使用XMLHttpRequest将多个文件上载到Express.js 3.5 Server

Question

我正在尝试使用JavaScript中的本机FileAPI构建文件上传器,我想通过XMLHttpRequest(不带jQuery)将文件上传到使用Express.js的Node.js服务器.

文件读取部分工作正常,当我上传没有XMLHttpRequest的文件时,它工作正常(文件在Express.js 中的req.files).

问题是通过AJAX上传:req.files总是空的.

下面是一些代码:

表格:

<form action="http://localhost:3000/upload" method="POST" enctype="multipart/form-data" name="form">
  <input type="file" name="uploads" id="files" multiple="multiple">
  <input type="submit" name="submit" value="submit">
</form>

前端的上传部分(在文件[0] .data中是一个文件 - 不是数组或其他东西):

function uploadFiles(files) {
    var xhr = new XMLHttpRequest();
    xhr.submittedData = files; // Array of objects with files included. But it neither works with an array of files nor just one file
    xhr.onload = successfullyUploaded;
    xhr.open("POST", "http://localhost:3000/upload", true);
    xhr.setRequestHeader('X-Requested-With','XMLHttpRequest');
    xhr.send();
}

发生问题的后端:

exports.receiveUpload = function(req, res){
    console.log(req.files); // empty
    var files = req.files.uploads; // always empty with AJAX upload. with normal upload it's fine
    console.log(req.xhr); // true
    // ...
}

这里有一些Express.js配置(没有AJAX我已经有了同样的错误 - 在代码中的注释中你可以看到行和Stack Overflow帖子解决了上传而没有AJAX):

// all environments
app.set('port', process.env.PORT || 3000);
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');
app.use(express.favicon());
app.use(express.logger('dev'));
app.use(express.json());
app.use(express.urlencoded());

// this 3 lines have to be before app.use(app.router)
// https://stackoverflow.com/questions/21877098/upload-file-using-express-failed-cannot-read-property-of-undefined
app.use(express.multipart());
app.use(express.bodyParser({ keepExtensions: true, uploadDir: path.join(__dirname, 'public', 'uploads') }));
app.use(express.methodOverride());


app.use(app.router);
app.use(require('less-middleware')(path.join(__dirname, '/public')));
app.use(express.static(path.join(__dirname, 'public')));

提前致谢!

问候,

C.

Answer 1

感谢@Pengtuzi我解决了它:

我使用FormData API上传文件.我的错误是我认为错误会在服务器上发生.

这是为我解决的代码:

function uploadFiles(files) {
    var xhr = new XMLHttpRequest();
    var formData = new FormData();
    xhr.onload = successfullyUploaded;
    xhr.open("POST", "http://localhost:3000/upload", true);
    xhr.setRequestHeader('X-Requested-With','XMLHttpRequest');
    for(var file in files) {
        formData.append("uploads", files[file].data);
    }
    xhr.send(formData);
}