Add support for the Datetime type for MySQL

This is mostly the same as for the Timestamp type so I reused both FromSql and
ToSql implementations.

Author: Eijebong

CHANGELOG.md

@@ -22,6 +22,8 @@ for Rust libraries in [RFC #1105](https://github.com/rust-lang/rfcs/blob/master/
 
 * Added support for the [Range][range-0.16.0] type on postgreSQL.
 
+* Added support for the Datetime type on MySQL.
+
 * `infer_schema!` will now automatically detect which tables can be joined based
   on the presence of foreign key constraints.
 

diesel/src/mysql/types/date_and_time.rs

@@ -8,7 +8,7 @@ use std::os::raw as libc;
 use std::{ptr, mem, slice};
 
 use mysql::Mysql;
-use types::{ToSql, ToSqlOutput, FromSql, IsNull, Timestamp, Time, Date};
+use types::{ToSql, ToSqlOutput, FromSql, IsNull, Timestamp, Time, Date, Datetime};
 
 macro_rules! mysql_time_impls {
     ($ty:ty) => {
@@ -41,10 +41,24 @@ macro_rules! mysql_time_impls {
     }
 }
 
+mysql_time_impls!(Datetime);
+primitive_impls!(Datetime -> NaiveDateTime);
 mysql_time_impls!(Timestamp);
 mysql_time_impls!(Time);
 mysql_time_impls!(Date);
 
+impl ToSql<Datetime, Mysql> for NaiveDateTime {
+    fn to_sql<W: Write>(&self, out: &mut ToSqlOutput<W, Mysql>) -> Result<IsNull, Box<Error+Send+Sync>> {
+        <NaiveDateTime as ToSql<Timestamp, Mysql>>::to_sql(self, out)
+    }
+}
+
+impl FromSql<Datetime, Mysql> for NaiveDateTime {
+    fn from_sql(bytes: Option<&[u8]>) -> Result<Self, Box<Error+Send+Sync>> {
+        <NaiveDateTime as FromSql<Timestamp, Mysql>>::from_sql(bytes)
+    }
+}
+
 impl ToSql<Timestamp, Mysql> for NaiveDateTime {
     fn to_sql<W: Write>(&self, out: &mut ToSqlOutput<W, Mysql>) -> Result<IsNull, Box<Error+Send+Sync>> {
         let mut mysql_time: ffi::MYSQL_TIME = unsafe { mem::zeroed() };
@@ -134,7 +148,7 @@ mod tests {
     use expression::dsl::{sql, now};
     use prelude::*;
     use select;
-    use types::{Date, Time, Timestamp};
+    use types::{Date, Time, Timestamp, Datetime};
 
     fn connection() -> MysqlConnection {
         dotenv().ok();
@@ -152,6 +166,8 @@ mod tests {
         let time = NaiveDate::from_ymd(1970, 1, 1).and_hms(0, 0, 0);
         let query = select(sql::<Timestamp>("CAST('1970-01-01' AS DATETIME)").eq(time));
         assert!(query.get_result::<bool>(&connection).unwrap());
+        let query = select(sql::<Datetime>("CAST('1970-01-01' AS DATETIME)").eq(time));
+        assert!(query.get_result::<bool>(&connection).unwrap());
     }
 
     #[test]
@@ -161,6 +177,9 @@ mod tests {
         let epoch_from_sql = select(sql::<Timestamp>("CAST('1970-01-01' AS DATETIME)"))
             .get_result(&connection);
         assert_eq!(Ok(time), epoch_from_sql);
+        let epoch_from_sql = select(sql::<Datetime>("CAST('1970-01-01' AS DATETIME)"))
+            .get_result(&connection);
+        assert_eq!(Ok(time), epoch_from_sql);
     }
 
     #[test]

diesel/src/mysql/types/mod.rs

@@ -62,6 +62,12 @@ impl HasSqlType<::types::Timestamp> for Mysql {
     }
 }
 
+impl HasSqlType<Datetime> for Mysql {
+    fn metadata(_: &()) -> MysqlType {
+        MysqlType::DateTime
+    }
+}
+
 impl HasSqlType<::types::Numeric> for Mysql {
     fn metadata(_: &()) -> MysqlType {
         MysqlType::String
@@ -76,3 +82,15 @@ impl QueryId for ::types::Numeric {
         true
     }
 }
+
+/// Represents the MySQL datetime type.
+/// ### [`ToSql`](/diesel/types/trait.ToSql.html) impls
+///
+/// - [`chrono::NaiveDateTime`][NaiveDateTime] with `feature = "chrono"`
+///
+/// ### [`FromSql`](/diesel/types/trait.FromSql.html) impls
+///
+/// - [`chrono::NaiveDateTime`][NaiveDateTime] with `feature = "chrono"`
+///
+/// [NaiveDateTime]: https://lifthrasiir.github.io/rust-chrono/chrono/naive/datetime/struct.NaiveDateTime.html
+#[derive(Debug, Clone, Copy, Default)] pub struct Datetime;

diesel_tests/tests/types_roundtrip.rs

@@ -193,6 +193,7 @@ mod mysql_types {
 
     test_round_trip!(i8_roundtrips, Tinyint, i8);
     test_round_trip!(naive_datetime_roundtrips, Timestamp, (i64, u32), mk_naive_datetime);
+    test_round_trip!(naive_datetime_roundtrips_to_datetime, Datetime, (i64, u32), mk_naive_datetime);
     test_round_trip!(naive_time_roundtrips, Time, (u32, u32), mk_naive_time);
     test_round_trip!(naive_date_roundtrips, Date, u32, mk_naive_date);
     test_round_trip!(bigdecimal_roundtrips, Numeric, (i64, u64), mk_bigdecimal);