如何解决 JavaScript 中的这个"纳米"错误？

Question

/home/admin/.pm2/logs/app-error.log最后15行：3|app|at对象(/home/admin/pcpro backend/helper/db.helper.js:1:29(3|app|
模块_compile(internal/modules/cjs/loader.js:1085:14(3|app
|at Object。模块_扩展。。js(internal/modules/cjs/loader.js:1114:10(3|app|atModule.load(internal/modules/cjs/loader.js:950:32(3|app|
函数。模块_load(internal/modules/cjs/loader.js:790:12(3|app|在Module.require(internal/modules/cjs/loader.js:974:19(3|app|在模块中。钩子_要求模块.request(/usr/local/lib/node_modules/pm2/node_modules/request在中间/index.js:80:39(3|app|at required(internal/modules/cjs/helpers.js:101:18(对象处的3|app|。(/home/admin/pcpro backend/routes/users.js:4:18(｛3|app|
generatedMessage:false，3|app|代码：'ERR_ASSERTION'，3|app
|实际：'undefined'，3| app|预期：'object'，3|1pp
|operator:'strictEqual'3|app||｝

app.js

var fs = require("fs");
const dotenv = require('dotenv');


var express = require('express');
var path = require('path');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var methodOverride = require('method-override');
var cors = require('cors');

var index = require('./routes/index');
var users = require('./routes/users');
var languages = require('./routes/language');
var formAndTemplates = require('./routes/formAndTemplates');
var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({'extended':'true'}));
app.use(bodyParser.json({type:'application/vnd.api+json'}));
app.use(methodOverride());
app.use(cookieParser());
app.use(cors());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/uploads', express.static(path.join(__dirname, 'uploads')));

app.use('/', index);
app.use('/users', users);
app.use('/languages', languages);
app.use('/api/v1/form-template', formAndTemplates);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});

// error handler
app.use(function(err, req, res, next) {
// set locals, only providing error in development
res.locals.message = err.message;
res.locals.error = req.app.get('env') === 'development' ? err : {};

// render the error page
res.status(err.status || 500);
res.json(err.message);
});

module.exports = app;

.env

COUCHDB_URL=http://admin:somepassword@localhost:5984/
PORT=3002
NODE_ENV=local

db.helper

const nano = require('nano')(process.env.COUCHDB_URL);

const getDBInstance = (name) => {
return nano.db.use(name)
};

module.exports = {
getDBInstance
};

如何解决此错误？

Answer 1

nano.db.use与所有nano方法非常相似，是异步的。现代的实现使用异步/等待模式，尽管有些人继续使用Promises。

试试这样的东西作为健全性检查：

const nano = require("nano")("http://user:pass@localhost:5984/");
const getDBInstance = async (name) => nano.db.use(name);
(async () => {
let db = await getDBInstance("stack");
let result = await db.info();
console.log(JSON.stringify(result, 0, 2));
})();