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flatten for optionals #2934
Description
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
};
Activity
pravic commentedon Apr 1, 2024
I've stumbled upon a series of
Optionin a query result type and wanted to refactor it into a single flattenedOption<Inner>only to realize that this is not supported insqlx, unlike inserde(playground).But this should be easy, shouldn't it?
enhancement: (transact-rs#2934) implement FromRow for Option<T> where…
transact-rs#2934 solution using autoref trick instead of blanket impl…