query( func.CONCAT(Course.course_code, > Course.course_num) ) > query = query.filter( func.CONCAT(Course.course_code, > Course.course_num).op('regexp')('^A.*4') ) > > Cheers > Royce > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalchemy@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com<sqlalchemy%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
