DApp設計與開發 課程筆記（六）：NFT交易市場後端開發

孤飞發表於2024-07-02
APP筆記後端

筆記對應課程內容為成都資訊工程大學區塊鏈產業學院老師梁培利的DApp 設計與開發 17-18 課

筆記中提到的名詞不做過多解釋 不懂就搜！

tokenuri 對應一個metadata的 json 資料

上傳一個圖片，將圖片上傳到IPFS，獲得一個cid，然後將json格式的metadata上傳到IPFS，然後給使用者傳送一個NFT

程式碼：https://github.com/liangpeili/nft-market-backend

app.js

import express from 'express';
import cors from 'cors';
import bodyParser from 'body-parser';
import fileUpload from 'express-fileupload';
import { addFileToIPFS, addJSONToIPFS } from './ipfs-uploader.js';
import { mint } from './nft-minter.js';
import dotenv from 'dotenv';
dotenv.config("./.env");

const app = express()

app.set('view engine','ejs')
app.use(bodyParser.urlencoded({extended:true}))
app.use(fileUpload())
app.use(cors())

app.get('/', (req,res) => {
    res.render('home')
})

app.post('/upload', (req, res) => {
    if (!req.files || Object.keys(req.files).length === 0) {
        return res.status(400).json({ message: 'No files were uploaded.' });
    }

    const file = req.files.file;
    const fileName = file.name
    const filePath = 'files/' + fileName

    const title = req.body.title
    const description = req.body.description
    const address = req.body.address

    console.log(title, description, address)

    file.mv(filePath, async (err) => {
        if (err) {
            console.log('error: failed to download the file.')
            return res.status(500).send(err)
        }

        const fileResult = await addFileToIPFS(filePath)
        console.log('File added to IPFS:', fileResult.cid.toString());

        const metadata = {
            title,
            description,
            image: 'http://127.0.0.1:8080/ipfs/' + fileResult.cid.toString() + '/' + fileName
        }
        const jsonResult = await addJSONToIPFS(metadata)
        console.log('Metadata added to IPFS:', jsonResult.cid.toString());

        const userAddress = address || process.env.ADDRESS;
        await mint(userAddress, 'http://127.0.0.1:8080/ipfs/' + jsonResult.cid.toString())

        res.json({ 
            message: 'File uploaded successfully.', 
            metadata
        });
    });
});

const HOST = process.env.HOST 
const PORT = process.env.PORT

app.listen(PORT, HOST, () => {
    console.log(`Server is running on port ${PORT}`)
})

ipfs-uploader.js

import { create } from 'kubo-rpc-client';
import fs from 'fs';
import dotenv from 'dotenv';
dotenv.config("./.env");

const ipfs = create(new URL(process.env.IPFS_URL))

export async function addJSONToIPFS(json) {
  try {
      const result = await ipfs.add(JSON.stringify(json));
      return result;
  } catch (error) {
      console.error('Failed to add JSON to IPFS:', error);
  }
}

export async function addFileToIPFS(filePath) {
  try {
      const file = fs.readFileSync(filePath);
      const result = await ipfs.add({ path: filePath, content: file });
      return result;
  } catch (error) {
      console.error('Failed to add file to IPFS:', error);
  }
}

nft-minter.js

import { ethers, JsonRpcProvider } from "ethers";
import fs from 'fs';
import dotenv from 'dotenv';
dotenv.config("./.env");

export async function mint(address, uri) {
    const provider = new JsonRpcProvider(process.env.RPC);
    const signer = await provider.getSigner()

    const MyNFTAbi = JSON.parse(fs.readFileSync('./abis/MyNFT.json'));
    const MyNFTContract = new ethers.Contract(process.env.NFT, MyNFTAbi, signer);

    const result = await MyNFTContract.safeMint(address, uri);
    console.log(result.hash);
}

// mint('0x70997970C51812dc3A010C7d01b50e0d17dc79C8', 'https://ipfs.io/ipfs/QmZ4tj')

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