Hands-On Microservices with Rust

Creating a connections pool

To connect to a database, we extract the connection URL from the --database command-line argument. If it isn't set, we use the mongodb://localhost:27017/admin default value:

let addr = matches.value_of("database")    .unwrap_or("mongodb://localhost:27017/admin");let url = Url::parse(addr)?;

But we also parse it to the Url struct. This is necessary because MongoDB connections expect options sets to be collected by separate values:

let opts = ConnectionOptionsBuilder::new()    .with_host(url.host_str().unwrap_or("localhost"))    .with_port(url.port().unwrap_or(27017))    .with_db(&url.path()[1..])    .build();let manager = MongodbConnectionManager::new(opts);let pool = Pool::builder()    .max_size(4)    .build(manager)?;let conn = pool.get()?; ...