[odb-users] odb::query problem

[luca paganotti]

Hi Boris,
thanks,
nice to know, what I was thinking about was that I could be able to
directly compare mykey objects as I declared them overriding the < operator
as the docs say operator < must be defined for composite values (and to
tell the truth I overrided also >= , <=, > == and != operators for class
mykey), I didn't imagine that I would split the comparing expression using
all the mykey members to this detail.

I wrote the query condition as

myquery::key >= kf && myquery::key <= kt

where kf and kt are myquery instances, instead of

myquery::key.t >= from   &&
myquery::key.t <= to     &&
myquery::key.s == strval &&
myquery::key.i == intval

but the latter is compiling and working.

Thank you.

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On Tue, May 4, 2021 at 3:25 PM Boris Kolpackov <boris at codesynthesis.com>
wrote:

> luca paganotti <luca.paganotti at gmail.com> writes:
>
> > mydb->erase_query<myclass>(myquery::key_ >= kf && myquery::key_ <= kt);
> >
> > anyway g++ complains this way on the last statement:
> >
> > error: ‘key_’ is not a member of ‘myquery’ {aka ‘odb::query<myclass>’}
>
> Right, but query::key is, as described in the documentation (ODB
> removes data member decorations like `m_` and trailing `_` for
> query members).
>
>
> > So it seems, key_ it's not a member of myquery that instead has a key
> > member, using that g++ gives tons of errors mainly saying that operands
> for
> > the overloaded operators are not of the same type
> > the first operand is of type
> >
> > const odb::query_columns<myclass, (odb::database_id)2,
> > odb::access::object_traits_impl<myclass, (odb::database_id)2>
> >::key_class_
> >
> > and the second one is of type mykey.
> >
> > As an additional info, I'm able to use the query functions that get a
> > std::string as parameter, but it will be nice to be able to use also the
> > others.
>
> Key is a composite value (it contains multiple members) so you need
> to pick the member you want to compare to, as in, query::key.member.
>