How do you use define nested structs?

[aidalgol]

I tried defining structs for a music database where tracks reference the album they belong to, and I get a cryptic build error.

use turbosql::Turbosql;

#[derive(Turbosql, Default)]
struct Album {
    rowid: Option<i64>,
    title: Option<String>,
    date: Option<String>,
    artist: Option<String>,
}

#[derive(Turbosql, Default)]
struct Track {
    rowid: Option<i64>,
    album: Option<Album>,
    disc_number: Option<i32>,
    track_number: Option<i32>,
    track_title: Option<String>,
}

fn main() {
    let track = Track {
        album: Some(Album{
            title: Some("CVI".to_string()),
            date: Some("2012-05-22".to_string()),
            artist: Some("Royal Thunder".to_string()),
            ..Default::default()
        }),
        disc_number: Some(1),
        track_number: Some(2),
        track_title: Some("Whispering World".to_string()),
        ..Default::default()
    }.insert();
}

$ cargo build
   Compiling turbosql-example v0.1.0 (/path/to/turbosql-example)
error[E0433]: failed to resolve: use of undeclared crate or module `serde_json`
  --> src/main.rs:14:12
   |
14 |     album: Option<Album>,
   |            ^^^^^^ use of undeclared crate or module `serde_json`

For more information about this error, try `rustc --explain E0433`.
error: could not compile `turbosql-example` due to previous error

If I add serde and serde_json to my Cargo.toml, that error is replaced by another.

$ cargo build
   Compiling turbosql-example v0.1.0 (/path/to/turbosql-example)
error[E0277]: the trait bound `Album: Serialize` is not satisfied
    --> src/main.rs:14:5
     |
14   |     album: Option<Album>,
     |     ^^^^^^^------
     |     |      |
     |     |      required by a bound introduced by this call
     |     the trait `Serialize` is not implemented for `Album`
     |
     = note: required because of the requirements on the impl of `Serialize` for `Option<Album>`
note: required by a bound in `serde_json::to_string`
    --> /home/aidan/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/serde_json-1.0.87/src/ser.rs:2141:17
     |
2141 |     T: ?Sized + Serialize,
     |                 ^^^^^^^^^ required by this bound in `serde_json::to_string`

For more information about this error, try `rustc --explain E0277`.
error: could not compile `turbosql-example` due to previous error

[trevyn]

Doing #[derive(serde::Serialize)] on Album could get you closer, but that still might not be exactly what you want.

There isn’t great support for automating foreign keys etc. yet, so if you want those to be two separate cross-referenced tables, you’ll need to treat them as separate flat tables and add rowid references manually.