feat: Text adapter (#2894)

Cargo.toml

@@ -345,4 +345,3 @@ required-features = ["postgres", "macros", "migrate"]
 name = "postgres-migrate"
 path = "tests/postgres/migrate.rs"
 required-features = ["postgres", "macros", "migrate"]
-

sqlx-core/Cargo.toml

@@ -92,5 +92,5 @@ event-listener = "2.5.2"
 dotenvy = "0.15"
 
 [dev-dependencies]
-sqlx = { workspace = true, features = ["postgres", "sqlite", "mysql", "migrate", "macros"] }
+sqlx = { workspace = true, features = ["postgres", "sqlite", "mysql", "migrate", "macros", "time", "uuid"] }
 tokio = { version = "1", features = ["rt"] }

sqlx-core/src/types/mod.rs

@@ -28,6 +28,8 @@ pub mod bstr;
 #[cfg_attr(docsrs, doc(cfg(feature = "json")))]
 mod json;
 
+mod text;
+
 #[cfg(feature = "uuid")]
 #[cfg_attr(docsrs, doc(cfg(feature = "uuid")))]
 #[doc(no_inline)]
@@ -81,6 +83,8 @@ pub mod mac_address {
 #[cfg(feature = "json")]
 pub use json::{Json, JsonRawValue, JsonValue};
 
+pub use text::Text;
+
 /// Indicates that a SQL type is supported for a database.
 ///
 /// ## Compile-time verification

sqlx-core/src/types/text.rs

@@ -0,0 +1,134 @@
+use std::ops::{Deref, DerefMut};
+
+/// Map a SQL text value to/from a Rust type using [`Display`] and [`FromStr`].
+///
+/// This can be useful for types that do not have a direct SQL equivalent, or are simply not
+/// supported by SQLx for one reason or another.
+///
+/// For strongly typed databases like Postgres, this will report the value's type as `TEXT`.
+/// Explicit conversion may be necessary on the SQL side depending on the desired type.
+///
+/// [`Display`]: std::fmt::Display
+/// [`FromStr`]: std::str::FromStr
+///
+/// ### Panics
+///
+/// You should only use this adapter with `Display` implementations that are infallible,
+/// otherwise you may encounter panics when attempting to bind a value.
+///
+/// This is because the design of the `Encode` trait assumes encoding is infallible, so there is no
+/// way to bubble up the error.
+///
+/// Fortunately, most `Display` implementations are infallible by convention anyway
+/// (the standard `ToString` trait also assumes this), but you may still want to audit
+/// the source code for any types you intend to use with this adapter, just to be safe.
+///
+/// ### Example: `SocketAddr`
+///
+/// MySQL and SQLite do not have a native SQL equivalent for `SocketAddr`, so if you want to
+/// store and retrieve instances of it, it makes sense to map it to `TEXT`:
+///
+/// ```rust,no_run
+/// # use sqlx::types::{time, uuid};
+///
+/// use std::net::SocketAddr;
+///
+/// use sqlx::Connection;
+/// use sqlx::mysql::MySqlConnection;
+/// use sqlx::types::Text;
+///
+/// use uuid::Uuid;
+/// use time::OffsetDateTime;
+///
+/// #[derive(sqlx::FromRow, Debug)]
+/// struct Login {
+///     user_id: Uuid,
+///     socket_addr: Text<SocketAddr>,
+///     login_at: OffsetDateTime
+/// }
+///
+/// # async fn example() -> Result<(), Box<dyn std::error::Error>> {
+///
+/// let mut conn: MySqlConnection = MySqlConnection::connect("<DATABASE URL>").await?;
+///
+/// let user_id: Uuid = "e9a72cdc-d907-48d6-a488-c64a91fd063c".parse().unwrap();
+/// let socket_addr: SocketAddr = "198.51.100.47:31790".parse().unwrap();
+///
+/// // CREATE TABLE user_login(user_id VARCHAR(36), socket_addr TEXT, login_at TIMESTAMP);
+/// sqlx::query("INSERT INTO user_login(user_id, socket_addr, login_at) VALUES (?, ?, NOW())")
+///     .bind(user_id)
+///     .bind(Text(socket_addr))
+///     .execute(&mut conn)
+///     .await?;
+///
+/// let logins: Vec<Login> = sqlx::query_as("SELECT * FROM user_login")
+///     .fetch_all(&mut conn)
+///     .await?;
+///
+/// println!("Logins for user ID {user_id}: {logins:?}");
+///
+/// # Ok(())
+/// # }
+/// ```
+#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Text<T>(pub T);
+
+impl<T> Text<T> {
+    /// Extract the inner value.
+    pub fn into_inner(self) -> T {
+        self.0
+    }
+}
+
+impl<T> Deref for Text<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<T> DerefMut for Text<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+/* We shouldn't use blanket impls so individual drivers can provide specialized ones.
+impl<T, DB> Type<DB> for Text<T>
+where
+    String: Type<DB>,
+    DB: Database,
+{
+    fn type_info() -> DB::TypeInfo {
+        String::type_info()
+    }
+
+    fn compatible(ty: &DB::TypeInfo) -> bool {
+        String::compatible(ty)
+    }
+}
+
+impl<'q, T, DB> Encode<'q, DB> for Text<T>
+where
+    T: Display,
+    String: Encode<'q, DB>,
+    DB: Database,
+{
+    fn encode_by_ref(&self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull {
+        self.0.to_string().encode(buf)
+    }
+}
+
+impl<'r, T, DB> Decode<'r, DB> for Text<T>
+where
+    T: FromStr,
+    BoxDynError: From<<T as FromStr>::Err>,
+    &'r str: Decode<'r, DB>,
+    DB: Database,
+{
+    fn decode(value: <DB as HasValueRef<'r>>::ValueRef) -> Result<Self, BoxDynError> {
+        Ok(Text(<&'r str as Decode<'r, DB>>::decode(value)?.parse()?))
+    }
+}
+*/

sqlx-mysql/src/types/mod.rs

@@ -104,6 +104,7 @@ mod bytes;
 mod float;
 mod int;
 mod str;
+mod text;
 mod uint;
 
 #[cfg(feature = "json")]

sqlx-mysql/src/types/text.rs

@@ -0,0 +1,49 @@
+use crate::{MySql, MySqlTypeInfo, MySqlValueRef};
+use sqlx_core::decode::Decode;
+use sqlx_core::encode::{Encode, IsNull};
+use sqlx_core::error::BoxDynError;
+use sqlx_core::types::{Text, Type};
+use std::fmt::Display;
+use std::str::FromStr;
+
+impl<T> Type<MySql> for Text<T> {
+    fn type_info() -> MySqlTypeInfo {
+        <String as Type<MySql>>::type_info()
+    }
+
+    fn compatible(ty: &MySqlTypeInfo) -> bool {
+        <String as Type<MySql>>::compatible(ty)
+    }
+}
+
+impl<'q, T> Encode<'q, MySql> for Text<T>
+where
+    T: Display,
+{
+    fn encode_by_ref(&self, buf: &mut Vec<u8>) -> IsNull {
+        // We can't really do the trick like with Postgres where we reserve the space for the
+        // length up-front and then overwrite it later, because MySQL appears to enforce that
+        // length-encoded integers use the smallest encoding for the value:
+        // https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_basic_dt_integers.html#sect_protocol_basic_dt_int_le
+        //
+        // So we'd have to reserve space for the max-width encoding, format into the buffer,
+        // then figure out how many bytes our length-encoded integer needs to be and move the
+        // value bytes down to use up the empty space.
+        //
+        // Copying from a completely separate buffer instead is easier. It may or may not be faster
+        // or slower depending on a ton of different variables, but I don't currently have the time
+        // to implement both approaches and compare their performance.
+        Encode::<MySql>::encode(self.0.to_string(), buf)
+    }
+}
+
+impl<'r, T> Decode<'r, MySql> for Text<T>
+where
+    T: FromStr,
+    BoxDynError: From<<T as FromStr>::Err>,
+{
+    fn decode(value: MySqlValueRef<'r>) -> Result<Self, BoxDynError> {
+        let s: &str = Decode::<MySql>::decode(value)?;
+        Ok(Self(s.parse()?))
+    }
+}

sqlx-postgres/src/types/array.rs

@@ -1,4 +1,5 @@
 use sqlx_core::bytes::Buf;
+use sqlx_core::types::Text;
 use std::borrow::Cow;
 
 use crate::decode::Decode;
@@ -67,6 +68,16 @@ where
     }
 }
 
+impl<T> PgHasArrayType for Text<T> {
+    fn array_type_info() -> PgTypeInfo {
+        String::array_type_info()
+    }
+
+    fn array_compatible(ty: &PgTypeInfo) -> bool {
+        String::array_compatible(ty)
+    }
+}
+
 impl<T> Type<Postgres> for [T]
 where
     T: PgHasArrayType,

sqlx-postgres/src/types/mod.rs

@@ -193,6 +193,7 @@ mod oid;
 mod range;
 mod record;
 mod str;
+mod text;
 mod tuple;
 mod void;
 

sqlx-postgres/src/types/text.rs

@@ -0,0 +1,50 @@
+use crate::{PgArgumentBuffer, PgTypeInfo, PgValueRef, Postgres};
+use sqlx_core::decode::Decode;
+use sqlx_core::encode::{Encode, IsNull};
+use sqlx_core::error::BoxDynError;
+use sqlx_core::types::{Text, Type};
+use std::fmt::Display;
+use std::str::FromStr;
+
+use std::io::Write;
+
+impl<T> Type<Postgres> for Text<T> {
+    fn type_info() -> PgTypeInfo {
+        <String as Type<Postgres>>::type_info()
+    }
+
+    fn compatible(ty: &PgTypeInfo) -> bool {
+        <String as Type<Postgres>>::compatible(ty)
+    }
+}
+
+impl<'q, T> Encode<'q, Postgres> for Text<T>
+where
+    T: Display,
+{
+    fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> IsNull {
+        // Unfortunately, our API design doesn't give us a way to bubble up the error here.
+        //
+        // Fortunately, writing to `Vec<u8>` is infallible so the only possible source of
+        // errors is from the implementation of `Display::fmt()` itself,
+        // where the onus is on the user.
+        //
+        // The blanket impl of `ToString` also panics if there's an error, so this is not
+        // unprecedented.
+        //
+        // However, the panic should be documented anyway.
+        write!(**buf, "{}", self.0).expect("unexpected error from `Display::fmt()`");
+        IsNull::No
+    }
+}
+
+impl<'r, T> Decode<'r, Postgres> for Text<T>
+where
+    T: FromStr,
+    BoxDynError: From<<T as FromStr>::Err>,
+{
+    fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError> {
+        let s: &str = Decode::<Postgres>::decode(value)?;
+        Ok(Self(s.parse()?))
+    }
+}

sqlx-sqlite/src/types/mod.rs

@@ -124,12 +124,14 @@
 //! over a floating-point type in the first place.
 //!
 //! Instead, you should only use a type affinity that SQLite will not attempt to convert implicitly,
-//! such as `TEXT` or `BLOB`, and map values to/from SQLite as strings.
+//! such as `TEXT` or `BLOB`, and map values to/from SQLite as strings. You can do this easily
+//! using [the `Text` adapter].
+//!
 //!
 //! [`decimal.c`]: https://www.sqlite.org/floatingpoint.html#the_decimal_c_extension
 //! [amalgamation]: https://www.sqlite.org/amalgamation.html
 //! [type-affinity]: https://www.sqlite.org/datatype3.html#type_affinity
-//!
+//! [the `Text` adapter]: Text
 
 pub(crate) use sqlx_core::types::*;
 
@@ -142,6 +144,7 @@ mod int;
 #[cfg(feature = "json")]
 mod json;
 mod str;
+mod text;
 #[cfg(feature = "time")]
 mod time;
 mod uint;

sqlx-sqlite/src/types/text.rs

@@ -0,0 +1,37 @@
+use crate::{Sqlite, SqliteArgumentValue, SqliteTypeInfo, SqliteValueRef};
+use sqlx_core::decode::Decode;
+use sqlx_core::encode::{Encode, IsNull};
+use sqlx_core::error::BoxDynError;
+use sqlx_core::types::{Text, Type};
+use std::fmt::Display;
+use std::str::FromStr;
+
+impl<T> Type<Sqlite> for Text<T> {
+    fn type_info() -> SqliteTypeInfo {
+        <String as Type<Sqlite>>::type_info()
+    }
+
+    fn compatible(ty: &SqliteTypeInfo) -> bool {
+        <String as Type<Sqlite>>::compatible(ty)
+    }
+}
+
+impl<'q, T> Encode<'q, Sqlite> for Text<T>
+where
+    T: Display,
+{
+    fn encode_by_ref(&self, buf: &mut Vec<SqliteArgumentValue<'q>>) -> IsNull {
+        Encode::<Sqlite>::encode(self.0.to_string(), buf)
+    }
+}
+
+impl<'r, T> Decode<'r, Sqlite> for Text<T>
+where
+    T: FromStr,
+    BoxDynError: From<<T as FromStr>::Err>,
+{
+    fn decode(value: SqliteValueRef<'r>) -> Result<Self, BoxDynError> {
+        let s: &str = Decode::<Sqlite>::decode(value)?;
+        Ok(Self(s.parse()?))
+    }
+}