add conditional put

http-server/src/handlers/update_account.rs

@@ -1,9 +1,7 @@
-use actix_web::{put, web, HttpResponse, Responder, Result};
+use actix_web::{put, web, HttpRequest, HttpResponse, Responder, Result};
 use bank::account::AccountError;
 use serde::Serialize;
 
-use bank::bank::Bank;
-
 use crate::handlers::error::HttpAccountError;
 use crate::handlers::AmountData;
 use crate::AppState;
@@ -18,6 +16,7 @@ pub async fn route(
     info: web::Path<String>,
     form: web::Form<AmountData>,
     data: web::Data<AppState>,
+    req: HttpRequest,
 ) -> Result<impl Responder> {
     let nr = info.into_inner();
     let amount = form.amount;
@@ -29,11 +28,22 @@ pub async fn route(
     info!("updating account {}...", nr);
 
     let bank = data.bank.read().unwrap();
-    match Bank::account_action(bank, &nr, |account| {
-        account.balance = amount;
-        Ok(amount)
-    }) {
-        Err(e) => Err(HttpAccountError(e).into()),
-        Ok(_) => Ok(HttpResponse::Ok().finish()),
+    match bank.accounts.get(&nr) {
+        None => Err(HttpAccountError(AccountError::NotFound).into()),
+        Some(account) => {
+            let mut account = account.write().unwrap();
+            let hash = account.hash_string();
+            if let Some(etag) = req.headers().get("If-Match") {
+                let etag = etag.to_str().unwrap_or("");
+                if etag != hash {
+                    Ok(HttpResponse::PreconditionFailed().finish())
+                } else {
+                    account.balance = amount;
+                    Ok(HttpResponse::Ok().finish())
+                }
+            } else {
+                Ok(HttpResponse::PreconditionRequired().finish())
+            }
+        }
     }
 }

http-server/src/main.rs

@@ -155,6 +155,30 @@ mod tests {
             .set_form(&payload)
             .to_request();
         let resp = test::call_service(&app, req).await;
+        assert_eq!(resp.status(), StatusCode::PRECONDITION_REQUIRED);
+
+        let payload = AmountData { amount: 10_f64 };
+        let req = test::TestRequest::put()
+            .uri(&format!("/accounts/{}", nr))
+            .append_header((actix_web::http::header::IF_MATCH, "I aspire to be an etag"))
+            .set_form(&payload)
+            .to_request();
+        let resp = test::call_service(&app, req).await;
+        assert_eq!(resp.status(), StatusCode::PRECONDITION_FAILED);
+
+        let acc = bank::account::Account {
+            number: nr.to_string(),
+            owner: "aaa".to_string(),
+            balance: 5_f64,
+            is_active: true
+        };
+        let payload = AmountData { amount: 10_f64 };
+        let req = test::TestRequest::put()
+            .uri(&format!("/accounts/{}", nr))
+            .append_header((actix_web::http::header::IF_MATCH, acc.hash_string()))
+            .set_form(&payload)
+            .to_request();
+        let resp = test::call_service(&app, req).await;
         assert!(resp.status().is_success());
 
         let req = test::TestRequest::put()