Node.JS IPFS 發送消息 TypeError: Cannot read properties of undefined (reading 'publish')

Question

我正在嘗試通過 IPFS.network 發送消息，但我不斷收到錯誤TypeError: Cannot read properties of undefined (reading 'publish') 。

錯誤發生在node.pubsub.publish(topic, msg, (err) => {})行。

ipfs.js是應用程序的主要引擎，包含與 IPFS.network 交互所需的方法。

'sendNewMsg' 方法用於將消息發送到主題，其他節點可以在該主題中訂閱和閱讀消息。

index.js調用並執行該方法。

你能幫我發現並解決問題嗎？

提前致謝！

ipfs.js:

const IPFS = require('ipfs');
const BufferPackage = require('buffer');

const Buffer = BufferPackage.Buffer;

class IPFSEngine {

    constructor(){
        let node = IPFS.create({
            EXPERIMENTAL: { pubsub: true },
            repo: (() => `repo-${Math.random()}`)(),
            config: {
                Addresses: {
                    Swarm: [
                        '/dns4/ws-star.discovery.libp2p.io/tcp/443/wss/p2p-websocket-star'
                    ]
                }
            }
        });

        this.node = node;
    }

    ....
    ....
    ....

    sendNewMsg(topic, newMsg) {
        let {node} = this;
        console.log('Message sent: ', newMsg)
        const msg = Buffer.from(newMsg)
        node.pubsub.publish(topic, msg, (err) => {
            if (err) {
                return console.error(`Failed to publish to ${topic}`, err)
            }
            // msg was broadcasted
            console.log(`Published to ${topic}`)
        })
    }
}

// Export IPFSEngine
module.exports = {IPFSEngine};

索引.js：

const {IPFSEngine} = require('./ipfs');

const ipfs = new IPFSEngine();

ipfs.sendNewMsg(`topic2`,`Messages 2 ..!`)

Answer 1

當您嘗試訪問 object 上的publish屬性時，錯誤指出node.pubsub未定義。

快速閱讀IPFS 文檔中的一個示例， IPFS.create似乎是一個異步的 API，結果您沒有等待。 它可以解釋為什么您在節點上獲得未定義的pubsub屬性。

使用異步 function，你可以這樣寫：

async function sendNewMsg(topic, newMsg) {
  let { node } = this;
  console.log('Message sent: ', newMsg);
  const msg = Buffer.from(newMsg);
  (await node).pubsub.publish(topic, msg, (err) => {
    if (err) {
      return console.error(`Failed to publish to ${topic}`, err);
    }
    // msg was broadcasted
    console.log(`Published to ${topic}`);
  });
}

或者沒有 async/await 語法：

function sendNewMsg2(topic, newMsg) {
  let { node } = this;
  console.log('Message sent: ', newMsg);
  const msg = Buffer.from(newMsg);
  node.then((readyNode) => {
    readyNode.pubsub.publish(topic, msg, (err) => {
      if (err) {
        return console.error(`Failed to publish to ${topic}`, err);
      }
      // msg was broadcasted
      console.log(`Published to ${topic}`);
    });
  })
}