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Commitc7a5af3

Browse files
committed
Implement FromSql for tuples up to length 4
This makes it very ergonomic to decode the results of a query like SELECT (1, 'a')where (1, 'a') is returned as an anonymous record type.The big downside to this approach is that only built-in OIDs aresupported, as there is no way to know ahead of time what OIDs will bereturned, and so we'll only have metadata for the built-in OIDs lyingaround.
1 parent598fc0f commitc7a5af3

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2 files changed

+109
-0
lines changed
  • postgres-types/src
  • tokio-postgres/tests/test/types

2 files changed

+109
-0
lines changed

‎postgres-types/src/lib.rs‎

Lines changed: 56 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -617,6 +617,62 @@ impl<'a> FromSql<'a> for IpAddr {
617617
accepts!(INET);
618618
}
619619

620+
macro_rules! impl_from_sql_tuple{
621+
($n:expr; $($ty_ident:ident),*; $($var_ident:ident),*) =>{
622+
impl<'a, $($ty_ident),*>FromSql<'a>for($($ty_ident,)*)
623+
where
624+
$($ty_ident:FromSql<'a>),*
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{
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fn from_sql(
627+
_:&Type,
628+
mut raw:&'a[u8],
629+
) ->Result<($($ty_ident,)*),Box<dynError +Sync +Send>>{
630+
let num_fields = private::read_be_i32(&mut raw)?;
631+
if num_fieldsasusize != $n{
632+
returnErr(format!(
633+
"Postgres record field count does not match Rust tuple length: {} vs {}",
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num_fields,
635+
$n,
636+
).into());
637+
}
638+
639+
$(
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let oid = private::read_be_i32(&mut raw)?asu32;
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let ty =matchType::from_oid(oid){
642+
None =>{
643+
returnErr(format!(
644+
"cannot decode OID {} inside of anonymous record",
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oid,
646+
).into());
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}
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Some(ty)if !$ty_ident::accepts(&ty) =>{
649+
returnErr(Box::new(WrongType::new::<$ty_ident>(ty.clone())));
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}
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Some(ty) => ty,
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};
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let $var_ident = private::read_value(&ty,&mut raw)?;
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)*
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656+
Ok(($($var_ident,)*))
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}
658+
659+
fn accepts(ty:&Type) ->bool{
660+
match ty.kind(){
661+
Kind::Pseudo =>*ty ==Type::RECORD,
662+
Kind::Composite(fields) => fields.len() == $n,
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_ =>false,
664+
}
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}
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}
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};
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}
669+
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impl_from_sql_tuple!(0;;);
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impl_from_sql_tuple!(1;T0; v0);
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impl_from_sql_tuple!(2;T0,T1; v0, v1);
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impl_from_sql_tuple!(3;T0,T1,T2; v0, v1, v2);
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impl_from_sql_tuple!(4;T0,T1,T2,T3; v0, v1, v2, v3);
675+
620676
/// An enum representing the nullability of a Postgres value.
621677
pubenumIsNull{
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/// The value is NULL.

‎tokio-postgres/tests/test/types/mod.rs‎

Lines changed: 53 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -547,6 +547,59 @@ async fn composite() {
547547
}
548548
}
549549

550+
#[tokio::test]
551+
asyncfntuples(){
552+
let client =connect("user=postgres").await;
553+
554+
let row = client.query_one("SELECT ROW()",&[]).await.unwrap();
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let val:() = row.get(0);
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assert_eq!(val,());
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558+
let row = client.query_one("SELECT ROW(1)",&[]).await.unwrap();
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let val:(i32,) = row.get(0);
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assert_eq!(val,(1,));
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let row = client.query_one("SELECT (1, 'a')",&[]).await.unwrap();
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let val:(i32,String) = row.get(0);
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assert_eq!(val,(1,"a".into()));
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566+
let row = client.query_one("SELECT (1, (2, 3))",&[]).await.unwrap();
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let val:(i32,(i32,i32)) = row.get(0);
568+
assert_eq!(val,(1,(2,3)));
569+
570+
let row = client.query_one("SELECT (1, 2)",&[]).await.unwrap();
571+
let err = row.try_get::<_,(i32,String)>(0).unwrap_err();
572+
match err.source(){
573+
Some(e)if e.is::<WrongType>() =>{}
574+
_ =>panic!("Unexpected error {:?}", err),
575+
};
576+
577+
let row = client.query_one("SELECT (1, 2, 3)",&[]).await.unwrap();
578+
let err = row.try_get::<_,(i32,i32)>(0).unwrap_err();
579+
assert_eq!(
580+
err.to_string(),
581+
"error deserializing column 0:\
582+
Postgres record field count does not match Rust tuple length: 3 vs 2"
583+
);
584+
585+
client
586+
.batch_execute(
587+
"CREATE TYPE pg_temp.simple AS (
588+
a int,
589+
b text
590+
)",
591+
)
592+
.await
593+
.unwrap();
594+
595+
let row = client
596+
.query_one("SELECT (1, 'a')::simple",&[])
597+
.await
598+
.unwrap();
599+
let val:(i32,String) = row.get(0);
600+
assert_eq!(val,(1,"a".into()));
601+
}
602+
550603
#[tokio::test]
551604
asyncfnenum_(){
552605
let client =connect("user=postgres").await;

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