query_as! macro gives an error "trait From<i8> is not implemented for bool"

[JohnTheCoolingFan]

Bug Description

When using the query_as! macro with a struct that has a bool field, an error gets thrown saying that bool does not implement trait From<i8>.

Minimal Reproduction

sqlx::query!("CREATE TABLE test_table (test_bool_value BOOL NOT NULL)").execute(&pool).await.unwrap();

struct TestStruct {
    test_bool_value: bool,
}

let test_val = sqlx::query_as!(TestStruct, "SELECT test_bool_value FROM test_table").fetch_one(&pool).await.unwrap();

Info

• SQLx version: 0.7.2
• SQLx features enabled: runtime-tokio, tls-rustls, chrono, mysql
• Database server and version: MariaDB 11.1.2
• Operating system: Arch Linux x86_64
• rustc --version: rustc 1.72.1 (d5c2e9c34 2023-09-13)

[JohnTheCoolingFan]

Error was encountered in currently unpushed code when transitioning from methods to macros. Code I was trying to change is here: https://github.com/JohnTheCoolingFan/sayless/blob/118b1976d46eee71e625994839a11bb5cec42e6f/src/routes/create_link.rs#L23

[abonander]

This isn't really a bug, the behavior is intended just not well documented.

The problem is, all MySQL/MariaDB tells us is that the column is a TINYINT, as that's what it aliases BOOL/BOOLEAN to. We have no way to tell the difference from the wire protocol itself.

In this case, we could simply pull up the table definition, but that only works if the value actually originates from a table column and isn't generated by an expression.

The only real solution would be to put in the work to actually analyze (not just parse) the query itself, which would be quite the ordeal, and isn't even in the cards right now.

Not even #2648 would fix this as bool doesn't implement TryFrom<i8>.

I would recommend just using a type override in the query: https://docs.rs/sqlx/latest/sqlx/macro.query.html#force-a-differentcustom-type

For brevity, you could use a wildcard override: https://docs.rs/sqlx/latest/sqlx/macro.query_as.html#column-type-override-infer-from-struct-field

Alternatively, you could try query_as_unchecked!().