Intro

In this article I will be going to explore Rocket.rs starting with the basics

What is Rocket.rs

A web framework for Rust gear Rust that makes it simple to write fast, type-safe, secure web applications with incredible usability, productivity and performance

Requirements

Lets start by setting up rust

rustup default stable

Lets create the new project

cargo  new  hello-rocket  --bin
cd hello-rocket

Now, add Rocket as a dependency in your Cargo.toml

[dependencies]
rocket = "0.5.0"

Change the src/main.rs file with the following code:

#[macro_use] extern crate rocket;

#[get("/")]
fn index() -> &'static str {
    "Hello, world!"
}

#[launch]
fn rocket() -> _ {
    rocket::build().mount("/", routes![index])
}

One can execute the following command to compile and run the application

cargo run

That’s it rocket is now running and you can access it through http://127.0.0.1:8000

And our Hello World is done.

Rust CRUD API

Now that we done the Hello World application lets spike a bit and create a API based on the following article

This article will teach you how to build a simple CRUD API with Rust using the Rocket framework. We’ll create a RESTful API that runs on a Rocket HTTP server and persists data in an in-memory database. (Check the original article if you want to deep dive)

Setup

Lets start by instantiating a rust project to create our API

mkdir simple-api-rocket
cd simple-api-rocket
cargo init

Let’s add required packages

cargo add rocket@0.5.0-rc.2 --features json
cargo add serde --features derive
cargo add chrono --features serde
cargo add uuid --features v4

• rocket – A web framework for Rust (nightly).
• serde – A generic serialization/deserialization framework.
• chrono – Date and time library for Rust.
• uuid – A library to generate and parse UUIDs in Rust.

Replace the src/main.rs file with the following content:

use rocket::{get, http::Status, serde::json::Json};
use serde::Serialize;

#[macro_use]
extern crate rocket;

#[derive(Serialize)]
pub struct GenericResponse {
    pub status: String,
    pub message: String,
}

#[get("/healthchecker")]
pub async fn health_checker_handler() -> Result<Json<GenericResponse>, Status> {
    const MESSAGE: &str = "Build Simple CRUD API with Rust and Rocket";

    let response_json = GenericResponse {
        status: "success".to_string(),
        message: MESSAGE.to_string(),
    };
    Ok(Json(response_json))
}

#[launch]
fn rocket() -> _ {
    rocket::build().mount("/api", routes![health_checker_handler,])
}

One can execute the following command cargon run and access the following endpoint

• http://127.0.0.1:8000/api/healthchecker

For this exercise we will use a in-memory database available to all the route handlers,
we’ll use Rust’s smart pointer called Arc along with the Mutex.

Create the Model

Create the file model.rs file and add the following code:

use chrono::prelude::*;
use serde::{Deserialize, Serialize};
use std::sync::{Arc, Mutex};

#[allow(non_snake_case)]
#[derive(Debug, Deserialize, Serialize, Clone)]
pub struct Todo {
    pub id: Option<String>,
    pub title: String,
    pub content: String,
    pub completed: Option<bool>,
    pub createdAt: Option<DateTime<Utc>>,
    pub updatedAt: Option<DateTime<Utc>>,
}

pub struct AppState {
    pub todo_db: Arc<Mutex<Vec<Todo>>>,
}

impl AppState {
    pub fn init() -> AppState {
        AppState {
            todo_db: Arc::new(Mutex::new(Vec::new())),
        }
    }
}

#[allow(non_snake_case)]
#[derive(Debug, Deserialize)]
pub struct UpdateTodoSchema {
    pub title: Option<String>,
    pub content: Option<String>,
    pub completed: Option<bool>,
}

This code created a Todo struct and added Serde’s macros on top of it.

The Deserialize and Serialize macros will allow us to convert the struct to and from JSON

Create the API Response Structs

Here, let’s create structs that implement the [derive(Serialize)] macro to enable us to convert structs into JSON objects before returning them to the client.

So, create a response.rs file in the src directory and add the following structs:

use crate::model::Todo;
use serde::Serialize;

#[derive(Serialize)]
pub struct GenericResponse {
    pub status: String,
    pub message: String,
}

#[derive(Serialize, Debug)]
pub struct TodoData {
    pub todo: Todo,
}

#[derive(Serialize, Debug)]
pub struct SingleTodoResponse {
    pub status: String,
    pub data: TodoData,
}

#[derive(Serialize, Debug)]
pub struct TodoListResponse {
    pub status: String,
    pub results: usize,
    pub todos: Vec<Todo>,
}

Implement the CRUD API

• [get("/healthchecker")] – This route will return a simple health checker JSON object.
• [get("/todos?<page>&<limit>")] – This route will return a selected or paginated list of Todo items.
• [post("/todos", data = "<body>")] – This route will add a new Todo item to the data store.
• [get("/todos/<id>")] – This route will retrieve a single Todo item from the in-memory database and return it to the client.
• [patch("/todos/<id>", data = "<body>")] – This route will edit the fields of a Todo item in the data store.
• [delete("/todos/<id>")] – This route will delete a Todo item from the in-memory database.

First things first, create a handler.rs file in the src folder and add the following crates and dependencies.

use crate::{
    model::{AppState, Todo, UpdateTodoSchema},
    response::{GenericResponse, SingleTodoResponse, TodoData, TodoListResponse},
};
use chrono::prelude::*;
use rocket::{
    delete, get, http::Status, patch, post, response::status::Custom, serde::json::Json, State,
};
use uuid::Uuid;

#[get("/healthchecker")]
pub async fn health_checker_handler() -> Result<Json<GenericResponse>, Status> {
    const MESSAGE: &str = "Build Simple CRUD API with Rust and Rocket";

    let response_json = GenericResponse {
        status: "success".to_string(),
        message: MESSAGE.to_string(),
    };
    Ok(Json(response_json))
}

#[get("/todos?<page>&<limit>")]
pub async fn todos_list_handler(
    page: Option<usize>,
    limit: Option<usize>,
    data: &State<AppState>,
) -> Result<Json<TodoListResponse>, Status> {
    let vec = data.todo_db.lock().unwrap();

    let limit = limit.unwrap_or(10);
    let offset = (page.unwrap_or(1) - 1) * limit;

    let todos: Vec<Todo> = vec.clone().into_iter().skip(offset).take(limit).collect();

    let json_response = TodoListResponse {
        status: "success".to_string(),
        results: todos.len(),
        todos,
    };
    Ok(Json(json_response))
}

#[post("/todos", data = "<body>")]
pub async fn create_todo_handler(
    mut body: Json<Todo>,
    data: &State<AppState>,
) -> Result<Json<SingleTodoResponse>, Custom<Json<GenericResponse>>> {
    let mut vec = data.todo_db.lock().unwrap();

    for todo in vec.iter() {
        if todo.title == body.title {
            let error_response = GenericResponse {
                status: "fail".to_string(),
                message: format!("Todo with title: '{}' already exists", todo.title),
            };
            return Err(Custom(Status::Conflict, Json(error_response)));
        }
    }

    let uuid_id = Uuid::new_v4();
    let datetime = Utc::now();

    body.id = Some(uuid_id.to_string());
    body.completed = Some(false);
    body.createdAt = Some(datetime);
    body.updatedAt = Some(datetime);

    let todo = body.to_owned();

    vec.push(body.into_inner());

    let json_response = SingleTodoResponse {
        status: "success".to_string(),
        data: TodoData {
            todo: todo.into_inner(),
        },
    };

    Ok(Json(json_response))
}

#[get("/todos/<id>")]
pub async fn get_todo_handler(
    id: String,
    data: &State<AppState>,
) -> Result<Json<SingleTodoResponse>, Custom<Json<GenericResponse>>> {
    let vec = data.todo_db.lock().unwrap();

    for todo in vec.iter() {
        if todo.id == Some(id.to_owned()) {
            let json_response = SingleTodoResponse {
                status: "success".to_string(),
                data: TodoData { todo: todo.clone() },
            };

            return Ok(Json(json_response));
        }
    }

    let error_response = GenericResponse {
        status: "fail".to_string(),
        message: format!("Todo with ID: {} not found", id),
    };
    Err(Custom(Status::NotFound, Json(error_response)))
}

#[patch("/todos/<id>", data = "<body>")]
pub async fn edit_todo_handler(
    id: String,
    body: Json<UpdateTodoSchema>,
    data: &State<AppState>,
) -> Result<Json<SingleTodoResponse>, Custom<Json<GenericResponse>>> {
    let mut vec = data.todo_db.lock().unwrap();

    for todo in vec.iter_mut() {
        if todo.id == Some(id.clone()) {
            let datetime = Utc::now();
            let title = body.title.to_owned().unwrap_or(todo.title.to_owned());
            let content = body.content.to_owned().unwrap_or(todo.content.to_owned());
            let payload = Todo {
                id: todo.id.to_owned(),
                title: if !title.is_empty() {
                    title
                } else {
                    todo.title.to_owned()
                },
                content: if !content.is_empty() {
                    content
                } else {
                    todo.content.to_owned()
                },
                completed: if body.completed.is_some() {
                    body.completed
                } else {
                    todo.completed
                },
                createdAt: todo.createdAt,
                updatedAt: Some(datetime),
            };
            *todo = payload;

            let json_response = SingleTodoResponse {
                status: "success".to_string(),
                data: TodoData { todo: todo.clone() },
            };
            return Ok(Json(json_response));
        }
    }

    let error_response = GenericResponse {
        status: "fail".to_string(),
        message: format!("Todo with ID: {} not found", id),
    };

    Err(Custom(Status::NotFound, Json(error_response)))
}

#[delete("/todos/<id>")]
pub async fn delete_todo_handler(
    id: String,
    data: &State<AppState>,
) -> Result<Status, Custom<Json<GenericResponse>>> {
    let mut vec = data.todo_db.lock().unwrap();

    for todo in vec.iter_mut() {
        if todo.id == Some(id.clone()) {
            vec.retain(|todo| todo.id != Some(id.to_owned()));
            return Ok(Status::NoContent);
        }
    }

    let error_response = GenericResponse {
        status: "fail".to_string(),
        message: format!("Todo with ID: {} not found", id),
    };
    Err(Custom(Status::NotFound, Json(error_response)))
}

You can now start the application with the following command

cargo run

And test the API accessing the following url: http://localhost:8000/api/todos?page=1&limit=10

You can also use the following json file to test with Postman

Make sure to check the original article which has more detailed information on the this setup

Now we just need some React FrontEnd Application to interact with this service.

Create FrontEnd Application

Now similar to my previous post related with Strapi lets create a frontend application with react.

On a different folder run the following command (Require bun.sh )

bunx create-react-app todo-frontend

Next create the following two files for the environment variables:

• .env.development

REACT_APP_BACKEND=http://localhost:1337/

• .env.production

REACT_APP_BACKEND=/

You can run the frontend application with the following command

bun run start

I’m not an expert in Frontend development and I did manage to get the create operation working, but the listing however didn’t populate although I could see on the console the data was refreshed and as the article is already long, I decided to stop here.

If you manage to get the react component working let me know so that I can update the article.

Cargo Watch

In Rust we have a library called cargo-watch which watches the source code for changes
and hot-reloads the server when required files change. Lets install it

cargo install cargo-watch

With that out of the way, run this command to start the Rocket HTTP server and restart the server when any file in the src directory changes.

cargo watch -q -c -w src/ -x run

Conclusion

Rust is gaining quite a lot popularity, implementing APIs with Rocket seems fast. This mix of React and Rust in the near future should be mixture that you would will see more.

The performance os Rust allied to the flexibility from the frontend component is something that I need to explore more.

References

• https://rocket.rs/
• https://rocket.rs/v0.5/guide/getting-started/
• https://codevoweb.com/build-a-simple-api-with-rust-and-rocket/
• https://doc.rust-lang.org/std/sync/struct.Arc.html
• https://doc.rust-lang.org/std/sync/struct.Mutex.html
• https://www.freecodecamp.org/news/how-to-consume-rest-apis-in-react/