我不是Web开发方面的杰出专家（至少目前希望如此），所以我的问题可能有点傻。

这是我的问题： 我一直在研究Node.Js，并试图创建一个数据库，我可以在其中上传图片，然后检索它们并通过.ejs文件在浏览器中显示它们。

不幸的是，在app.js文件中，我能够console.log images数组，并检查至少一个文件的filename，同时在.ejs上循环访问这样做：

   `<% for(var i = 0; i <= images.length; i++){ %>
        <img src="<%= images[i].filename %>">
    <% } %>`

我收到此问题标题中所示的错误。

有人知道我在做什么错吗？我相信我使用GridFS或multer设置了错误，但是我不确定100％。

在此先感谢您打算答复的人。

现在您可以在app.js文件中找到我正在使用的代码：

var express                         = require('express'),mongoose                        = require('mongoose'),bodyParser                      = require('body-parser'),methodOverride                  = require('method-override'),expressSanitizer                = require('express-sanitizer'),path                            = require('path'),crypto                          = require('crypto'),multer                          = require('multer'),GridFsStorage                   = require('multer-gridfs-storage'),Grid                            = require('gridfs-stream'),app                             = express();

//connect to the MongoDB database
mongoose.connect("mongodb+srv://***:*****@cluster-***-***-q5eof.mongodb.net/*****?retryWrites=true&w=majority",{ useNewUrlParser: true,useUnifiedTopology: true,useFindAndmodify: false,useCreateIndex: true});

//connect to the MongoDB database
var mongoURI = "mongodb+srv://***:*****@cluster-***-***-q5eof.mongodb.net/*****?retryWrites=true&w=majority";

var conn = mongoose.createConnection(mongoURI)

//parseing incoming request bodies in a middleware before the handlers,available under the req.body property
app.use(bodyParser.urlencoded({extended: true}));

//setting the engine to read directly the ejs files without specifying their extentions on the routes
app.set('view engine','ejs');

//serving images,CSS files,and JavaScript files in a directory named public:
app.use(express.static('public'));

//setting method-override to be used via '_method' text before specifying the type of method used in a form
app.use(methodOverride('_method'));

//execute express-sanitizer
app.use(expressSanitizer());

let gfs
conn.once('open',() => {
  gfs = Grid(conn.db,mongoose.mongo)
  gfs.collection('uploads')
  console.log('GRID CONNECTION SUCCESSFUL')
})

//Landing page
app.get('/',function(req,res){
    gfs.files.find().toArray(function(err,images){
        if(err){
            console.log(err)
        } else {
                images.map(function(image){
                image.isImage = true;
            });
        }
        res.render('landing',{images: images});
        console.log(images[0].filename);
    });
});

//Create storage engine
 var storage = new GridFsStorage({
  url: mongoURI,file: (req,file) => {
    return new Promise((resolve,reject) => {
      crypto.randomBytes(16,(err,buf) => {
        if (err) {
          return reject(err);
        }
        const filename = buf.toString('hex') + path.extname(file.originalname);
        const fileInfo = {
          filename: filename,bucketName: 'uploads'
        };
        resolve(fileInfo);
      });
    });
  }
});
const upload = multer({ storage });

//Upload page
app.get('/upload',res){
    res.render('upload');
});

//Sending form from upload page
app.post('/upload',upload.array('file'),res){
    res.json({file: req.files});
});

app.listen('3000',function(err){
    if(err){
        console.log(err)
    } else{
        console.log("APP CONNECTED")
    }
});