astrea-macro 0.2.0

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What Is Astrea?

Astrea turns your file structure into API routes — at compile time, with zero runtime cost. Drop a .rs file into the src/routes/ folder, and it becomes an HTTP endpoint. No manual route registration, no build.rs, no boilerplate.

Every handler looks the same:

#[route]
async fn handler(event: Event) -> Result<Response> {
    // your logic here
}

That's it. No complex extractor signatures. No learning curve for each parameter type.

Features

• 📁 File-based routing — file name = route path, generated at compile time
• 🎯 Unified handler signature — every handler is async fn(Event) -> Result<Response>
• 🔧 Simple extractors — get_param(), get_query_param(), get_body() — just call a function
• 🧅 Scoped middleware — _middleware.rs files with inherit (extend) or replace (override) modes
• 📝 OpenAPI auto-gen — optional Swagger UI + OpenAPI 3.0 spec from your code (feature flag openapi)
• 🔄 Axum compatible — works with all existing Axum middleware and the Tower ecosystem
• 📦 Zero extra deps — re-exports axum, tokio, serde, tower, etc. — just depend on astrea

Quick Start

1. Create a new project

cargo new my-api
cd my-api

2. Add Astrea

cargo add astrea

Or in Cargo.toml:

[package]
name = "my-api"
edition = "2024"

[dependencies]
astrea = "0.0.1"

Note: Astrea requires Rust edition 2024 (Rust ≥ 1.85).

3. Create your route files

my-api/
├── src/
│   ├── main.rs
│   └── routes/
│       ├── index.get.rs          # GET /
│       └── users/
│           ├── index.get.rs      # GET /users
│           ├── index.post.rs     # POST /users
│           └── [id].get.rs       # GET /users/:id

src/routes/index.get.rs

use astrea::prelude::*;

#[route]
pub async fn handler(event: Event) -> Result<Response> {
    json(json!({ "message": "Hello, World!" }))
}

src/routes/users/[id].get.rs

use astrea::prelude::*;

#[route]
pub async fn handler(event: Event) -> Result<Response> {
    let id = get_param_required(&event, "id")?;
    json(json!({ "user_id": id }))
}

4. Write main.rs

mod routes {
    astrea::generate_routes!();
}

#[tokio::main]
async fn main() {
    let app = routes::create_router();
    let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await.unwrap();
    println!("Listening on http://localhost:3000");
    astrea::serve(listener, app).await.unwrap();
}

5. Run

cargo run

Done. You will see a beautiful startup log:

┌─────────────────────────────────────────────────────────────────────┐
│                        🚀 Astrea Router                            │
├────────┬──────────────────────────────┬─────────────────────────────┤
│ Method │ Path                         │ Middleware                  │
├────────┼──────────────────────────────┼─────────────────────────────┤
│ GET    │ /                            │ (none)                      │
│ GET    │ /users                       │ (none)                      │
│ POST   │ /users                       │ (none)                      │
│ GET    │ /users/:id                   │ (none)                      │
└────────┴──────────────────────────────┴─────────────────────────────┘
✅ 4 route(s), 0 middleware scope(s) loaded

And GET http://localhost:3000/ returns {"message":"Hello, World!"}.

---

Route File Naming Convention

File name	Route
src/routes/index.get.rs	GET /
src/routes/users.get.rs	GET /users
src/routes/users/index.post.rs	POST /users
src/routes/users/[id].get.rs	GET /users/:id
src/routes/users/[id].delete.rs	DELETE /users/:id
src/routes/posts/[...slug].get.rs	GET /posts/*slug (catch-all)

Rules:

• File name format: <name>.<method>.rs
• index is a special name — it maps to the directory itself (no extra path segment)
• [param] → dynamic path parameter
• [...param] → catch-all parameter (matches everything after)

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Extracting Request Data

Astrea replaces complex Axum extractor signatures with simple function calls:

#[route]
pub async fn handler(event: Event, bytes: Bytes) -> Result<Response> {
    // Path parameters: /users/:id
    let id = get_param(&event, "id");                   // Option<&str>
    let id = get_param_required(&event, "id")?;          // &str (or 400 error)

    // Query parameters: /search?q=rust&page=2
    let q = get_query_param(&event, "q");                // Option<String>
    let all_query = get_query(&event);                   // &HashMap<String, String>

    // Request body (JSON)
    let body: MyStruct = get_body(&event, &bytes)?;      // deserialized struct

    // Headers
    let auth = get_header(&event, "authorization");      // Option<String>

    // Metadata
    let method = get_method(&event);                     // &Method
    let path = get_path(&event);                         // &str

    // Application state
    let db = get_state::<DatabasePool>(&event)?;         // your custom state

    json(json!({ "ok": true }))
}

---

Response Helpers

// JSON (application/json)
json(json!({ "key": "value" }))?

// Plain text (text/plain)
text("Hello!")

// HTML (text/html)
html("<h1>Hello</h1>")

// Redirect (302 Found)
redirect("/login")?

// No Content (204)
no_content()

// Raw bytes
bytes(vec![0x89, 0x50, 0x4E, 0x47]).content_type("image/png")

// Streaming
stream(Body::from_stream(my_stream))

All responses support chaining:

json(data)?
    .status(StatusCode::CREATED)
    .header("X-Request-Id", "abc123")

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Error Handling

Return errors naturally — they become proper HTTP responses automatically:

#[route]
pub async fn handler(event: Event) -> Result<Response> {
    let id = get_param_required(&event, "id")?;       // 400 if missing

    if id == "0" {
        return Err(RouteError::not_found("User not found"));  // 404
    }

    // Third-party errors auto-convert to 500 via anyhow
    let data = some_fallible_operation()?;

    json(data)
}

Built-in error variants:

Method	Status Code
RouteError::bad_request(msg)	400
RouteError::unauthorized(msg)	401
RouteError::forbidden(msg)	403
RouteError::not_found(msg)	404
RouteError::conflict(msg)	409
RouteError::validation(msg)	422
RouteError::rate_limit(msg)	429
RouteError::custom(StatusCode, msg)	any
? on any anyhow-compatible error	500

All errors are returned as JSON: {"error": "...", "status": 404}.

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Middleware

Create _middleware.rs files anywhere in the src/routes/ directory. They scope to the folder they live in + all subfolders.

src/routes/
├── _middleware.rs            # applies to ALL routes
├── api/
│   ├── _middleware.rs        # applies to /api/* (stacks on root)
│   ├── users.get.rs          # ← root + api middleware
│   └── public/
│       ├── _middleware.rs    # OVERRIDES parent middleware
│       └── health.get.rs    # ← public middleware only

Extend mode (default) — stack on parent

// src/routes/_middleware.rs
use astrea::middleware::*;

pub fn middleware() -> Middleware {
    Middleware::new()
        .wrap(|router| {
            router
                .layer(tower_http::trace::TraceLayer::new_for_http())
                .layer(tower_http::cors::CorsLayer::permissive())
        })
}

Override mode — replace parent middleware

// src/routes/api/public/_middleware.rs
use astrea::middleware::*;

pub fn middleware() -> Middleware {
    Middleware::override_parent()
        .wrap(|router| {
            router.layer(tower::limit::ConcurrencyLimitLayer::new(100))
        })
}

---

OpenAPI (Optional)

Enable the openapi feature to get automatic API documentation:

[dependencies]
astrea = { version = "0.0.1", features = ["openapi"] }

Then merge the OpenAPI router:

let app = routes::create_router()
    .merge(astrea::openapi::router("My API", "1.0.0"));

This gives you:

• GET /openapi.json — the OpenAPI 3.0 spec
• GET /swagger — Swagger UI

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Application State

Share state across handlers (database pools, config, etc.):

#[derive(Clone)]
struct AppState {
    db: DatabasePool,
}

// In handler:
#[route]
pub async fn handler(event: Event) -> Result<Response> {
    let state = get_state::<AppState>(&event)?;
    // use state.db ...
}

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Full Example

my-api/
├── Cargo.toml
└── src/
    ├── main.rs
    └── routes/
        ├── _middleware.rs
        ├── index.get.rs
        └── api/
            ├── _middleware.rs
            ├── users.get.rs
            ├── users.post.rs
            └── users/
                ├── [id].get.rs
                ├── [id].put.rs
                └── [id].delete.rs

This generates:

• GET / — root page
• GET /api/users — list users
• POST /api/users — create user
• GET /api/users/:id — get user by ID
• PUT /api/users/:id — update user
• DELETE /api/users/:id — delete user

Root middleware → all routes. API middleware → /api/* routes.

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Why Astrea?

	Astrea	Plain Axum
Route definition	Drop a file	Manual .route() calls
Handler signature	Always (Event) -> Result<Response>	Varies per extractor combo
Parameter access	get_param(&event, "id")	Path(id): Path<String>
Error handling	Built-in JSON errors	DIY
Middleware	File-based scoping	Manual nesting
OpenAPI	Auto-generated	Manual or third-party

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Minimum Supported Rust Version

Rust 1.85 or later (edition 2024).

License

MIT © TNXG (Asahi Shiori)