associate python types with SQL types

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2006/2/24, Michael Bayer : so, you want a mapping of types.TypeEngine types to python type objects ? I suppose we could add a "python_type" accessor on each TypeEngine (i.e. types.String.python_type == str). would that work ?

Yes that would be perfect. I think the mapping will have to be hard coded since there is no way to get it from the dbapi... Do you think it could also be useful using type checking in the setattr of a mapped class? for instance:

mapped.attribute = 'foo'

if attribute refers to a types.Integer it would fail with a TypeError.

On Feb 24, 2006, at 8:15 AM, Michele Comitini wrote:

Hello Michael,

Thanks for your great piece of software.

I have a question about getting type information from a mapper created with reflection. How do I know the python type of a mapped attribute without having to extract at least one record?

Right now I do this:

colnames = mapper.c.keys()
coltypes = [type(getattr(mapper.select()[0](type(getattr(mapper.select()[0),x)) for x in colnames]

which would fail if I have an empty table This way I know which python types I can expect as a result of a select() on that mapper and what types I have to use on insert. While if do:

If I do this:

colnames = mapper.c.keys()
coltypes = [for x in colnames]((getattr(mapper,x)).type)

I get the sqlalchemy.types (or derivatives) which tell me only the type stored in the db.

This could be useful to check for correct type binding before actually having the driver raising an exception and manage type conversion on the python side.

Thanks for you help and keep up the great work!

Michele Comitini

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