你好，我尝试了每件事，如mongoose.connect('mongodb://localhost/blog')，但我不能连接mongoose节点这里是我的代码....

const express = require('express')
const mongoose = require('mongoose')
const articleRouter = require('./routes/articles')
const app = express()

mongoose.connect('mongodb://localhost:27017/blog')

app.set('view engine','ejs')

错误如下：

/home/vishwajeet/webdeve/MARKDOWN-BLOG/node_modules/mongoose/lib/connection.js:807
  const serverSelectionError = new ServerSelectionError();
                               ^

MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017
    at NativeConnection.Connection.openUri (/home/vishwajeet/webdeve/MARKDOWN-BLOG/node_modules/mongoose/lib/connection.js:807:32)
    at /home/vishwajeet/webdeve/MARKDOWN-BLOG/node_modules/mongoose/lib/index.js:342:10
    at /home/vishwajeet/webdeve/MARKDOWN-BLOG/node_modules/mongoose/lib/helpers/promiseOrCallback.js:32:5
    at new Promise (<anonymous>)
    at promiseOrCallback (/home/vishwajeet/webdeve/MARKDOWN-BLOG/node_modules/mongoose/lib/helpers/promiseOrCallback.js:31:10)
    at Mongoose._promiseOrCallback (/home/vishwajeet/webdeve/MARKDOWN-BLOG/node_modules/mongoose/lib/index.js:1181:10)
    at Mongoose.connect (/home/vishwajeet/webdeve/MARKDOWN-BLOG/node_modules/mongoose/lib/index.js:341:20)
    at Object.<anonymous> (/home/vishwajeet/webdeve/MARKDOWN-BLOG/server.js:8:10)
    at Module._compile (node:internal/modules/cjs/loader:1103:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1157:10) {
  reason: TopologyDescription {
    type: 'Unknown',
    servers: Map(1) {
      'localhost:27017' => ServerDescription {
        _hostAddress: HostAddress { isIPv6: false, host: 'localhost', port: 27017 },
        address: 'localhost:27017',
        type: 'Unknown',
        hosts: [],
        passives: [],
        arbiters: [],
        tags: {},
        minWireVersion: 0,
        maxWireVersion: 0,
        roundTripTime: -1,
        lastUpdateTime: 774709,
        lastWriteDate: 0,
        error: MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27017
            at connectionFailureError (/home/vishwajeet/webdeve/MARKDOWN-BLOG/node_modules/mongodb/lib/cmap/connect.js:375:20)
            at Socket.<anonymous> (/home/vishwajeet/webdeve/MARKDOWN-BLOG/node_modules/mongodb/lib/cmap/connect.js:295:22)
            at Object.onceWrapper (node:events:646:26)
            at Socket.emit (node:events:526:28)
            at emitErrorNT (node:internal/streams/destroy:157:8)
            at emitErrorCloseNT (node:internal/streams/destroy:122:3)
            at processTicksAndRejections (node:internal/process/task_queues:83:21) {
          [Symbol(errorLabels)]: Set(0) {}
        }
      }
    },
    stale: false,
    compatible: true,
    heartbeatFrequencyMS: 10000,
    localThresholdMS: 15,
    logicalSessionTimeoutMinutes: undefined
  },
  code: undefined
}