Post a File

This is a simple example in javascript. It shows saving and fetching an image on Arweave using Liteseed API.

Save an Image

For this example we’ll use the image below and save it on Arweave.

Installing the required packages

This tutorial requires some packages to make uploading data easier.

npm install arweave

Send the Request

Uploading a file is simple send a POST Request to /data endpoint. The expected body is a FormData which expects a key "file".

import {readFileSync} from "fs";
import Arweave from "arweave";

/**
 * @param {number} size
 * @param {any} jwk
 * @param {Arweave} arweave
 */
async function sendPaymentTransaction(size, jwk, arweave) {
    const response = await fetch(`https://api.liteseed.xyz/price/${size}`);
    const {price, address} = await response.json();
    console.log("Price in AR", price); // Price of upload
    console.log("Address to pay", address); // The wallet to pay
    const tx = await arweave.createTransaction({quantity: price, target: address}, jwk);
    await arweave.transactions.sign(tx, jwk);
    await arweave.transactions.post(tx);
    console.log("Transaction Id", tx.id);
    return tx;
}

/**
 * @param file {File}
 * @param size {number}
 * @returns {Promise<{id: string; owner: string; dataCaches: string[]; fastFinalityIndexes: string[]; version: string; deadlineHeight: number;}>}
 */
async function postData(file, size) {
    const body = new FormData();
    body.append("file", file);
    body.append("tags[]", "image");
    body.append("tags[]", "image/jpeg");
    const response = await fetch(`https://api.liteseed.xyz/data`, {
        method: "POST",
        body,
        headers: {"content-length": size.toString(), "content-type": "application/octet-stream"}
    });
    const receipt = await response.json();
    console.log("Receipt", receipt);
    return receipt;
}

/**
 *
 * @param id {string}
 * @param paymentId {string}
 * @returns {Promise<any>}
 */
async function updatePaymentId(id, paymentId) {
    const response = await fetch(`https://api.liteseed.xyz/tx/${id}/${paymentId}`, {method: "PUT"});
    const payment = await response.json();
    console.log("Payment", payment);
}

async function uploadFile() {
    const file = readFileSync("file.jpeg"); // The file to upload
    const jwk = JSON.parse(readFileSync("./keyfile.json").toString());
    const arweave = Arweave.init({
        host: "arweave.net",
        protocol: "https"
    });

    const size = file.size;
    const receipt = await postData(file, size);
    const tx = await sendPaymentTransaction(size, jwk, arweave);
    await updatePaymentId(receipt.id, tx.id);
}

uploadFile().then(() => console.log("success"));