rust 53 lines · 7 steps

Handling raw byte uploads in Axum

An Axum route accepts a raw request body, enforces a size cap, persists it, and returns a typed JSON receipt.

Explained by highlit
Axum Intermediate extractors shared-state request-limits error-handling json-responses
1use axum::{
2 body::Bytes,
3 extract::State,
4 http::StatusCode,
5 response::IntoResponse,
6 routing::post,
7 Json, Router,
8};
9use serde::Serialize;
10use tower_http::limit::RequestBodyLimitLayer;
11 
12#[derive(Clone)]
13struct AppState {
14 store: std::sync::Arc<UploadStore>,
15}
16 
17#[derive(Serialize)]
18struct UploadReceipt {
19 id: String,
20 size: usize,
21}
22 
23const MAX_UPLOAD_BYTES: usize = 2 * 1024 * 1024;
24 
25async fn upload_document(
26 State(state): State<AppState>,
27 body: Bytes,
28) -> Result<(StatusCode, Json<UploadReceipt>), StatusCode> {
29 if body.is_empty() {
30 return Err(StatusCode::BAD_REQUEST);
31 }
32 
33 let id = state
34 .store
35 .persist(&body)
36 .await
37 .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
38 
39 Ok((
40 StatusCode::CREATED,
41 Json(UploadReceipt {
42 id,
43 size: body.len(),
44 }),
45 ))
46}
47 
48pub fn documents_router(state: AppState) -> Router {
49 Router::new()
50 .route("/documents", post(upload_document))
51 .layer(RequestBodyLimitLayer::new(MAX_UPLOAD_BYTES))
52 .with_state(state)
53}
01 / 01
STEP 01

Walkthrough

Space play ←→ step click any line
Three takeaways
  1. 1Axum extractors like State and Bytes turn request parsing into typed function arguments.
  2. 2Returning Result<T, StatusCode> lets a handler map failures to HTTP status codes ergonomically.
  3. 3Body-size limits belong in a middleware layer, not scattered through handler logic.

Related explainers

rust 
use std::time::Duration;
 
use axum::{
    http::{header, HeaderValue, Method},

Configuring CORS on an Axum Router

cors middleware http-headers
Intermediate 7 steps
javascript 
const RETRIABLE_STATUS = new Set([408, 429, 500, 502, 503, 504]);
 
function sleep(ms, signal) {
  return new Promise((resolve, reject) => {

Retrying fetch with exponential backoff

retry exponential-backoff abort-signal
Advanced 8 steps
rust 
use axum::{
    extract::{Query, State},
    http::StatusCode,
    Json,

Paginated, filtered product listing in Axum

pagination query-parameters sql-filtering
Intermediate 8 steps
php 
<?php
 
namespace App\Support;
 

Retry with exponential backoff in PHP

retry exponential-backoff error-handling
Intermediate 7 steps
typescript 
import { inject } from '@angular/core';
import { ResolveFn, Router, ActivatedRouteSnapshot } from '@angular/router';
import { catchError, of, EMPTY } from 'rxjs';
import { Article } from './models/article';

Prefetching route data with an Angular resolver

route-resolver dependency-injection rxjs
Intermediate 6 steps
python 
from itertools import islice
from typing import Iterable, Iterator, TypeVar
 
T = TypeVar("T")

Batching an iterable for bulk indexing

generators batching lazy-evaluation
Intermediate 7 steps

Share this explainer

Here's the card — post it anywhere.

Handling raw byte uploads in Axum — share card
Made with highlit — turn any snippet into a walkthrough like this in about a minute.
Explain your code