使用mongoose,gridfs-stream和multer上传文件时出现MongoError

Question

我运行Express 4的使用multer,GridFS的流和猫鼬用MongoDB中,我尝试上传的文件,并将其流式传输到GridFS的.

执行此操作的快速路由定义为:

app.post('/uploadfile', function (req, res) {
    console.dir(req.files);

    // The mongodb instance created when the mongoose.connection is opened
    var db = mongoose.connection.db;

    // The native mongo driver which is used by mongoose
    var mongoDriver = mongoose.mongo;

    // Create a gridfs-stream
    var gfs = new Gridfs(db, mongoDriver);

    var file = req.files.myFile;

    var fileId = new ObjectId();

    console.log("Creating WriteStream");
    var writeStream = gfs.createWriteStream({
        _id: fileId,
        filename: file.originalname,
        mode: 'w',
        content_type: file.mimetype,
        metadata: {
            id: '123',
            number: '2',
            name: "Kenny Erasmuson"
        }
     });
     console.log("Created WriteStream");
     req.pipe(writeStream);
     console.log("Finished!");
});

快速应用程序运行后,将选择并上载文件(通过HTML multipart/form-data表单),节点服务器的输出为:

$ node server.js 
Listening on port 8001
{ myFile: 
    { fieldname: 'myFile',
    originalname: 'kenny-credit-rating.pdf',
    name: '1082e5071ede1002c4ae5be6123226d8.pdf',
    encoding: '7bit',
    mimetype: 'application/pdf',
    path: 'uploads/1082e5071ede1002c4ae5be6123226d8.pdf',
    extension: 'pdf',
    size: 110782,
    truncated: false,
    buffer: null } 
}
Creating WriteStream
Created WriteStream
Finished!
/Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/co nnection/base.js:246
    throw message;      
          ^
MongoError: The dollar ($) prefixed field '$conditionalHandlers' in '_id.$conditionalHandlers' is not valid for storage.
at Object.toError (/Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/utils.js:114:11)
at /Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/collection/core.js:569:27
at /Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:1157:7
at /Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:1890:9
at Server.Base._callHandler (/Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/base.js:448:41)
at /Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/server.js:481:18
at MongoReply.parseBody (/Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/responses/mongo_reply.js:68:5)
at null.<anonymous> (/Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/server.js:439:20)
at emit (events.js:95:17)
at null.<anonymous> (/Users/kenny/Dropbox/Dev/fileUploader/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:201:13)

有没有人有任何想法导致错误和如何解决？

Answer 1

问题在于您没有只将文件请求传递给gridfs-stream.使用Multer作为中间件捕获任何multipart/form-data发布请求.当流进来时,Multer(建立在Busboy上)监视on('field')和on('file')事件并相应地进行解析.你对Multer的管道不仅仅是一个档案.

因为Multer确实已经分析出你的这段代码工作正常req.files,并req.body通过了这一点:

   // Create a gridfs-stream
   var gfs = new Gridfs(db, mongoDriver);

   var file = req.files.myFile;

   var fileId = new ObjectId();

   console.log("Creating WriteStream");
   var writeStream = gfs.createWriteStream({
        _id: fileId,
        filename: file.originalname,
        mode: 'w',
        content_type: file.mimetype,
        metadata: {
            id: '123',
            number: '2',
            name: "Kenny Erasmuson"
        }
     });
     console.log("Created WriteStream");

但是你的代码遇到问题的地方出于上述原因:

 req.pipe(writeStream);

我还没有找到一种方法来流式传输multipart/form-data post请求,而不仅仅是直接将文件上传到GridFS.如果您的发布请求不包含文件以外的任何内容(表示表单中没有其他html输入字段),那么您可能需要考虑至少为此路由从中间件中删除Multer.

对于我的用例,我需要能够接收带有文本输入和文件上传的html表单帖子(我在上传时存储有关文件的元数据).以下是我用Multer完成所需的工作:

var uploadImg = function(req,res) {
      var writestream = gfs.createWriteStream({
        filename: req.files.file.name,
        mode:'w',
        content_type:req.files.file.mimetype,
        metadata:req.body,
      });
    fs.createReadStream(req.files.file.path).pipe(writestream);

    writestream.on('close', function (file) {
        res.send("Success!");
        fs.unlink(req.files.file.path, function (err) {
          if (err) console.error("Error: " + err);
          console.log('successfully deleted : '+ req.files.file.path );
        });
    });

};

默认情况下,Multer会将您的文件存储在磁盘上.一个快速的解决方案是创建一个读取流并将其直接传输回GridFS.写入完成后,删除tmp文件.

作为旁注,似乎有一些想法,最好只在需要它的路线上使用Multer作为中间件.你可以阅读更多关于这个想法在最后一节本.

更新

我想我已经找到了一种通过使用Skipper直接使用元数据直接传输到GridFS的方法.我正在查看我是否无法获得一些更新,这些更新将发送到带有 html表单上的文本输入并将其设置为元数据等的skipper-gridfs.对于skipper-gridfs的调整似乎很小.当它被刷新时我会更新.如果你看船长,请确保你认识到html表单输入的顺序(如果你有的话)确实很重要.