AW: [odb-users] One-to-many bidirectional relationship without intermediary table

[Mocnik Marko]

Okay, the generated SQL does look pretty good with the 'points_to' directive. (Took me some time to realize that this requires odb 2.5)
And I got the virtual data member mapping in testi2 to work like you sketched.

But how do I get now a bidirectional mapping?
Especially a vector of Testi2 s in Testi?
Also with a virtual data member? The docs did not help me on how to do that with a vector.


> I was able to get the identical mapping using these classes:
>
> #pragma db object
> struct testi
> {
>   #pragma db id
>   int asdf;
> };
>
> #pragma db object
> struct testi2
> {
>   #pragma db value
>   struct id_type
>   {
>     #pragma db points_to(testi)
>     int asdf;
>     int qwer;
>   };
>
>   #pragma db id column("")
>   id_type id;
> };
>
> The generated database schema (PostgreSQL version):
>
> CREATE TABLE "testi" (
>   "asdf" INTEGER NOT NULL PRIMARY KEY);
>
> CREATE TABLE "testi2" (
>   "asdf" INTEGER NOT NULL,
>   "qwer" INTEGER NOT NULL,
>   PRIMARY KEY ("asdf",
>                "qwer"),
>   CONSTRAINT "asdf_fk"
>     FOREIGN KEY ("asdf")
>     REFERENCES "testi" ("asdf")
>     INITIALLY DEFERRED);
>
> With virtual data members and a bit of effort you should be able to change testi2::id_type::asdf to a pointer, something along these lines (a sketch):
>
> #pragma db object
> struct testi2
> {
>   #pragma db transient
>   testi* asdf;
>
>   #pragma db transient
>   int qwer;
>
>   #pragma db value
>   struct id_type
>   {
>     #pragma db points_to(testi)
>     int asdf;
>     int qwer;
>   };
>
>   #pragma db member(id) virtual(id_type) id column("") \
>     get (...) \
>     set (...)
> };