Fwd: [odb-users] Error when trying to use odb compiler on custom class

[Rafal Grasman]

Yep this totally works (struct), I just commented out the tuple as for now,
thank you very much! Amazing software :) I really hate making SQL queries ;f


2013/5/15 Boris Kolpackov <boris at codesynthesis.com>

> Hi Rafal,
>
> Rafal Grasman <rjg1094 at gmail.com> writes:
>
> > Ah, it works for the ODB compiler but now Visual Studio is complaining on
> > the generated header
>
> I tried your example, and, actually, mapping std::tuple is tricky
> because it doesn't contain the members directly (like, for example,
> std::pair). Rather, it uses base classes to "allocate" the required
> number of elements.
>
> So, if you don't have a requirement to use tuples, then it will
> probably be much easier and more straightforward to reimplement
> this as a struct/class. For example:
>
> #pragma db value
> struct ban_type
> {
>   std::string first;
>   unsigned long long second;
>   std::string third;
>   unsigned long long fourth;
> };
>
> You will probably want to use more descriptive names instead of first,
> second, etc.
>
> Now, if you must use std::tuple, then it should be possible to map it
> using the virtual data member feature in ODB. For example:
>
> typedef std::tuple<std::string,
>                    unsigned long long,
>                    std::string,
>                    unsigned long long> ban_type;
>
> #pragma db value(ban_type) transient
> #pragma db member(ban_type::first) virtual(std::string) access(std::get<0>
> (this))
> #pragma db member(ban_type::second) virtual(unsigned long long)
> access(std::get<1> (this))
> #pragma db member(ban_type::third) virtual(std::string) access(std::get<2>
> (this))
> #pragma db member(ban_type::fourth) virtual(unsigned long long)
> access(std::get<3> (this))
>
> As you can see it is quite verbose.
>
> Above I said "should" instead of "can" because the current version of
> ODB (2.2.0) has a bug that prevents this mapping from working. I've
> fixed it for the next release of ODB so once 2.3.0 is out, it will
> work.
>
> Boris
>