Add todos CLI example for postgres

Cargo.toml

@@ -3,7 +3,8 @@ members = [
     ".",
     "sqlx-core",
     "sqlx-macros",
-    "examples/realworld-postgres"
+    "examples/realworld-postgres",
+    "examples/todos-postgres",
 ]
 
 [package]

examples/todos-postgres/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "todos-postgres"
+version = "0.1.0"
+edition = "2018"
+workspace = "../../"
+
+[dependencies]
+anyhow = "1.0"
+async-std = { version = "1.4.0", features = [ "attributes" ] }
+futures = "0.3"
+paw = "1.0"
+sqlx = { version = "0.2", features = ["postgres"] }
+structopt = { version = "0.3", features = ["paw"] }

examples/todos-postgres/README.md

@@ -0,0 +1,29 @@
+# TODOs Example
+
+## Usage
+
+Declare the database URL:
+
+```
+export DATABASE_URL="postgres://postgres@localhost/todos"
+```
+
+Create the database:
+
+```
+createdb -U postgres todos
+```
+
+Load the database schema:
+
+```
+psql -d "$DATABASE_URL" -f ./schema.sql
+```
+
+Run:
+
+- Add a todo: `cargo run -- add "todo description"`
+- Complete a todo: `cargo run -- done <todo id>`
+- List all todos: `cargo run`
+
+

examples/todos-postgres/schema.sql

@@ -0,0 +1,5 @@
+CREATE TABLE IF NOT EXISTS todos (
+    id          BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+    description TEXT NOT NULL,
+    done        BOOLEAN DEFAULT FALSE
+);

examples/todos-postgres/src/main.rs

@@ -0,0 +1,111 @@
+use sqlx::PgPool;
+use std::env;
+use structopt::StructOpt;
+
+#[derive(StructOpt)]
+struct Args {
+    #[structopt(subcommand)]
+    cmd: Option<Command>,
+}
+
+#[derive(StructOpt)]
+enum Command {
+    Add { description: String },
+    Done { id: i64 },
+}
+
+#[async_std::main]
+#[paw::main]
+async fn main(args: Args) -> anyhow::Result<()> {
+    let mut pool = PgPool::new(&env::var("DATABASE_URL")?).await?;
+
+    match args.cmd {
+        Some(Command::Add { description }) => {
+            println!("Adding new todo with description '{}'", &description);
+            println!(
+                "Added new todo with id {}",
+                add_todo(&pool, &description).await.unwrap()
+            );
+        }
+        Some(Command::Done { id }) => {
+            println!("Marking todo {} as done", id);
+            if complete_todo(&pool, id).await.unwrap() {
+                println!("Todo {} is marked as done", id);
+            } else {
+                println!("Invalid id {}", id);
+            }
+        }
+        None => {
+            println!("Printing list of all todos");
+            list_todos(&mut pool).await.unwrap();
+        }
+    }
+
+    pool.close().await;
+
+    Ok(())
+}
+
+async fn add_todo(pool: &PgPool, description: &str) -> Result<i64, sqlx::error::Error> {
+    let mut tx = pool.begin().await?;
+
+    let rec = sqlx::query!(
+        r#"
+INSERT INTO todos ( description )
+VALUES ( $1 )
+RETURNING id
+        "#,
+        description.to_string()
+    )
+    .fetch_one(&mut tx)
+    .await?;
+
+    tx.commit().await?;
+
+    Ok(rec.id)
+}
+
+async fn complete_todo(pool: &PgPool, id: i64) -> Result<bool, sqlx::error::Error> {
+    let mut tx = pool.begin().await?;
+
+    let rows_affected = sqlx::query!(
+        r#"
+UPDATE todos
+SET done = TRUE
+WHERE id = $1
+        "#,
+        id
+    )
+    .execute(&mut tx)
+    .await?;
+
+    tx.commit().await?;
+
+    Ok(rows_affected > 0)
+}
+
+async fn list_todos(pool: &mut PgPool) -> Result<(), sqlx::error::Error> {
+    let recs = sqlx::query!(
+        r#"
+SELECT id, description, done
+FROM todos
+ORDER BY id
+        "#
+    )
+    .fetch_all(pool)
+    .await?;
+
+    for rec in recs {
+        println!(
+            "- [{}] {}: {}",
+            match rec.done {
+                true => "x",  // Done
+                false => " ", // Not Done
+            },
+            rec.id,
+            &rec.description,
+        );
+    }
+
+    Ok(())
+}