restructure folders

templating/tinytemplate/Cargo.toml

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+[package]
+name = "template-tinytemplate"
+version = "1.0.0"
+edition = "2021"
+
+[dependencies]
+env_logger = "0.9.0"
+tinytemplate = "1.1"
+actix-web = "4.0.0-beta.21"
+serde_json = "1"

templating/tinytemplate/README.md

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+# template_tinytemplate
+
+See the documentation for the minimalist template engine [tiny_template](https://docs.rs/tinytemplate/1.1.0/tinytemplate/).
+
+## Usage
+
+### Server
+
+```bash
+cd template_engines/tinytemplate
+cargo run # (or ``cargo watch -x run``)
+# Started http server: 127.0.0.1:8080
+```
+
+### 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

templating/tinytemplate/src/main.rs

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+use std::collections::HashMap;
+
+use actix_web::body::BoxBody;
+use actix_web::dev::ServiceResponse;
+use actix_web::http::header::ContentType;
+use actix_web::http::StatusCode;
+use actix_web::middleware::{ErrorHandlerResponse, ErrorHandlers};
+use actix_web::{error, middleware, web, App, Error, HttpResponse, HttpServer, Result};
+use serde_json::json;
+use tinytemplate::TinyTemplate;
+
+// store tiny_template in application state
+async fn index(
+    tmpl: web::Data<TinyTemplate<'_>>,
+    query: web::Query<HashMap<String, String>>,
+) -> Result<HttpResponse, Error> {
+    let s = if let Some(name) = query.get("name") {
+        // submitted form
+        let ctx = json!({
+          "name" : name.to_owned(),
+          "text" : "Welcome!".to_owned()
+        });
+        tmpl.render("user.html", &ctx)
+            .map_err(|_| error::ErrorInternalServerError("Template error"))?
+    } else {
+        tmpl.render("index.html", &serde_json::Value::Null)
+            .map_err(|_| error::ErrorInternalServerError("Template error"))?
+    };
+    Ok(HttpResponse::Ok().content_type("text/html").body(s))
+}
+
+#[actix_web::main]
+async fn main() -> std::io::Result<()> {
+    std::env::set_var("RUST_LOG", "actix_web=info");
+    env_logger::init();
+
+    HttpServer::new(|| {
+        let mut tt = TinyTemplate::new();
+        tt.add_template("index.html", INDEX).unwrap();
+        tt.add_template("user.html", USER).unwrap();
+        tt.add_template("error.html", ERROR).unwrap();
+
+        App::new()
+            .app_data(web::Data::new(tt))
+            .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<BoxBody> {
+    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<BoxBody>> {
+    let response = get_error_response(&res, "Page not found");
+    Ok(ErrorHandlerResponse::Response(ServiceResponse::new(
+        res.into_parts().0,
+        response.map_into_left_body(),
+    )))
+}
+
+// Generic error handler.
+fn get_error_response<B>(res: &ServiceResponse<B>, error: &str) -> HttpResponse {
+    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| {
+        HttpResponse::build(res.status())
+            .content_type(ContentType::plaintext())
+            .body(e.to_string())
+    };
+
+    let tt = request
+        .app_data::<web::Data<TinyTemplate<'_>>>()
+        .map(|t| t.get_ref());
+    match tt {
+        Some(tt) => {
+            let mut context = std::collections::HashMap::new();
+            context.insert("error", error.to_owned());
+            context.insert("status_code", res.status().as_str().to_owned());
+            let body = tt.render("error.html", &context);
+
+            match body {
+                Ok(body) => HttpResponse::build(res.status())
+                    .content_type(ContentType::html())
+                    .body(body),
+                Err(_) => fallback(error),
+            }
+        }
+        None => fallback(error),
+    }
+}
+
+static ERROR: &str = include_str!("../templates/error.html");
+static INDEX: &str = include_str!("../templates/index.html");
+static USER: &str = include_str!("../templates/user.html");

templating/tinytemplate/templates/error.html

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+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8" />
+    <title>{error}</title>
+  </head>
+  <body>
+    <h1>{status_code} {error}</h1>
+  </body>
+</html>

templating/tinytemplate/templates/index.html

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+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8" />
+  <title>Actix Web</title>
+</head>
+<body>
+  <h1>Welcome!</h1>
+  <p>
+    <h3>What is your name?</h3>
+    <form>
+      <input type="text" name="name" /><br/>
+      <p><input type="submit"></p>
+    </form>
+  </p>
+</body>
+</html>

templating/tinytemplate/templates/user.html

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+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8" />
+    <title>Actix Web</title>
+  </head>
+  <body>
+    <h1>Hi, {name}!</h1>
+    <p>{text}</p>
+  </body>
+</html>