Update 'databases' example README.

The README now more completely documents the example.

All implementations now make use of 'RETURNING'.

examples/databases/.sqlx/query-3c289da9873097a11191dbedc5c78d86afd6a6d36771bfeb12f331abca6279cf.json

@@ -1,12 +0,0 @@
-{
-  "db_name": "SQLite",
-  "query": "INSERT INTO posts (title, text) VALUES (?, ?)",
-  "describe": {
-    "columns": [],
-    "parameters": {
-      "Right": 2
-    },
-    "nullable": []
-  },
-  "hash": "3c289da9873097a11191dbedc5c78d86afd6a6d36771bfeb12f331abca6279cf"
-}

examples/databases/.sqlx/query-bea4ef6e25064f6b383e854f8bc2770d89cfaf9859d0bfca78b2ca24627675b7.json

@@ -0,0 +1,20 @@
+{
+  "db_name": "SQLite",
+  "query": "INSERT INTO posts (title, text) VALUES (?, ?) RETURNING id",
+  "describe": {
+    "columns": [
+      {
+        "name": "id",
+        "ordinal": 0,
+        "type_info": "Int64"
+      }
+    ],
+    "parameters": {
+      "Right": 2
+    },
+    "nullable": [
+      false
+    ]
+  },
+  "hash": "bea4ef6e25064f6b383e854f8bc2770d89cfaf9859d0bfca78b2ca24627675b7"
+}

examples/databases/Cargo.toml

@@ -7,7 +7,7 @@ publish = false
 
 [dependencies]
 rocket = { path = "../../core/lib", features = ["json"] }
-diesel = "2"
+diesel = { version = "2", features = ["returning_clauses_for_sqlite_3_35"] }
 diesel_migrations = "2"
 
 [dependencies.sqlx]

examples/databases/README.md

@@ -1,8 +1,69 @@
 # Databases Example
 
-This example makes use of SQLite. You'll need `sqlite3` and its development
-headers installed:
+This example makes use of SQLite and MySQL. You'll need `sqlite3` and a MySQL
+client installed:
 
-  * **macOS:** `brew install sqlite`
-  * **Debian**, **Ubuntu:** `apt-get install libsqlite3-dev`
-  * **Arch:** `pacman -S sqlite`
+  * **macOS:** `brew install sqlite mysql-client`
+  * **Debian**, **Ubuntu:** `apt-get install libsqlite3-dev libmysqlclient-dev`
+  * **Arch:** `pacman -S sqlite libmysqlclient`
+
+## API Implementation
+
+This example implements a JSON-based HTTP API for a "blog" using several database drivers:
+
+  * `sqlx` (`/sqlx`, `sqlx.rs`)
+  * `rusqlite` (`/rusqlite`, `rusqlite.rs`)
+  * `diesel` (sqlite) (`/diesel`, `diesel_sqlite.rs`)
+  * `diesel-async` (mysql) (`/diesel-async`, `diesel_mysql.rs`)
+
+The exposed API is succinctly described as follows, with
+[`httpie`](https://httpie.io/) CLI examples:
+
+  * `POST /driver`: create post via JSON with `title` and `text`; returns new
+    post JSON with new `id`
+
+        http http://127.0.0.1:8000/sqlx title="Title" text="Hello, world."
+        > { "id": 2128, "text": "Hello, world.", "title": "Title" }
+
+  * `GET /driver`: returns JSON array of IDs for blog posts
+
+        http http://127.0.0.1:8000/sqlx
+        > [ 2128, 2129, 2130, 2131 ]
+
+  * `GET /driver/<id>`: returns a JSON object for the post with id `<id>`
+
+        http http://127.0.0.1:8000/sqlx/2128
+        > { "id": 2128, "text": "Hello, world.", "title": "Title" }
+
+  * `DELETE /driver`: delete all posts
+
+        http delete http://127.0.0.1:8000/sqlx
+
+  * `DELETE /driver/<id>`: delete post with id `<id>`
+
+        http delete http://127.0.0.1:8000/sqlx/4
+
+## Migrations
+
+Database migrations are stored in the respective `db/${driver}` directory.
+
+### `diesel`
+
+Diesel migrations are found in `db/diesel/migrations`. They are run
+automatically. They can be run manually as well:
+
+```sh
+cargo install diesel_cli --no-default-features --features sqlite
+DATABASE_URL="db/diesel/db.sqlite" diesel migration --migration-dir db/diesel/migrations redo
+```
+
+### `sqlx`
+
+sqlx migrations are found in `db/sqlx/migrations`. They are run automatically.
+
+Query metadata for offline checking was prepared with the following commands:
+
+```sh
+cargo install sqlx-cli --no-default-features --features sqlite
+DATABASE_URL="sqlite:$(pwd)/db/sqlx/db.sqlite" cargo sqlx prepare
+```

examples/databases/src/diesel_mysql.rs

@@ -92,6 +92,6 @@ async fn destroy(mut db: Connection<Db>) -> Result<()> {
 pub fn stage() -> AdHoc {
     AdHoc::on_ignite("Diesel SQLite Stage", |rocket| async {
         rocket.attach(Db::init())
-            .mount("/diesel-async/", routes![list, read, create, delete, destroy])
+            .mount("/diesel-async", routes![list, read, create, delete, destroy])
     })
 }

examples/databases/src/diesel_sqlite.rs

@@ -32,14 +32,16 @@ table! {
 }
 
 #[post("/", data = "<post>")]
-async fn create(db: Db, post: Json<Post>) -> Result<Created<Json<Post>>> {
+async fn create(db: Db, mut post: Json<Post>) -> Result<Created<Json<Post>>> {
     let post_value = post.clone();
-    db.run(move |conn| {
+    let id: Option<i32> = db.run(move |conn| {
         diesel::insert_into(posts::table)
             .values(&*post_value)
-            .execute(conn)
+            .returning(posts::id)
+            .get_result(conn)
     }).await?;
 
+    post.id = Some(id.expect("returning guarantees id present"));
     Ok(Created::new("/").body(post))
 }
 

examples/databases/src/rusqlite.rs

@@ -22,13 +22,15 @@ struct Post {
 type Result<T, E = Debug<rusqlite::Error>> = std::result::Result<T, E>;
 
 #[post("/", data = "<post>")]
-async fn create(db: Db, post: Json<Post>) -> Result<Created<Json<Post>>> {
+async fn create(db: Db, mut post: Json<Post>) -> Result<Created<Json<Post>>> {
     let item = post.clone();
-    db.run(move |conn| {
-        conn.execute("INSERT INTO posts (title, text) VALUES (?1, ?2)",
-            params![item.title, item.text])
+    let id = db.run(move |conn| {
+        conn.query_row("INSERT INTO posts (title, text) VALUES (?1, ?2) RETURNING id",
+            params![item.title, item.text],
+            |r| r.get(0))
     }).await?;
 
+    post.id = Some(id);
     Ok(Created::new("/").body(post))
 }
 

examples/databases/src/sqlx.rs

@@ -23,12 +23,13 @@ struct Post {
 }
 
 #[post("/", data = "<post>")]
-async fn create(mut db: Connection<Db>, post: Json<Post>) -> Result<Created<Json<Post>>> {
-    // There is no support for `RETURNING`.
-    sqlx::query!("INSERT INTO posts (title, text) VALUES (?, ?)", post.title, post.text)
-        .execute(&mut **db)
-        .await?;
+async fn create(mut db: Connection<Db>, mut post: Json<Post>) -> Result<Created<Json<Post>>> {
+    let query = sqlx::query! {
+        "INSERT INTO posts (title, text) VALUES (?, ?) RETURNING id",
+        post.title, post.text
+    };
 
+    post.id = Some(query.fetch_one(&mut **db).await?.id);
     Ok(Created::new("/").body(post))
 }