Implement HasTable for Option<T> where T: HasTable
#4899
Closed
LucaCappelletti94
started this conversation in
Ideas
Replies: 2 comments 2 replies
|
Thanks for filling this proposal. Could you provide an example of the boilerplate that can be removed by having this impl? |
2 replies
|
In |
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To provide a concrete example, generic code for impl<Error, Conn, T> InsertOptionTuple<Error, Conn> for (Option<T>,)
where
T: RecursiveBuilderInsert<Error, Conn> + HasTable,
{
#[inline]
fn insert_option_tuple(
self,
conn: &mut Conn,
) -> BuilderResult<<Self::NestedTables as NestedTables>::OptionalNestedModels, Error> {
Ok((match self.0 {
Some(builder) => Some(builder.recursive_insert(conn)?),
None => None,
},))
}
}
impl<Error, Conn, Head, Tail> InsertOptionTuple<Error, Conn> for (Option<Head>, Tail)
where
Head: RecursiveBuilderInsert<Error, Conn>,
Tail: InsertOptionTuple<Error, Conn>,
(Option<Head>, Tail): HasNestedTables,
Self::NestedTables: NestedTables<
OptionalNestedModels = (
Option<<Head::Table as TableExt>::Model>,
<Tail::NestedTables as NestedTables>::OptionalNestedModels,
),
>,
{
#[inline]
fn insert_option_tuple(
self,
conn: &mut Conn,
) -> BuilderResult<<Self::NestedTables as NestedTables>::OptionalNestedModels, Error> {
Ok((
match self.0 {
Some(builder) => Some(builder.recursive_insert(conn)?),
None => None,
},
self.1.insert_option_tuple(conn)?,
))
}
} |
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Backend
PostgreSQL, MySQL, SQLite, Others
What do you want to add to diesel?
It would be useful if Option automatically forwarded
HasTablewhenT: HasTable.Optiondoes not alter table semantics, so this is a zero-cost, logically valid blanket impl.This improves ergonomics when working with optional model types and avoids unnecessary boilerplate, without introducing any behavioral or compatibility issues.
Implementation notes
No response
Additional details
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