Re: [SQLObject] _fromDatabase + configurable database connections

[Kevin D. <da...@gm...>]

On 7/20/05, Jennings Jared L Contr 46 SK/CCI
<jar...@eg...> wrote:
> kevin dangoor said:=20
> > jared jennings said:=20
> > >     class User(SQLObject):=20
> > >         _fromDatabase =3D True=20
> > >     #...=20
> > >     User._connection =3D myConnection=20
> > >     User.addColumnsFromDatabase()=20
> > >     u =3D User.get(17)=20
> > >     print u.shortName=20
> >=20
> > Does this work as written? Or do you get an error by=20
> > specifying _fromDatabase=3DTrue without providing a connection?=20
>=20
> No, there's an error. The __classinit__ calls addColumnsFromDatabase, whi=
ch
> fails without the _connection.=20

I guess it would be possible to add a flag that effectively says "I'll
add the columns later" to help with this specific scenario.

> I have an SQL script that sets up the database, so I didn't want to put t=
he
> field definitions in Python too. I couldn't create the tables using only
> SQLObject, because (1) there are many people here for whom SQL is normal =
and
> Python is new, (2) there are permissions and views to set up.=20

Don't Repeat Yourself is a good motto.

Actually, in the project I'm working on I have had to do some
database-specific calls in the creation process (which is written in
Python). What I did was access the low-level connection object (ie not
SQLObject's connection object, but the one SQLObject is holding on to)
to do the low-level stuff, and then I'd loop through the modules'
__dicts__ to find SQLObject classes and create those tables in the
database using SQLObject.

> I could give up and put the column definitions in the class; this seems t=
o
> be more idiomatic to SQLObject, at least in my type of application.=20

Depending on how frequently you change your schema, that could be a
real drag. Personally, I would either do the database initialization
in a Python script (as above) or think about making
addColumnsFromDatabase work as you have pictured above.

Kevin