是否可以获取可读流中文件的信息？

Question

I am developing a sftp server with nodeJs and I need to upload a file. I am using this module : node-sftp-server

I got the event "writefile" there :

session.on("writefile", function (_path, readstream) {

        console.warn("Receipt file " + Path.basename(_path));
        var uploadParams = { Bucket: Vertigo.getenv('APP_S3_BUCKETNAME'), Key: Path.basename(_path), Body: readstream }
        s3.upload(uploadParams, function (err, data) {
            if (err) {
                console.warn(err, err.stack)
                return err;
            } else {
                console.log("File: " + data.Key + " successfully uploaded");
                /**
                 * AJOUTER FICHIER DANS MONGODB
                 */
                receiptFile.insert({
                    date: new Date(Date.now()),
                    userId: ObjectID(request.params.userId),
                    file: {
                        s3BucketName: data.Bucket,
                        s3ObjectName: data.Key,
                        name: data.Key,
                        //size: data.Contents.Size, //Comment récuperer la taille ?
                        // mimetype: file.mimetypes //Comment récuperer le mimeType?
                    }
                }, function (err, result) {
                    if (err) {
                        var deleteParams = { Bucket: Vertigo.getenv('APP_S3_BUCKETNAME'), Key: Path.basename(_path) }
                        //Si une erreur s'est produite, on supprime les fichiers insérés précèdemment pour que la bdd et minio soient toujours synchronisés
                        s3.deleteObject(deleteParams, function (err, data) {
                            if (err) {
                                console.warn(err, err.stack)
                            }
                            console.log(deleteParams.Key + " : Deleted from : " + deleteParams.Bucket)
                        })
                        return err;
                    }
                    else {
                        console.log("Mongodb : File inserted in our database");
                    }
                })
            }
        });
        readstream.on("end", function () {
            console.warn("File has been wrote");
        });
    });
});
});

When I put the file on sftp console, I got the _path which is the name of file and a readable stream. I need to do that in two step. Step 1 : I must upload the file on s3 SDK client (It actually works) Step 2 : I must register infos in mongoDB

But I need to know size and mimeType of the file to register it..

The s3.upload method only return the BucketName, the filename, and the location of the file in the Bucket.

How could I get the size and mimeType of the uploaded file ??

If someone could help me, I would be grateful :)

Answer 1

Try this :

s3.headObject({ Key: key, Bucket: bucket })
  .promise()
  .then(res => {
    const size = res.ContentLength;
    const type = res.ContentType;
  });

Look : http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#headObject-property