rust-workshop => backend-rust

backend-rust/step1-json-api/src/api.rs

@@ -0,0 +1,30 @@
+use crate::errors::{err_msg, Error};
+use serde::{Deserialize, Serialize};
+use serde_json::value::RawValue;
+
+pub type AppResult<T> = ::std::result::Result<T, Box<Error>>;
+
+#[derive(Deserialize)]
+#[serde(tag = "action")]
+pub enum Request {
+    Post { message: String, username: String },
+    Fetch { username: Option<String> },
+}
+
+#[derive(Serialize, Debug)]
+#[serde(untagged)]
+pub enum Response {
+    Post { count: i32 },
+    Fetch { posts: Box<RawValue> },
+    Error { error: String },
+}
+
+pub fn parse(s: String) -> AppResult<Request> {
+    serde_json::from_str(s.as_str())
+        .map_err(|e| err_msg(&format!("unable to parse json request from {}: {}", s, e)))
+}
+
+pub fn serialize(response: &Response) -> String {
+    serde_json::to_string(response)
+        .unwrap_or(format!("Unable to serialize response {:?}", response))
+}

backend-rust/step1-json-api/src/errors.rs

@@ -0,0 +1,16 @@
+use std::fmt;
+
+#[derive(Debug)]
+pub struct Error(String);
+
+impl std::error::Error for Error {}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+pub fn err_msg(s: &str) -> Box<Error> {
+    Error(s.to_string()).into()
+}

backend-rust/step1-json-api/src/lib.rs

@@ -0,0 +1,60 @@
+use fluence::sdk::*;
+use serde_json::value::RawValue;
+
+use api::Request;
+use api::Response;
+
+use crate::api::AppResult;
+use crate::errors::err_msg;
+
+pub mod api;
+pub mod errors;
+pub mod model;
+
+fn init() {
+    logger::WasmLogger::init_with_level(log::Level::Info).unwrap();
+    model::create_scheme().unwrap();
+}
+
+#[invocation_handler(init_fn = init)]
+fn run(arg: String) -> String {
+    // Parse and username JSON request
+    let result = api::parse(arg).and_then(|request| match request {
+        Request::Post { message, username } => add_post(message, username),
+        Request::Fetch { username } => fetch_posts(username),
+    });
+
+    let result = match result {
+        Ok(good) => good,
+        Err(error) => Response::Error {
+            error: error.to_string(),
+        },
+    };
+
+    // Serialize response to JSON
+    api::serialize(&result)
+}
+
+fn add_post(msg: String, username: String) -> AppResult<Response> {
+    // Store post
+    model::add_post(msg, username)?;
+    // Get total number of posts
+    let count = model::get_posts_count()?;
+
+    Ok(Response::Post { count })
+}
+
+fn fetch_posts(username: Option<String>) -> AppResult<Response> {
+    let posts_str = match username {
+        // Get all posts if no filter username was passed
+        None => model::get_all_posts()?,
+        // Or get only posts from specified author
+        Some(h) => model::get_posts_by_username(h)?,
+    };
+
+    // Some Rust-specific detail to play nice with serialization, doesn't matter
+    let raw = RawValue::from_string(posts_str)
+        .map_err(|e| err_msg(&format!("Can't create RawValue: {}", e)))?;
+
+    Ok(Response::Fetch { posts: raw })
+}

backend-rust/step1-json-api/src/model.rs

@@ -0,0 +1,25 @@
+use crate::api::AppResult;
+use log;
+
+pub fn create_scheme() -> AppResult<()> {
+    Ok(log::info!("creating scheme"))
+}
+
+pub fn add_post(msg: String, username: String) -> AppResult<()> {
+    Ok(log::info!("add post {} {}", msg, username))
+}
+
+pub fn get_all_posts() -> AppResult<String> {
+    log::info!("get all posts");
+    Ok("[]".to_string())
+}
+
+pub fn get_posts_by_username(username: String) -> AppResult<String> {
+    log::info!("get all posts by username {}", username);
+    Ok("[]".to_string())
+}
+
+pub fn get_posts_count() -> AppResult<i32> {
+    log::info!("get posts count");
+    Ok(0)
+}