fix mysql TinyInt serialization

fixes #91

Author: 0xdeafbeef

src/mysql/serialize.rs

@@ -12,7 +12,7 @@ pub(super) struct ToSqlHelper {
 fn to_value((metadata, bind): (MysqlType, Option<Vec<u8>>)) -> Value {
     match bind {
         Some(bind) => match metadata {
-            MysqlType::Tiny => Value::Int(bind[0] as _),
+            MysqlType::Tiny => Value::Int((bind[0] as i8) as i64),
             MysqlType::Short => Value::Int(i16::from_ne_bytes(bind.try_into().unwrap()) as _),
             MysqlType::Long => Value::Int(i32::from_ne_bytes(bind.try_into().unwrap()) as _),
             MysqlType::LongLong => Value::Int(i64::from_ne_bytes(bind.try_into().unwrap())),

tests/type_check.rs

@@ -67,6 +67,36 @@ async fn check_tiny_int() {
     type_check::<_, sql_types::TinyInt>(conn, -1_i8).await;
     type_check::<_, sql_types::TinyInt>(conn, i8::MIN).await;
     type_check::<_, sql_types::TinyInt>(conn, i8::MAX).await;
+
+    #[derive(QueryableByName, Debug)]
+    #[diesel(table_name = test_small)]
+    struct Test {
+        id: i8,
+    }
+
+    table!(test_small(id){
+        id -> TinyInt,
+    });
+
+    // test case for https://github.com/weiznich/diesel_async/issues/91
+    diesel::sql_query("drop table if exists test_small")
+        .execute(conn)
+        .await
+        .unwrap();
+    diesel::sql_query("create table test_small(id smallint primary key)")
+        .execute(conn)
+        .await
+        .unwrap();
+    diesel::sql_query("insert into test_small(id) values(-1)")
+        .execute(conn)
+        .await
+        .unwrap();
+    let got = diesel::sql_query("select id from test_small where id = ?")
+        .bind::<sql_types::TinyInt, _>(-1)
+        .load::<Test>(conn)
+        .await
+        .unwrap();
+    assert_eq!(got[0].id, -1);
 }
 
 #[cfg(feature = "mysql")]