how can I define the type result of "make_storage" function as a member variable of c++ class.

[CodingPanda87]

auto storage = make_storage("db.sqlite",
make_table("users",
make_column("id", &User::id, autoincrement(), primary_key()),
make_column("first_name", &User::firstName),
make_column("last_name", &User::lastName),
make_column("birth_date", &User::birthDate),
make_column("image_url", &User::imageUrl),
make_column("type_id", &User::typeId)),
make_table("user_types",
make_column("id", &UserType::id, autoincrement(), primary_key()),
make_column("name", &UserType::name, default_value("name_placeholder"))));

for example:

class myBusiness
{
public:
bool initial(std::string filePath){
m_storage = make_storage(filePath,
make_table("users",
make_column("id", &User::id, autoincrement(), primary_key()),
make_column("first_name", &User::firstName),
make_column("last_name", &User::lastName),
make_column("birth_date", &User::birthDate),
make_column("image_url", &User::imageUrl),
make_column("type_id", &User::typeId)),
make_table("user_types",
make_column("id", &UserType::id, autoincrement(), primary_key()),
make_column("name", &UserType::name, default_value("name_placeholder"))));
return m_storage.is_open();
}
private:
xxxxx_type m_storage;
}

what is "xxxxx_type"?

thank you very much !!!

[fnc12]

https://github.com/fnc12/sqlite_orm/wiki/FAQ

[CodingPanda87]

thank you!

[DominicD]

@fnc12
I also have a problem with this. I tried this:

    #include "sqlite_orm/sqlite_orm.h"
    
    struct User
    {
        int id;
    };
    
    inline auto initStorage(const std::string& path) {
        using namespace sqlite_orm;
        return
	        make_storage(path,
		        make_table("users",
			        make_column("id", &User::id, autoincrement(), primary_key())
		        )
	        );
    }
    using Storage = decltype(initStorage(""));
    
    class Example
    {
    public:
        bool initial(std::string filePath) {
	        m_storage = initStorage(filePath);
        }
    private:
    
        Storage m_storage;
    };

This gives me following error for "m_storage = initStorage(filePath);"

error C2280: 'sqlite_orm::internal::storage_t<sqlite_orm::internal::table_t<User,sqlite_orm::internal::column_t<User,int,const int &(__cdecl User::* )(void) const,void (__cdecl User::* )(int),sqlite_orm::constraints::autoincrement_t,sqlite_orm::constraints::primary_key_t<>>>> &sqlite_orm::internal::storage_t<sqlite_orm::internal::table_t<User,sqlite_orm::internal::column_t<User,int,const int &(__cdecl User::* )(void) const,void (__cdecl User::* )(int),sqlite_orm::constraints::autoincrement_t,sqlite_orm::constraints::primary_key_t<>>>>::operator =(const sqlite_orm::internal::storage_t<sqlite_orm::internal::table_t<User,sqlite_orm::internal::column_t<User,int,const int &(__cdecl User::* )(void) const,void (__cdecl User::* )(int),sqlite_orm::constraints::autoincrement_t,sqlite_orm::constraints::primary_key_t<>>>> &)': attempting to reference a deleted function

But even if it worked. I actually want something else.
I don´t want to expose sqlite_orm outside of this class so I do not want to have the include in the header. Same goes for everything that is used in initStorage (in this case the User struct). However seems like a inline function can not be defined in the cpp if it is declared in the header.

Only thing I came up with is this:

    // example.h :
    #include <any>
    #include <string>
    
    class Example
    {
    public:
        void initial(std::string filePath);
    private:
    
        std::any m_storage;
    };
    
    //example.cpp :
    //#include "example.h"
    #include "sqlite_orm/sqlite_orm.h"
    
    struct User
    {
        int id;
    };
    
    inline auto initStorage(const std::string& path) {
        using namespace sqlite_orm;
        return
	        make_storage(path,
		        make_table("users",
			        make_column("id", &User::id, autoincrement(), primary_key())
		        )
	        );
    }
    using Storage = decltype(initStorage(""));
    
    void Example::initial(std::string filePath) {
        m_storage = initStorage(filePath);
    
        // to use it I have to make ugly cast:
        auto user = std::any_cast<Storage&>(m_storage).get<User>();
    }

Would be great if you have a better solution. Maybe I am missing something obvious?

[fnc12]

you cannot assign a storage to a storage. You need to init a storage (to call a constructor). You you have a later init then store your storage as a nullable value:
instead of Storage m_storage; store std::unique_ptr<Storage> m_storage;

[DominicD]

Ah yes this solves the first example.
But what about the second one? Which I actually want to use.
Any advice how it could be improved?

[fnc12]

@DominicD which example are you talking about? How to eliminate includes of your data files inside header? If so then it is unable cause storage uses all these types inside its type declaration just like std::tuple uses all types included as template argument. You can try to use forward declaration but it requires using of sqlite_orm private API. The example also exists inside FAQ https://github.com/fnc12/sqlite_orm/wiki/FAQ#slow--size-effective

[DominicD]

Ok thank you for clarification