Encode/Decode impl for Cow<'_, str>

resolves launchbadge#1214

sqlx-core/src/postgres/types/str.rs

@@ -4,6 +4,8 @@ use crate::error::BoxDynError;
 use crate::postgres::types::array_compatible;
 use crate::postgres::{PgArgumentBuffer, PgTypeInfo, PgValueRef, Postgres};
 use crate::types::Type;
+use std::borrow::Cow;
+use crate::database::{HasArguments, HasValueRef};
 
 impl Type<Postgres> for str {
     fn type_info() -> PgTypeInfo {
@@ -22,6 +24,16 @@ impl Type<Postgres> for str {
     }
 }
 
+impl Type<Postgres> for Cow<'_, str> {
+    fn type_info() -> PgTypeInfo {
+        <&str as Type<Postgres>>::type_info()
+    }
+
+    fn compatible(ty: &PgTypeInfo) -> bool {
+        <&str as Type<Postgres>>::compatible(ty)
+    }
+}
+
 impl Type<Postgres> for [&'_ str] {
     fn type_info() -> PgTypeInfo {
         PgTypeInfo::TEXT_ARRAY
@@ -50,6 +62,15 @@ impl Encode<'_, Postgres> for &'_ str {
     }
 }
 
+impl Encode<'_, Postgres> for Cow<'_, str> {
+    fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull {
+        match self {
+            Cow::Borrowed(str) => str.encode(buf),
+            Cow::Owned(str) => <&str as Encode<Postgres>>::encode(&**str, buf)
+        }
+    }
+}
+
 impl Encode<'_, Postgres> for String {
     fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull {
         <&str as Encode<Postgres>>::encode(&**self, buf)
@@ -62,6 +83,12 @@ impl<'r> Decode<'r, Postgres> for &'r str {
     }
 }
 
+impl<'r> Decode<'r, Postgres> for Cow<'r, str> {
+    fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError> {
+        Ok(Cow::Borrowed(value.as_str()?))
+    }
+}
+
 impl Type<Postgres> for String {
     fn type_info() -> PgTypeInfo {
         <&str as Type<Postgres>>::type_info()