javascript - 无法返回node.js中的变量

Question

我从函数中返回变量 uploadFile，当我尝试在另一个变量中访问它时，它给了我未定义

function upload(req, res, callback) {
    var dir = 'uploads/';

    if (!fs.existsSync(dir)) {
        fs.mkdirSync(dir);
    }

    console.log(req.files.file1);
    console.log(req.files.file2);

    var uploadFiles = {
        ext1: path.extname(req.files.file1.originalname),
        path1: req.files.file1.path,
        ext2: path.extname(req.files.file2.originalname),
        path2: req.files.file2.path
    }
    return callback(uploadFiles);
}

这是我调用上传函数的函数，我想我做错了，我得到Callback is not a function作为错误...请指导我

function sendMail(req, res) {
    var data = req.body;
     upload(req,res);
// checking the condition if the file has been uploaded
    if (uploadFiles) {
        data_to_send.attachments = [{
            filename: 'file1' + uploadFiles.file1ext,
            filePath: uploadFiles.file1Path 
        }, {
            filename: 'file2' + uploadFiles.file2ext,
            filePath: uploadFiles.file2Path
        }]
    }
    console.log(data_to_send.attachments)
    smtpTransport.sendMail({
            from: data_to_send.from,
            to: data_to_send.to,
            subject: data_to_send.subject,
            atachments: data_to_send.attachments,
            text: data_to_send.text,
            html: data_to_send.html
        },
//.........

Answer 1

问题是，在您的上传函数中，您没有检查回调是否实际传递(并且不是未定义)。另外，您没有返回您的值，您实际上正在返回任何回调正在返回的内容。

下面是一些可能对您有帮助的代码:

// inside your upload function
var uploadFiles = {
        ext1: path.extname(req.files.file1.originalname),
        path1: req.files.file1.path,
        ext2: path.extname(req.files.file2.originalname),
        path2: req.files.file2.path
    }
if (callback) {
    callback(uploadFiles);
}

//inside your sendMail (notice the 3rd parameter passed to upload)
upload(req, res, function (uploadFiles) {
    if (uploadFiles) {
        data_to_send.attachments = [{
            filename: 'file1' + uploadFiles.file1ext,
            filePath: uploadFiles.file1Path 
        }, {
            filename: 'file2' + uploadFiles.file2ext,
            filePath: uploadFiles.file2Path
        }]
    }
    // rest of the code goes here, inside the callback.
});

现在您将真正按照您的意愿在回调中收到文件。