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MediaLit

Express

There are two ways to get files into MediaLit from an Express app:

  • Your server uploads. The browser sends the file to your server, which passes it on to MediaLit. This is simplest for small files and for files your server creates.

  • The browser uploads. Your server hands out a short-lived signature and the browser sends the file straight to MediaLit. Large files don't pass through your server, and dropped connections resume.

A runnable app is in examples/express.

Set up

npm
npm install express multer medialit
.env
MEDIALIT_API_KEY=your_api_key
# Only if you self-host MediaLit
# MEDIALIT_ENDPOINT=https://medialit.example.com
server.js
import express from "express";
import multer from "multer";
import { unlink } from "node:fs/promises";
import { MediaLit } from "medialit";

const app = express();
app.use(express.json());

const medialit = new MediaLit(); // reads MEDIALIT_API_KEY
const upload = multer({ dest: "uploads/" });

Upload from your server

server.js
app.post("/photos", upload.single("file"), async (req, res) => {
    if (!req.file) return res.status(400).json({ error: "file is required" });

    try {
        const media = await medialit.upload(req.file.path, {
            fileName: req.file.originalname,
            mimeType: req.file.mimetype,
            access: "public",
        });
        // Your server decided to keep the file, so seal it right away.
        const sealed = await medialit.seal(media.mediaId);
        // Save sealed.mediaId and sealed.file in your database.
        res.json(sealed);
    } catch (err) {
        res.status(500).json({ error: err.message });
    } finally {
        await unlink(req.file.path).catch(() => {});
    }
});

Try it:

curl -F "file=@photo.jpg" http://localhost:4000/photos

Let browsers upload

Add a route that gives signed-in users an upload signature:

server.js
app.post("/api/medialit/signature", requireUser, async (req, res) => {
    try {
        const signature = await medialit.getSignature({
            group: req.user.id, // optional
        });
        res.json({ signature, endpoint: medialit.endpoint });
    } catch (err) {
        res.status(500).json({ error: err.message });
    }
});

requireUser stands for your app's authentication middleware. Anyone who can call this route can upload to your MediaLit app.

In the browser, use @medialit/react or @medialit/uploader with signatureEndpoint: "/api/medialit/signature". When the user saves, send the mediaId to your server and seal it:

server.js
app.post("/profile/avatar", requireUser, async (req, res) => {
    const media = await medialit.seal(req.body.mediaId);
    // Save media.mediaId and media.file with the user's profile.
    res.json(media);
});

Files that are never sealed are deleted after 24 hours. See sealing.

List, get and delete

server.js
app.get("/photos", async (req, res) => {
    const page = Number(req.query.page ?? 1);
    res.json(await medialit.list(page, 20, { access: "public" }));
});

app.get("/photos/:id", async (req, res) => {
    // Private files get a fresh signed URL each time.
    res.json(await medialit.get(req.params.id));
});

app.delete("/photos/:id", async (req, res) => {
    await medialit.delete(req.params.id);
    res.status(204).end();
});

app.listen(4000);

Run the server with node --env-file=.env server.js. See the Node.js SDK for every method.