AsyncConnectionWrapper: Implement Deref<Target = C>

This allows us to use an `AsyncConnectionWrapper` instance with sync **and** async queries, which should slightly ease the migration from sync to async.

Author: Turbo87

src/async_connection_wrapper.rs

@@ -101,6 +101,7 @@ pub use self::implementation::AsyncConnectionWrapper;
 
 mod implementation {
     use diesel::connection::{Instrumentation, SimpleConnection};
+    use std::ops::{Deref, DerefMut};
 
     use super::*;
 
@@ -122,6 +123,20 @@ mod implementation {
         }
     }
 
+    impl<C, B> Deref for AsyncConnectionWrapper<C, B> {
+        type Target = C;
+
+        fn deref(&self) -> &Self::Target {
+            &self.inner
+        }
+    }
+
+    impl<C, B> DerefMut for AsyncConnectionWrapper<C, B> {
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            &mut self.inner
+        }
+    }
+
     impl<C, B> diesel::connection::SimpleConnection for AsyncConnectionWrapper<C, B>
     where
         C: crate::SimpleAsyncConnection,

tests/sync_wrapper.rs

@@ -1,9 +1,11 @@
 use diesel::migration::Migration;
-use diesel::prelude::*;
+use diesel::{Connection, IntoSql};
 use diesel_async::async_connection_wrapper::AsyncConnectionWrapper;
 
 #[test]
 fn test_sync_wrapper() {
+    use diesel::RunQueryDsl;
+
     let db_url = std::env::var("DATABASE_URL").unwrap();
     let mut conn = AsyncConnectionWrapper::<crate::TestConnection>::establish(&db_url).unwrap();
 
@@ -12,8 +14,24 @@ fn test_sync_wrapper() {
     assert_eq!(Ok(1), res);
 }
 
+#[tokio::test]
+async fn test_sync_wrapper_async_query() {
+    use diesel_async::{AsyncConnection, RunQueryDsl};
+
+    let db_url = std::env::var("DATABASE_URL").unwrap();
+    let conn = crate::TestConnection::establish(&db_url).await.unwrap();
+    let mut conn = AsyncConnectionWrapper::<_>::from(conn);
+
+    let res = diesel::select(1.into_sql::<diesel::sql_types::Integer>())
+        .get_result::<i32>(&mut conn)
+        .await;
+    assert_eq!(Ok(1), res);
+}
+
 #[tokio::test]
 async fn test_sync_wrapper_under_runtime() {
+    use diesel::RunQueryDsl;
+
     let db_url = std::env::var("DATABASE_URL").unwrap();
     tokio::task::spawn_blocking(move || {
         let mut conn = AsyncConnectionWrapper::<crate::TestConnection>::establish(&db_url).unwrap();