coder-rust-axum-api

<skill_overview> <purpose>Build robust, typed, and maintainable HTTP APIs with axum</purpose> <triggers> <trigger>Creating new axum endpoints</trigger> <trigger>Designing routers and route groups</trigger> <trigger>Using extractors for request data</trigger> <trigger>Sharing application state safely</trigger> <trigger>Implementing middleware and error mapping</trigger> </triggers> <sources> <source url="https://github.com/tokio-rs/axum">Axum GitHub</source> <source url="https://github.com/tokio-rs/axum/blob/main/axum/src/docs/extract.md">Axum Extractors Docs</source> </sources> </skill_overview> <routing> <rules> <rule>Use Router::route with method routers for clarity</rule> <rule>Group related endpoints with nested routers</rule> <rule>Prefer typed Path and Query extractors over manual parsing</rule> <rule>Use fallback to handle unknown routes consistently</rule> </rules> <example> <code> use axum::{routing::{get, post}, Router};

let app = Router::new() .route("/users", get(list_users).post(create_user)) .route("/users/{id}", get(get_user)); </code> </example> </routing> <extractors> <principles> <principle>Compose multiple extractors in one handler</principle> <principle>Only one body-consuming extractor per handler</principle> <principle>Validate and deserialize input via extractors, not manually</principle> </principles> <common> <item>Path for route params</item> <item>Query for query string</item> <item>Json for JSON payloads</item> <item>State for shared app state</item> </common> <example> <code> async fn handler( State(state): State<AppState>, Path(id): Path<u64>, Query(params): Query<Pagination> ) { /* ... */ } </code> </example> </extractors> <state_management> <rules> <rule>Keep AppState cloneable and cheap to clone</rule> <rule>Store shared resources behind Arc</rule> <rule>Use State for app-level dependencies</rule> </rules> <example> <code> #[derive(Clone)] struct AppState { pool: std::sync::Arc<DbPool>, } </code> </example> </state_management> <middleware> <rules> <rule>Apply Router::layer for global middleware</rule> <rule>Use route_layer for per-route middleware</rule> <rule>Prefer explicit ordering of layers</rule> </rules> <example> <code> use axum::{middleware, Router};

let app = Router::new() .route("/health", get(health)) .route_layer(middleware::from_fn(auth_middleware)); </code> </example> </middleware> <error_handling> <rules> <rule>Return Result from handlers and map errors to responses</rule> <rule>Implement IntoResponse for custom error types</rule> <rule>Never panic on expected errors</rule> </rules> <example> <code> enum AppError { NotFound, BadRequest }

impl axum::response::IntoResponse for AppError { /* map to status */ }

async fn handler() -> Result<impl axum::response::IntoResponse, AppError> { /* ... */ } </code> </example> </error_handling>