[odb-users] How to cache the queried object pointer?

Justin Huang yohuang at nvidia.com
Wed Oct 30 22:40:29 EDT 2019


I'd like to load sqlite3 DB back, construct C++ objects, and save the object pointers for later usage.

I have 3 Module entries in the Module table, the code below is used. It is weird that the 'ptr' of the 1st Module is destructed before looping the 2nd Module, but 2nd/3rd Module ptr are not destructed.

I wonder how should we cache the queried object pointers for later use? I don't want to create new Module using copy constructor from the result::iterator, because the Modules can have cross references (I mean point to each other) in class definition and creating new Module objects would require updating all the cross references.


class DB {
     void load_db(int argc, char* argv[]);
std::vector<Module *> modules;

void DB::load_db(int argc, char* argv[])
session s;
db = std::unique_ptr<odb::database>(create_database (argc, argv));

     // load all modules in Module table back into C++ objects
          odb::transaction t (db->begin());

           typedef odb::result<Module> result;
           result all_modules (db->query<Module> ());

           int count = 0;
           for (result::iterator i(all_modules.begin()); i != all_modules.end(); ++i) {
                auto ptr = i.operator->();

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