Questions on projection/DTO nesting

[cambierr]

Hi,

Based on https://docs.spring.io/spring-data/r2dbc/docs/current/reference/html/#projections I understand that nesting is supposed to work, which I'm about to investigate but I'm wondering how this is actually working and what's allowed.

First, given a tables A(col_a1, col_a2) and B(col_b1, col_b2, col_a1), the last column of B being a foreign key to A.col_a1. The documentation seems to say that something like

class A{
    String colA1;
    String colA2;
    B b;

    static class B{
        String colB1;
        String colB2;
    }
};

interface ARepository extends Repository<A, String> {
    Flux<A> findBycolA1(String colA1);
}

How is this supposed to be mapped to a + a.b ?

I guess we should build something like

interface ARepository extends Repository<A, String> {
    @Query("SELECT * FROM A WHERE col_a1 = :colA1 join B on a.colA1 = b.colA1")
    Flux<A> findBycolA1(String colA1);
}

and I can understand that the mapping would work using this model. Would it be right ?

A final question would then be; if 1-to-1 mapping works, should 1-to-n mapping work too ? If so, under which conditions ?

Thank you already, guys.

[mp911de]

Relational nesting isn't supported yet by Spring Data R2DBC.

[mp911de]

Duplicates #356 and #288