Add example illustrating how to submit an order

This change adds an example that illustrates how to use the crate to
instantiate an Alpaca client object and subsequently submits a limit
order using it.

CHANGELOG.md

@@ -1,5 +1,6 @@
 Unreleased
 ----------
+- Added example illustrating how to submit a limit order
 - Bumped `http-endpoint` dependency to `0.2`
 
 

examples/order.rs

@@ -0,0 +1,34 @@
+// Copyright (C) 2020 Daniel Mueller <[email protected]>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+use apca::api::v2::order;
+use apca::ApiInfo;
+use apca::Client;
+
+use num_decimal::Num;
+
+#[tokio::main]
+async fn main() {
+  // Requires the following environment variables to be present:
+  // - APCA_API_KEY_ID -> your API key
+  // - APCA_API_SECRET_KEY -> your secret key
+  //
+  // Optionally, the following variable is honored:
+  // - APCA_API_BASE_URL -> the API base URL to use (set to
+  //   https://api.alpaca.markets for live trading)
+  let api_info = ApiInfo::from_env().unwrap();
+  let client = Client::new(api_info);
+
+  // Create request for a limit order for AAPL with a limit price of USD
+  // 100.
+  let request = order::OrderReqInit {
+    type_: order::Type::Limit,
+    limit_price: Some(Num::from(100)),
+    ..Default::default()
+  }
+  // We want to go long on AAPL, buying a single share.
+  .init("AAPL", order::Side::Buy, 1);
+
+  let order = client.issue::<order::Post>(request).await.unwrap();
+  println!("Created order {}", order.id.to_hyphenated_ref());
+}