Add SyncConnectionWrapper type around diesel::Connection

Author: momobel

Cargo.toml

@@ -38,6 +38,8 @@ diesel_migrations = "2.1.0"
 default = []
 mysql = ["diesel/mysql_backend", "mysql_async", "mysql_common", "futures-channel", "tokio"]
 postgres = ["diesel/postgres_backend", "tokio-postgres", "tokio", "tokio/rt"]
+sqlite = ["diesel/sqlite", "sync-connection-wrapper"]
+sync-connection-wrapper = ["tokio/rt"]
 async-connection-wrapper = ["tokio/net"]
 r2d2 = ["diesel/r2d2"]
 
@@ -57,6 +59,7 @@ members = [
         ".",
         "examples/postgres/pooled-with-rustls",
         "examples/postgres/run-pending-migrations-with-rustls",
+        "examples/sync-wrapper",
 ]
 
 [patch.crates-io]

examples/sync-wrapper/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "sync-wrapper"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+diesel = { version = "2.1.0", default-features = false }
+diesel-async = { version = "0.4.0", path = "../../", features = ["sync-connection-wrapper", "async-connection-wrapper"] }
+diesel_migrations = "2.1.0"
+futures-util = "0.3.21"
+tokio = { version = "1.2.0", default-features = false, features = ["macros", "rt-multi-thread"] }
+
+[features]
+default = ["sqlite"]
+sqlite = ["diesel-async/sqlite"]

examples/sync-wrapper/diesel.toml

@@ -0,0 +1,9 @@
+# For documentation on how to configure this file,
+# see https://diesel.rs/guides/configuring-diesel-cli
+
+[print_schema]
+file = "src/schema.rs"
+custom_type_derives = ["diesel::query_builder::QueryId"]
+
+[migrations_directory]
+dir = "migrations"

examples/sync-wrapper/migrations/.keep

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS users;

examples/sync-wrapper/migrations/00000000000000_diesel_initial_setup/down.sql

@@ -0,0 +1,3 @@
+CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT);
+
+INSERT INTO users(id, name) VALUES(123, 'hello world');

examples/sync-wrapper/migrations/00000000000000_diesel_initial_setup/up.sql

@@ -0,0 +1,88 @@
+use diesel::prelude::*;
+use diesel::sqlite::{Sqlite, SqliteConnection};
+use diesel_async::async_connection_wrapper::AsyncConnectionWrapper;
+use diesel_async::sync_connection_wrapper::SyncConnectionWrapper;
+use diesel_async::{AsyncConnection, RunQueryDsl, SimpleAsyncConnection};
+use diesel_migrations::{embed_migrations, EmbeddedMigrations, MigrationHarness};
+
+// ordinary diesel model setup
+
+table! {
+    users {
+        id -> Integer,
+        name -> Text,
+    }
+}
+
+#[derive(Debug, Queryable, Selectable)]
+#[diesel(table_name = users)]
+struct User {
+    id: i32,
+    name: String,
+}
+
+const MIGRATIONS: EmbeddedMigrations = embed_migrations!();
+
+type InnerConnection = SqliteConnection;
+
+type InnerDB = Sqlite;
+
+async fn establish(db_url: &str) -> ConnectionResult<SyncConnectionWrapper<InnerConnection>> {
+    SyncConnectionWrapper::<SqliteConnection>::establish(db_url).await
+}
+
+async fn run_migrations<A>(async_connection: A) -> Result<(), Box<dyn std::error::Error>>
+where
+    A: AsyncConnection<Backend = InnerDB> + 'static,
+{
+    let mut async_wrapper: AsyncConnectionWrapper<A> =
+        AsyncConnectionWrapper::from(async_connection);
+
+    tokio::task::spawn_blocking(move || {
+        async_wrapper.run_pending_migrations(MIGRATIONS).unwrap();
+    })
+    .await
+    .map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let db_url = std::env::var("DATABASE_URL").expect("Env var `DATABASE_URL` not set");
+
+    // create an async connection for the migrations
+    let sync_wrapper: SyncConnectionWrapper<InnerConnection> = establish(&db_url).await?;
+    run_migrations(sync_wrapper).await?;
+
+    let mut sync_wrapper: SyncConnectionWrapper<InnerConnection> = establish(&db_url).await?;
+
+    sync_wrapper.batch_execute("DELETE FROM users").await?;
+
+    sync_wrapper
+        .batch_execute("INSERT INTO users(id, name) VALUES (3, 'toto')")
+        .await?;
+
+    let data: Vec<User> = users::table
+        .select(User::as_select())
+        .load(&mut sync_wrapper)
+        .await?;
+    println!("{data:?}");
+
+    diesel::delete(users::table)
+        .execute(&mut sync_wrapper)
+        .await?;
+
+    diesel::insert_into(users::table)
+        .values((users::id.eq(1), users::name.eq("iLuke")))
+        .execute(&mut sync_wrapper)
+        .await?;
+
+    let data: Vec<User> = users::table
+        .filter(users::id.gt(0))
+        .or_filter(users::name.like("%Luke"))
+        .select(User::as_select())
+        .load(&mut sync_wrapper)
+        .await?;
+    println!("{data:?}");
+
+    Ok(())
+}

examples/sync-wrapper/src/main.rs

@@ -93,6 +93,8 @@ pub mod pg;
 pub mod pooled_connection;
 mod run_query_dsl;
 mod stmt_cache;
+#[cfg(feature = "sync-connection-wrapper")]
+pub mod sync_connection_wrapper;
 mod transaction_manager;
 
 #[cfg(feature = "mysql")]