Merge pull request #323 from pfrenssen/error-pages-using-templates

Demonstrate how to access templating engines in app_data() to render HTML error pages
actix · May 20, 2020 · e4b94fc · e4b94fc
2 parents 2d3ee94 + a790fd7
commit e4b94fc
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Showing 8 changed files with 128 additions and 4 deletions.
diff --git a/template_handlebars/Cargo.toml b/template_handlebars/Cargo.toml
@@ -5,7 +5,8 @@ authors = ["Alexandru Tiniuc <[email protected]>"]
 edition = "2018"
 
 [dependencies]
-actix-web = "2.0.0"
+actix-http = "1.0.1"
 actix-rt = "1.0.0"
+actix-web = "2.0.0"
 handlebars = { version = "3.0.0", features = ["dir_source"] }
 serde_json = "1.0"
diff --git a/template_handlebars/src/README.md → template_handlebars/README.md b/template_handlebars/src/README.md → template_handlebars/README.md
@@ -5,3 +5,4 @@ This is an example of how to use Actix Web with the [Handlebars templating langu
 - http://localhost:8080
 - http://localhost:8080/Emma/documents
 - http://localhost:8080/Bob/passwords
+- http://localhost:8080/some-non-existing-page - 404 error rendered using template
diff --git a/template_handlebars/src/main.rs b/template_handlebars/src/main.rs
@@ -4,8 +4,11 @@ extern crate actix_web;
 #[macro_use]
 extern crate serde_json;
 
-use actix_web::web;
-use actix_web::{App, HttpResponse, HttpServer};
+use actix_http::{body::Body, Response};
+use actix_web::dev::ServiceResponse;
+use actix_web::http::StatusCode;
+use actix_web::middleware::errhandlers::{ErrorHandlerResponse, ErrorHandlers};
+use actix_web::{web, App, HttpResponse, HttpServer, Result};
 
 use handlebars::Handlebars;
 
@@ -49,6 +52,7 @@ async fn main() -> io::Result<()> {
 
     HttpServer::new(move || {
         App::new()
+            .wrap(error_handlers())
             .app_data(handlebars_ref.clone())
             .service(index)
             .service(user)
@@ -57,3 +61,50 @@ async fn main() -> io::Result<()> {
     .run()
     .await
 }
+
+// Custom error handlers, to return HTML responses when an error occurs.
+fn error_handlers() -> ErrorHandlers<Body> {
+    ErrorHandlers::new().handler(StatusCode::NOT_FOUND, not_found)
+}
+
+// Error handler for a 404 Page not found error.
+fn not_found<B>(res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
+    let response = get_error_response(&res, "Page not found");
+    Ok(ErrorHandlerResponse::Response(
+        res.into_response(response.into_body()),
+    ))
+}
+
+// Generic error handler.
+fn get_error_response<B>(res: &ServiceResponse<B>, error: &str) -> Response<Body> {
+    let request = res.request();
+
+    // Provide a fallback to a simple plain text response in case an error occurs during the
+    // rendering of the error page.
+    let fallback = |e: &str| {
+        Response::build(res.status())
+            .content_type("text/plain")
+            .body(e.to_string())
+    };
+
+    let hb = request
+        .app_data::<web::Data<Handlebars>>()
+        .map(|t| t.get_ref());
+    match hb {
+        Some(hb) => {
+            let data = json!({
+                "error": error,
+                "status_code": res.status().as_str()
+            });
+            let body = hb.render("error", &data);
+
+            match body {
+                Ok(body) => Response::build(res.status())
+                    .content_type("text/html")
+                    .body(body),
+                Err(_) => fallback(error),
+            }
+        }
+        None => fallback(error),
+    }
+}
diff --git a/template_handlebars/static/templates/error.html b/template_handlebars/static/templates/error.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8" />
+  <title>{{error}}</title>
+</head>
+<body>
+  <h1>{{status_code}} {{error}}</h1>
+</body>
+</html>
diff --git a/template_tera/Cargo.toml b/template_tera/Cargo.toml
@@ -8,5 +8,6 @@ edition = "2018"
 [dependencies]
 env_logger = "0.7"
 tera = "1.0"
+actix-http = "1.0.1"
 actix-web = "2.0.0"
 actix-rt = "1.0.0"
diff --git a/template_tera/README.md b/template_tera/README.md
@@ -15,3 +15,4 @@ cargo run (or ``cargo watch -x run``)
 ### web client
 
 - [http://localhost:8080](http://localhost:8080)
+- [http://localhost:8080/non-existing-page](http://localhost:8080/non-existing-page) - 404 page rendered using template
diff --git a/template_tera/src/main.rs b/template_tera/src/main.rs
@@ -1,6 +1,10 @@
 use std::collections::HashMap;
 
-use actix_web::{error, middleware, web, App, Error, HttpResponse, HttpServer};
+use actix_http::{body::Body, Response};
+use actix_web::dev::ServiceResponse;
+use actix_web::http::StatusCode;
+use actix_web::middleware::errhandlers::{ErrorHandlerResponse, ErrorHandlers};
+use actix_web::{error, middleware, web, App, Error, HttpResponse, HttpServer, Result};
 use tera::Tera;
 
 // store tera template in application state
@@ -35,8 +39,53 @@ async fn main() -> std::io::Result<()> {
             .data(tera)
             .wrap(middleware::Logger::default()) // enable logger
             .service(web::resource("/").route(web::get().to(index)))
+            .service(web::scope("").wrap(error_handlers()))
     })
     .bind("127.0.0.1:8080")?
     .run()
     .await
 }
+
+// Custom error handlers, to return HTML responses when an error occurs.
+fn error_handlers() -> ErrorHandlers<Body> {
+    ErrorHandlers::new().handler(StatusCode::NOT_FOUND, not_found)
+}
+
+// Error handler for a 404 Page not found error.
+fn not_found<B>(res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
+    let response = get_error_response(&res, "Page not found");
+    Ok(ErrorHandlerResponse::Response(
+        res.into_response(response.into_body()),
+    ))
+}
+
+// Generic error handler.
+fn get_error_response<B>(res: &ServiceResponse<B>, error: &str) -> Response<Body> {
+    let request = res.request();
+
+    // Provide a fallback to a simple plain text response in case an error occurs during the
+    // rendering of the error page.
+    let fallback = |e: &str| {
+        Response::build(res.status())
+            .content_type("text/plain")
+            .body(e.to_string())
+    };
+
+    let tera = request.app_data::<web::Data<Tera>>().map(|t| t.get_ref());
+    match tera {
+        Some(tera) => {
+            let mut context = tera::Context::new();
+            context.insert("error", error);
+            context.insert("status_code", res.status().as_str());
+            let body = tera.render("error.html", &context);
+
+            match body {
+                Ok(body) => Response::build(res.status())
+                    .content_type("text/html")
+                    .body(body),
+                Err(_) => fallback(error),
+            }
+        }
+        None => fallback(error),
+    }
+}
diff --git a/template_tera/templates/error.html b/template_tera/templates/error.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8" />
+  <title>{{ error }}</title>
+</head>
+<body>
+  <h1>{{ status_code }} {{ error }}</h1>
+</body>
+</html>