doc: How to map Payload back to struct?

[gitmalong]

Hi!

What is the proper way to go from select() ->Payload to a custom struct?

I could not find any examples regarding that and the doc does also not mention it.

Thanks

[gitmalong]

I found that this works but I am not sure whether this is the best way to do so.

let selected = table("settings")
    .select()
    .filter("year = 2023")
    .execute(&mut glue)
    .await
    .unwrap();
        
match selected {
  gluesql_core::prelude::Payload::Select { labels, rows } => {
      let time_zone_i = labels.iter().position(|x| x == "time_zone").unwrap();
      let currency = labels.iter().position(|x| x == "currency").unwrap();
      Settings {
          currency: rows[0][currency].clone().into(),
          time_zone: rows[0][time_zone_i].clone().into(),
      } 
  },
  _ => panic!(),
}

[Jiseok CHOI]

Try using Payload::Select if you have a schema, or Payload::SelectMap if you don't, to fetch rows.

My recommendation is to create a struct and implement TryFrom for Payload and struct
e.g) ever0de@a0ccda2#diff-6ecd13eab89cbf9d6f327f55c2a4a177059a5407406d3560a1bf07862a2b36fdR11

struct MyTable {
	rows: Vec<Row>
}

impl TryFrom<Payload> for MyTable {
    // ...
}


let mut payloads = glue.execute("SELECT * FROM Table;").unwrap();
let payload = payloads.remove(0);
let table: MyTable = payload.try_into().unwrap();
// ...

[gitmalong]

Thanks! How can I provoke getting a SelectMap from my select query builder?

[Jiseok CHOI]

The return values of the AstBuilder::execute and Glue::execute functions are similar.

• https://docs.rs/gluesql/latest/gluesql/core/ast_builder/trait.Execute.html
• https://docs.rs/gluesql/latest/gluesql/prelude/struct.Glue.html#method.execute

You can remove Vec::remove from the above example, because you get Payload instead of Vec<Payload>.

[gitmalong]

Thanks for the hints. A macro like https://docs.rs/sqlx/latest/sqlx/trait.FromRow.html would be useful to derive impl TryFrom<Payload> for MyTable for common types.