Using boost::tuple with ORM

[VadVergasov]

I'm trying to use tuple with my type and some other. Here is the example of the code:

std::string query = "SELECT stock.*, laptop.name, provider.name FROM stock JOIN laptop ON laptop.id=stock.laptop JOIN provider ON provider.id=stock.source LIMIT 10";
soci::rowset<boost::tuple<stock, std::string, std::string>> rs = (sql.prepare << query);
for (auto it = rs.begin(); it != rs.end(); it++) {
    result.push_back({it->get<0>(), it->get<1>()});
}

And I'm getting such exception: Cannot convert data while fetching data from "SELECT stock.*, laptop.name, provider.name FROM stock JOIN laptop ON laptop.id=stock.laptop JOIN provider ON provider.id=stock.source LIMIT 10". In struct stock there are all required conversions (Here is the code). Is SOCI isn't supporting using tuples with ORM types, only based on base types?

[zann1x]

I'm not familiar with the boost integration of SOCI, but my guess is that you're either missing the soci/boost-tuple.h include or SOCI doesn't provide a type_conversion for boost::tuple anymore, so you have to provide your own for that (see below).

https://github.com/SOCI/soci/blob/98e0b8b7866ff6f9f0184ddea08d0c3b723cb77b/src/core/boost-tuple.h#L63-L85

[VadVergasov]

I've included boost-tuple.h and it works with base types like string, int and etc. but not with ORM types.

[VadVergasov]

Also I'm getting exception:

Only one Row element allowed in a single statement.

when trying to execute this code:

std::string query = "SELECT stock.*, laptop.*, provider.* FROM stock JOIN laptop ON laptop.id = stock.laptop JOIN provider ON provider.id = stock.source LIMIT 10";
soci::rowset<boost::tuple<stock, laptop, provider>> rs = (sql.prepare << query);

Also all types are defined and added all required conversions. Can't find any additional info about this exception