DApp设计与开发 课程笔记（六）：NFT交易市场后端开发

笔记对应课程内容为成都信息工程大学区块链产业学院老师梁培利的DApp 设计与开发 17-18 课

笔记中提到的名词不做过多解释 不懂就搜！

tokenuri 对应一个metadata的 json 数据

上传一个图片，将图片上传到IPFS，获得一个cid，然后将json格式的metadata上传到IPFS，然后给用户发送一个NFT

代码：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')