AWS-SDK JS

• https://stackoverflow.com/questions/26726862/how-to-determine-if-object-exists-aws-s3-node-js-sdk

// Using callbacks
s3.headObject(params, function(err, metadata) {
  if (err && err.code === "NotFound") {
    // Handle no object on cloud here
  } else {
    s3.getSignedUrl("getObject", params, callback);
  }
});

// Using async/await (untested)
try {
  const headCode = await s3.headObject(params).promise();
  const signedUrl = await s3.getSignedUrl("getObject", params).promise();
  // Do something with signedUrl
} catch (headErr) {
  if (headErr.code === "NotFound") {
    // Handle no object on cloud here
  }
}

Mongodb $in

• https://stackoverflow.com/questions/8303900/mongodb-mongoose-findmany-find-all-documents-with-ids-listed-in-array

model.find(
  {
    _id: {
      $in: [
        mongoose.Types.ObjectId("4ed3ede8844f0f351100000c"),
        mongoose.Types.ObjectId("4ed3f117a844e0471100000d"),
        mongoose.Types.ObjectId("4ed3f18132f50c491100000e")
      ]
    }
  },
  function(err, docs) {
    console.log(docs);
  }
);