How to properly use UUID with sqlx?

[marknefedov]

I have a query that returns single UUID value, but it looks like there is need from some special handling for converting UUID from Row.

sqlx = { version = "0.5", features = [
    "runtime-tokio-rustls",
    "postgres",
    "chrono",
    "uuid",
] }


let id = sqlx::query_as::<_, Uuid>(
            "INSERT INTO users (name, password, email) VALUES ($1, $2, $3) RETURNING id",
        )
        .bind(name)
        .bind(password)
        .bind(email)
        .fetch_one(&self.pool)

error[E0277]: the trait bound `for<'r> Uuid: FromRow<'r, _>` is not satisfied
   --> src/pg_store.rs:23:18
    |
23  |         let id = sqlx::query_as::<_, Uuid>(
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `for<'r> FromRow<'r, _>` is not implemented for `Uuid`
    |

[marknefedov]

@jplatte Answered in discord:
query_as is for getting a type that implements FromRow, not Type
What you need if you just want the single column of the output is query_scalar
You could also use a one-tuple, but that's kind of ugly which is why there is query_scalar

let (id,) = sqlx::query_as::<_, (Uuid,)>(
    "INSERT INTO users (name, password, email) VALUES ($1, $2, $3) RETURNING id",
)
.bind(...)
.fetch_one(&self.pool)
.await?;

[Tienisto]

To extend @marknefedov answer:

Scalar:

let id = sqlx::query_scalar::<_, Uuid>(
    "INSERT INTO users (name, password, email) VALUES ($1, $2, $3) RETURNING id",
)
.bind(...)
.fetch_one(&pool)
.await?;

Tuple:

let (id,) = sqlx::query_as::<_, (Uuid,)>(
    "INSERT INTO users (name, password, email) VALUES ($1, $2, $3) RETURNING id",
)
.bind(...)
.fetch_one(&pool)
.await?;