Shorten my asynchronous DB queries, using async.js module

Question

I am using the following frameworks/libraries:

Node.js
Express.js
node-mysql.js
async.js

I am making multiple asynchronous queries to my DB, but each subsequent query relies on the results of the previous query, so I decided to use the waterfall method.

Right now, my code looks like this (I simplified it with only 2 queries, but there are more):

async.waterfall([
    function(cb){
        db.query(insertQuery,values,cb);
    },
    function(results,_,cb){
       var lastInsertId = results.insertId;
       db.query(anotherInsertQuery,otherValues.concat(lastInsertId),cb);
    }
],callback);

But I found my code a bit messy, especially the function(cb) { ... } wraps.

Is there a way to get rid of those annoying function(cb){...} ?

@Jamal : Thanks for the edit. I wanted to tag my post with node-mysql.js, since it's related with that, but I couldn't create it (not enough reputation). Do you think you could do that ? — Waldo Jeffers
– Waldo Jeffers, Commented Aug 20, 2014 at 14:34
At the moment I don't think we need a node-mysql.js tag here — Simon Forsberg
– Simon Forsberg, Commented Aug 20, 2014 at 14:36
Welcome to Code Review btw, I don't find your question very clear. Are you asking if your implementation is good, or asking for alternative implementations? — Simon Forsberg
– Simon Forsberg, Commented Aug 20, 2014 at 14:36
@SimonAndréForsberg : Ok I understand. I first hesitated, because I thought it was too specific, but then found out that async.js existed, with only one question so... But anyway, thanks for the welcome ! Sorry about that, I would like to know what's the cleanest way to do what I'm trying to do using the async.js module. What methods (apply, waterfall...) or structure should I use ? Is that more clear ? Do you think I should edit my question ? — Waldo Jeffers
– Waldo Jeffers, Commented Aug 20, 2014 at 14:41
What exactly is the question @WaldoJeffers? Short and simple, because this is a pretty unclear question. — RubberDuck
– RubberDuck, Commented Aug 20, 2014 at 14:55

konijn · Accepted Answer · 2014-08-22 19:19:38Z

3

I think not.

Whereas you find the function(cb) { ... } wraps a bit messy, I think that this is the most elegant way to show readers that this is a separate functions, and that stuff is about to get asynchronous.. Again, compared to other approaches, this is quite clean.

Also, (I know this is just a small example), consider not using the lastInsertId variable. You could simply go for

async.waterfall([
    function(cb){
        db.query(insertQuery,values,cb);
    },
    function(results,_,cb){
       db.query(anotherInsertQuery,otherValues.concat(results.insertId),cb);
    }
],callback);

answered Aug 22, 2014 at 19:19

konijn

34.4k5 gold badges71 silver badges267 bronze badges

1

\$\begingroup\$ Thanks @konijn. I'll wait a bit to see if someone comes with another answer, and will accept yours otherwise. \$\endgroup\$

Waldo Jeffers
– Waldo Jeffers

2014-08-25 08:43:22 +00:00
Commented Aug 25, 2014 at 8:43

Add a comment |

Sᴀᴍ Onᴇᴌᴀ · Accepted Answer · 2025-10-07 05:27:19Z

One ES-6 technique is to use the await keyword. As the MDN documentation says:

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨March 2017⁩. ¹

Obviously that was was a few years after the code was posted, however it has been supported since NodeJS version 7.6² and hopefully the NodeJS version the code is running on is much greater given LTS. The documentation also states:

The await operator is used to wait for a Promise and get its fulfillment value. It can only be used inside an async function or at the top level of a module. ¹

I haven't used node-mysql.js, and am having difficulty finding the documentation and/or source of it (perhaps because it may not have been maintained in the past 11 years), however depending on its support for asynchronous queries, one could use a try/catch block (as the MDN documentation for await suggests), or possibly "handle rejected promises without a try block by chaining a catch() handler before awaiting the promise."³ to call the callback function.

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