new type support in query_as #2369

0xdeafbeef · 2023-02-23T00:14:20Z

use sqlx::PgPool;


struct Wrap(bigdecimal::BigDecimal);

impl From<bigdecimal::BigDecimal> for Wrap {
    fn from(x: bigdecimal::BigDecimal) -> Self {
        Wrap(x)
    }
}

impl From<Wrap> for bigdecimal::BigDecimal {
    fn from(x: Wrap) -> Self {
        x.0
    }
}

struct Data {
    pub amount: Wrap,
}


#[tokio::main]
async fn main() {
    let db = PgPool::connect("postgres://postgres:mysecretpassword@localhost:5432/teststore").await.unwrap();

    sqlx::query_as!(Data, "select amount from test").fetch_one(&db).await.unwrap();
    // previously it will expand like this:
     {
         {
             #[allow(clippy::all)] {
                 use ::sqlx::Arguments   as _;
                 let query_args = <sqlx::postgres::Postgres as ::sqlx::database::HasArguments>::Arguments::default();
                 ::sqlx::query_with::<sqlx::postgres::Postgres, _>("select amount from test", query_args).try_map(|row: sqlx::postgres::PgRow| {
                     use ::sqlx::Row   as _;
                     let sqlx_query_as_amount = row.try_get_unchecked::<sqlx::types::BigDecimal, _>(0usize)?;
                     Ok(Data { r#amount: sqlx_query_as_amount })
                 })
             }
         }
     }

 now it will expand like this:

let sqlx_query_as_amount = row.try_get_unchecked::<sqlx::types::BigDecimal, _>(0usize)?.into(); <-----

This change shouldn't break anything, because From<T> is implemented for T.

Maybe we can also use From for binded arguments in sqlx::query

example:

let t = "string";
sqlx::query!("select $1",  t)

Here we can use t.into() internally, but it can break inference

abonander · 2023-02-23T20:52:28Z

There was a reason I didn't do this and I believe it had to do with compile errors. Can you test what happens when you try to use an incompatible type?

0xdeafbeef · 2023-02-23T21:48:41Z

There was a reason I didn't do this and I believe it had to do with compile errors. Can you test what happens when you try to use an incompatible type?

   |
27 |     sqlx::query_as!(Record2,r#"select 1 as "amount!""#).fetch_one(&db).await.unwrap();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<i32>` is not implemented for `std::string::String`
   |
   = help: the following other types implement trait `From<T>`:
             <std::string::String as From<&mut str>>
             <std::string::String as From<&std::string::String>>
             <std::string::String as From<&str>>
             <std::string::String as From<Box<str>>>
             <std::string::String as From<Cow<'a, str>>>
             <std::string::String as From<char>>
             <std::string::String as From<url::Url>>
   = note: required for `i32` to implement `Into<std::string::String>`
   = note: this error originates in the macro `$crate::sqlx_macros::expand_query` which comes from the expansion of the macro `sqlx::query_as` (in Nightly builds, run with -Z macro-backtrace for more info)

I'll try to add some type checking to make errors more obvious.

The current error looks like this:

  --> src/main.rs:27:5
   |
27 |     sqlx::query_as!(Record2, r#"select 1 as "amount!""#).fetch_one(&db).await.unwrap();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |     |
   |     expected struct `std::string::String`, found `i32`
   |     help: try using a conversion method: `.to_string()`
   |
   = note: this error originates in the macro `$crate::sqlx_macros::expand_query` which comes from the expansion of the macro `sqlx::query_as` (in Nightly builds, run with -Z macro-backtrace for more info)

abonander · 2023-02-23T21:50:32Z

Yeah, neither error is great. Something I want to do shortly but won't make the 0.7.0 release is rewrite the typechecking code entirely so that it also works with FromRow. I figure I can use panic!() messages in const to give much more useful error messages.

CosmicHorrorDev · 2023-02-23T23:01:04Z

rewrite the typechecking code entirely so that it also works with FromRow. I figure I can use panic!() messages in const to give much more useful error messages.

Yes please! Both using FromRow and giving better error messages would be amazing!

abonander · 2023-03-04T03:50:16Z

The annoying part is that panic!() in const doesn't support formatting AFAIK, so I'd have to use a dirty hack like the following: https://github.com/Vurich/const-concat

As-implemented, I think that macro would trigger #[deny(unsafe_code)] if the user has it set. I think it can be cleaned up with const-generics though.

abonander · 2023-03-04T03:56:04Z

I suppose concatenation isn't really necessary as I could just emit two different consts per check, e.g.:

const _: () = panic!("field `foo` of struct `Bar` expected type `i32`");
const _: () = panic!("column `foo` of query has SQL type `TEXT`");

gives something like:

   Compiling playground v0.0.1 (/playground)
error[[E0080]](https://doc.rust-lang.org/stable/error_codes/E0080.html): evaluation of constant value failed
 --> src/lib.rs:1:15
  |
1 | const _: () = panic!("field `foo` of struct `Bar` expected type `i32`");
  |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'field `foo` of struct `Bar` expected type `i32`', src/lib.rs:1:15
  |
  = note: this error originates in the macro `$crate::panic::panic_2021` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)

error[[E0080]](https://doc.rust-lang.org/stable/error_codes/E0080.html): evaluation of constant value failed
 --> src/lib.rs:2:15
  |
2 | const _: () = panic!("column `foo` of query has SQL type `TEXT`");
  |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'column `foo` of query has SQL type `TEXT`', src/lib.rs:2:15
  |
  = note: this error originates in the macro `$crate::panic::panic_2021` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0080`.
error: could not compile `playground` due to 2 previous errors

The formatting isn't ideal but at least all the relevant information is there.

heksesang · 2023-09-06T11:15:48Z

Is this feature supposed to work for Options?

beyarkay · 2024-01-16T12:15:25Z

For future travellers, these sqlx docs solved my problem. Basically:

#[derive(sqlx::Type)]
#[sqlx(transparent)]
struct UserId(i64);

0xdeafbeef added 2 commits February 23, 2023 00:48

fix: sqlx-postgres bigdecimal feature

6198e62

feat: support new types in sqlx::query_as!

ce88ca3

0xdeafbeef changed the title ~~fix: sqlx-postgres bigdecimal feature~~ new type support in query_as Feb 23, 2023

0xdeafbeef force-pushed the main branch 2 times, most recently from 4166e9f to f99264f Compare February 23, 2023 11:40

fix test

5405852

0xdeafbeef force-pushed the main branch from f99264f to 5405852 Compare February 23, 2023 12:50

abonander merged commit 5a8cd95 into launchbadge:main Mar 9, 2023

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new type support in query_as #2369

new type support in query_as #2369

0xdeafbeef commented Feb 23, 2023

abonander commented Feb 23, 2023

0xdeafbeef commented Feb 23, 2023

abonander commented Feb 23, 2023

CosmicHorrorDev commented Feb 23, 2023

abonander commented Mar 4, 2023

abonander commented Mar 4, 2023 •

edited

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heksesang commented Sep 6, 2023

beyarkay commented Jan 16, 2024

new type support in query_as #2369

new type support in query_as #2369

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0xdeafbeef commented Feb 23, 2023

abonander commented Feb 23, 2023

0xdeafbeef commented Feb 23, 2023

abonander commented Feb 23, 2023

CosmicHorrorDev commented Feb 23, 2023

abonander commented Mar 4, 2023

abonander commented Mar 4, 2023 • edited Loading

heksesang commented Sep 6, 2023

beyarkay commented Jan 16, 2024

abonander commented Mar 4, 2023 •

edited

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