[Qt-interest] [ANN] ODB C++ ORM adds support for Qt

[Boris Kolpackov]

Hi Jason,

Jason H <scorp1us at yahoo.com> writes:

> One topic not covered (missing?) is multiple arbitrary table joins for
> queries. I do a ton of these a day. Is that something that is not there
> yet?

You can do it indirectly, via object relationships. For example:

class Employer
{
  ...

  QString name_;
};

class Employee
{
  ...

  QString name_;
  QLazySharedPointer<Employer> employer_;
};

Then you can do:

result r = db->query<Employee> (Query::name == "John Doe" &&
                                Query::employer::name == "Example, Inc");

In this query the Employer and Employee tables will be joined using
object ids in the ON condition.

It that something that would work for you?


> Also, it would be really cool (but not even NHibernate does this yet,
> IIRC) if these arbitrary queries could return a QObject derived class
> (creating the type at run-time via QMetaObject or minimally a QVariantMap.)

Well, that doesn't fall into the object-relational mapping per se. It
is just a convenient way to handle SQL result sets. While you can use
ODB like this (e.g., define plain struct's that just hold the data),
I am not sure about trying to actively support two very different
approaches to working with a database in the same tool.

Boris