Can't decode nullable values

[SorenHolstHansen]

I have found these related issues/pull requests

#367

Description

sqlx fails to decode any column when the column is nullable.

Reproduction steps

Say i have the following setup in my database

CREATE TABLE table_a (id UUID NOT NULL UNIQUE DEFAULT gen_random_uuid(), name TEXT NOT NULL);

CREATE TABLE table_b (id UUID NOT NULL UNIQUE DEFAULT gen_random_uuid(), name TEXT NOT NULL, thing TEXT, table_a_id UUID);

ALTER TABLE table_b ADD CONSTRAINT table_b_table_a_id FOREIGN KEY (table_a_id) REFERENCES table_a(id) ON DELETE CASCADE ON UPDATE CASCADE;

INSERT INTO table_b (name) VALUES ('name');

Then running the following program

use sqlx::postgres::PgPoolOptions;

#[tokio::main]
async fn main() -> Result<(), sqlx::Error> {
    let pool = PgPoolOptions::new()
        .connect("postgres://postgres:postgres@localhost:5432/testing")
        .await?;

    let row = sqlx::query(
        "
        SELECT
            t.id,
            t.name,
	    t.thing,
            t.table_a_id
        FROM table_b t
        ",
    )
    .fetch_one(&pool)
    .await?;

    println!("ROW {:?}", row);

    Ok(())
}

Prints the following (I have formatted it for readability)

ROW PgRow {
	id: 1f0ae783-4bc1-4424-8605-89e67815f56d, 
	name: "name", 
	thing: (error decoding SQL type TEXT as alloc::string::String: UnexpectedNullError), 
	table_a_id: (error decoding SQL type UUID as uuid::Uuid: UnexpectedNullError)
}

SQLx version

0.8

Enabled SQLx features

runtime-tokio-rustls, postgres, json, uuid

Database server and version

Postgres

Operating system

MacOS

Rust version

1.82.0