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flatten for optionals #2934

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cemoktra opened this issue Dec 13, 2023 · 1 comment · May be fixed by #3667
Open

flatten for optionals #2934

cemoktra opened this issue Dec 13, 2023 · 1 comment · May be fixed by #3667
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enhancement New feature or request

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@cemoktra
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cemoktra commented Dec 13, 2023 •
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Is your feature request related to a problem? Please describe.
When selecting multiple columns from a left outer join (optional) i might get a set of 5 optional fields which i want to have in one optional struct that is none if nothing to join.

Describe the solution you'd like

#[derive(FromRow)]
struct DbRow {
  id_of_main_table: Uuid,
  otherstuff: (),
  #[sqlx(flatten)]
  inner: Option<Joined>
}

#[derive(FromRow)]
struct Joined {
  id_of_join: Uuid,
  more_joined_stuff: ()
}

Describe alternatives you've considered
Alternatives are having all fields optional and writing a huge tuple match to convert into an optional struct or use a helper crate like tuple_combinator

The manual approach would like:

#[derive(FromRow)]
struct DbRow {
  id_of_main_table: Uuid,
  otherstuff: (),
  //
  id_of_join: Option<Uuid>,
  more_joined_stuff: Option<()>,
}

// some conversion like
let joined = if let (Some(id_of_join),  Some(more_joined_stuff)) = (id_of_join, more_joined_stuff) {
  Some(Joined {
    id_of_join,
    more_joined_stuff
  })
} else {
  None
};
@cemoktra cemoktra added the enhancement New feature or request label Dec 13, 2023
@pravic
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pravic commented Apr 1, 2024

I've stumbled upon a series of Option in a query result type and wanted to refactor it into a single flattened Option<Inner> only to realize that this is not supported in sqlx, unlike in serde (playground).

But this should be easy, shouldn't it?

jonnyso added a commit to jonnyso/sqlx that referenced this issue Jan 5, 2025
@jonnyso
enhancement: (launchbadge#2934) implement FromRow for Option<T> where…
2003e26 
… T: FromRow
@jonnyso jonnyso linked a pull request Jan 5, 2025 that will close this issue
Open
jonnyso added a commit to jonnyso/sqlx that referenced this issue Jan 8, 2025
@jonnyso
launchbadge#2934 solution using autoref trick instead of blanket impl…
4d9f292 
…ementation for Option<T>
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@pravic @cemoktra