CODEWITHSUNDEEP
node.jsamazon-web-servicesasync-awaitaws-lambda
Royi Namir
Royi Namir

Reputation: 148514

AWS Lambda doesn't work with `async`, Only with callbacks?

I have a Lambda function in AWS using Node 8.1 which initiate MSSQL request ( to an external server , which is not in aws)

When I'm using the non async handler with non async code (but callbacks )— 

exports.handler = (event, context, callback) => {...}

— Everything is OK.

Proof: For this code, which uses callbacks- 

exports.handler = (event, context, callback) => {
     sql.connect(config, err => {
        if (err) {
          callback(err);
        } else {
          const req = new sql.Request();
          req.query(
            'select * from img.dbo.images where imageid = 1641',
            (error, result) => {
              if (error) {
                callback(error);
              } else {
                sql.close();
                callback(null, result.recordset);
              }
            }
          );
        }
      });
};

I get this response :

enter image description here

However , If I change the code to the async version : 

exports.handler = async (event, context, callback) => {
  try {
    let pool = await sql.connect(config);
    let result1 = await pool
      .request()
      .query('select * from img.dbo.images where imageid = 1641');

    callback(null, result1.recordset);
  } catch (err) {
    callback(err);
  }
};

— I get a Timeout error(sure it's related to a non-fulfill promise) :

enter image description here

Question

Why doesn't the async version work ? how can I make it work?

Upvotes: 2

Views: 2652

Answers (1)

James
James

Reputation: 82096

Remove the callback param and just return the result instead. Also, you can avoid catching errors unless you need to do any special handling

exports.handler = async (event, context) => {
  const pool = await sql.connect(config);
  return await pool
    .request()
    .query('select * from img.dbo.images where imageid = 1641');
}

Upvotes: 4

Related Questions