How to retrieve the Metadata from nodejs aws s3 getObject callback data?

Question

I am trying to upload/download an audio chunk file to/from S3 using AWS node SDK. I have tried base64 approach and it works fine. But I am not able to get the Metadata back which I have bundled as part of upload params.

Below is the code snippet for upload along with meta info:

var myMetaInfo = "AdditionalInfo", dataToUpload = {Bucket: bucketName, Key:storageFolderFullPath , Body: myAudioFile.toString('base64'), Metadata: {metaInfo: myMetaInfo}};
s3.client.putObject(dataToUpload, function(err, data) {
    if (!err) {
        console.log("Successfully uploaded the file to ::" + dataToUpload.Bucket);            
    } else {
        console.log(" **** ERROR while uploading ::"+err);            
    }        
}); 

And this is the snippet for downloading the file. Metadata is not part of the callback data. I tried printing the callback 'data' to console and noticed that only the following params are available LastModified, ContentType, ContentLength, ETag, Body, RequestId

var dataToDownload = {Bucket: bucketName, Key: storageFolderFullPath}, originalFile, myMetaInfo;
s3.client.getObject(dataToDownload, function(err, data) {
    if (!err) {            
        originalFile = new Buffer(data.Body, 'base64');
        myMetaInfo = data.Metadata.metaInfo;
        console.log(" Meta info:: " + myMetaInfo);
        fs.writeFile(fileStoragePath, originalFile, function(err) {
            if (!err) {
                console.log(" File written!! ");
            } else {
                console.log(" Error while writing the file !!" + err);
            }
        });
    } else {
        console.log(" **** ERROR while downloading ::"+err);            
    }
});

Any pointers on what is wrong with my implementation? I have followed the documentation mentioned here

Any help is appreciated.

Answer 1

Is your metaInfo value a string?

Referencing the sdk api docs , Metadata is a string map (ala ~ Metadata: {metaInfo: "myMetaInfoString"} . I've tested your code using a string as the value for metaInfo and it does return correctly under the data.Metadata.metaInfo reference.