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The following code (+/-) abstracts out each individual step:
- But once you have the abstracted methods, how do you chain their results? This is where the waterfall approach from the Async NPM package comes in.
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Since you've already abstracted your methods, you may try something like this (+/-) to make them a little more waterfall friendly:
- And then you may try the simplest way you can think of asking waterfall to run:
- But that will fail to run because the syntax of the sentence has ended up being written in a manner where callback must be a variable that is already defined and ready to be used. Making an anonymous method here and bringing up the entire code bodies of the abstracted named-methods would defeat the readability and reuseability that we have been trying to achieve. Here's a tweak that will make it happen:
Friday, June 15, 2012
How to use named functions with Async waterfall in node.js
Lets start with a real world example where you want to create a user in CouchDB. This is a two step process that involves asking for a unique uuid and then creating a user based on that.
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Hey nice post, helped me a lot
ReplyDeleteOr you could just pass the functions as variables..
ReplyDelete// Works
async.waterfall([
getUUID,
createUser
],
function (err, result) {
console.log(result);
}
);
Error in your first thought solution is that the functions get called in place since you pass params to them.
// Does not work
async.waterfall(
[
getUUID (callback),
createUser(uuid, callback)
],
function (err, result) {
console.log(result);
}
);
Other then that, thank you very much!
Thanks for posting this, I found the example in the Github readme a little confusing, but this cleared it up!
ReplyDelete