Express.js TypeError：无法读取未定义的属性（读取“名称”）

Question

我正在尝试设置一个快速服务器，该服务器之前已经可以运行。但是当我在文件上编写一些功能时，由于指定的属性，它开始崩溃。

文件（index.js）：

fs = require('fs')
const path = require('path')
const Sequelize = require ('sequelize')
const config = require('../config/config')
const db = {}
/* const sequelize = require('../databaseConfig');
const { DataTypes } = require('sequelize'); */

/* INICIANDO A INSTÂNCIA DB DO SEQUELIZE */
const sequelize = new Sequelize(
    config.db.database,
    config.db.user,
    config.db.password,
    config.db.options
)
/************* */

fs
    .readdirSync(__dirname) //ler um diretório e passar um array com diferentes arquivos. 
    .filter((file) =>
        file !== 'index.js'
    ) //filtrar cada arquivo que seja equivalente ao "index.js" (não queremos o arquivo "index.js", mas queremos todos os outros arquivos de "models").
    
    /* PARA CADA ARQUIVO QUE FOR ENCONTRADO... */
    .forEach((file) => {
        // VVVV será declarado um modelo que armazenará seu caminho relativo para ser usado com o sequelize.
        const model = require(path.join(__dirname, file))(sequelize, Sequelize.DataTypes)
        //VVVV setar o nome do db como descrito abaixo.
        db[model.name] = model
    })
    /******* */  

db.sequelize = sequelize //acesso ao objeto sequelize.
db.Sequelize = SequeLize //acesso ao objeto CamelCase do SequeLize. 

module.exports = db

错误代码（node.js）：

C:\Users\pedro\OneDrive\Documentos\GitHub\autiapp-tcc-pedro\servidor\models\index.js:29
        db[model.name] = model
                 ^

TypeError: Cannot read properties of undefined (reading 'name')
    at C:\Users\pedro\OneDrive\Documentos\GitHub\autiapp-tcc-pedro\servidor\models\index.js:29:18
    at Array.forEach (<anonymous>)
    at Object.<anonymous> (C:\Users\pedro\OneDrive\Documentos\GitHub\autiapp-tcc-pedro\servidor\models\index.js:25:6)   
    at Module._compile (node:internal/modules/cjs/loader:1105:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1159:10)
    at Module.load (node:internal/modules/cjs/loader:981:32)
    at Function.Module._load (node:internal/modules/cjs/loader:822:12)
    at Module.require (node:internal/modules/cjs/loader:1005:19)
    at require (node:internal/modules/cjs/helpers:102:18)   
    at Object.<anonymous> (C:\Users\pedro\OneDrive\Documentos\GitHub\autiapp-tcc-pedro\servidor\app.js:5:21)
[nodemon] app crashed - waiting for file changes before starting...

有人可以帮助我吗？谢谢！

我尝试在函数之前导入变量，但它也不起作用。

Answer 1

此处的解决方案取决于您目录中的文件。我不知道这些文件是什么，所以我能给你的最好答案是帮助你调试代码。

TypeError: Cannot read properties of undefined (reading ...)

是javascript中的一个常见错误。这意味着您正在尝试访问对象的属性，但该对象是

undefined

。在你的情况下，

model

是

undefined

。如果您在带有

console.log('This is my model ---', model)

的行之前添加

db[model.name] = model

语句，您就会明白我的意思。文件数组中的第一个文件可能会发生这种情况。最后一个文件可能会发生这种情况。要了解哪些文件导致此问题，您还应该

console.log

file

变量。这将帮助您查明确切的问题。