Update may-minihttp to use serde_derive for json (#3903)

frameworks/Rust/may-minihttp/Cargo.toml

@@ -6,6 +6,7 @@ authors = ["Xudong Huang <[email protected]>"]
 [dependencies]
 num_cpus = "1.0"
 serde = "1.0"
+serde_derive = "1.0"
 serde_json = "1.0"
 may = { git = "https://github.com/Xudong-Huang/may" }
 may_minihttp = { git = "https://github.com/Xudong-Huang/may_minihttp" }

frameworks/Rust/may-minihttp/src/main.rs

@@ -1,12 +1,18 @@
 extern crate may;
 extern crate num_cpus;
 #[macro_use]
+extern crate serde_derive;
 extern crate serde_json;
 extern crate may_minihttp;
 
 use std::io;
 use may_minihttp::{HttpServer, HttpService, Request, Response};
 
+#[derive(Serialize)]
+struct Message<'a> {
+    message: &'a str,
+}
+
 struct Techempower;
 
 impl HttpService for Techempower {
@@ -18,7 +24,7 @@ impl HttpService for Techempower {
             "/json" => {
                 resp.header("Content-Type", "application/json");
                 *resp.body_mut() =
-                    serde_json::to_vec(&json!({"message": "Hello, World!"})).unwrap();
+                    serde_json::to_vec(&Message { message: "Hello, World!" }).unwrap();
             }
             "/plaintext" => {
                 resp.header("Content-Type", "text/plain")