[odb-users] Query on non-empty container in view

[Boris Kolpackov]

Hi Lukas,

Lukas Obermann <obermann.lukas at gmail.com> writes:

> So, having a class that has some containers
> (std::vector<odb::lazy_shared_ptr>) in a class and a view on top of that to
> access the elements.
> 
> What is the recommended way of querying that the vector must have at least
> one element in it?

If pointers in your vector cannot be NULL (which would generally be
pointless in this case, no pun intended), then you can just join
the pointed-to object and add a test like "its object id is not NULL"
(or use an appropriate join type).

Boris