How can I implement this type of logic using Promises?

Question

I am fairly new to the world of Javascript promises and am having issues implementing the following:

var Promise = require('bluebird');
var jenkinsapi = require('jenkins-api');
var asyncJenkinsAPI = Promise.promisifyAll(jenkinsapi);
var jenkins = asyncJenkinsAPI.init("http://<user>:<password>@localhost:8080");

app.get('/api/servers', function(req, resp) {
    SavedJob.find({})
        .then(function(jobs) {
            return Promise.all(jobs.map(function(job){
                // do two calls with each job.name
                // build new data with the result of the two calls
                // return new data to next part of chain
                var job_status = jenkins.job_info(job.name, function(err, jobData) { return jobData; });
                var build_info = jenkins.last_build_info(job.name, function(err, buildData) { return buildData; });
                return {task_name: job_status.name,
                        status: STATUSMAP[job_status.color] || "UNKNOWN",
                        latest_build:
                            {
                                build_date: build_info.timestamp,
                                build_status: build_info.result,
                                build_number: build_info.number,
                                build_url: build_info.url
                            }
                        };
            }));
        })
        .then(function(results){
            console.log(results);
        });
    });

How can I best implement making two asynchronous calls inside the Promise.all() with each job.name and have the set of results at the end?

That's exactly how it works. I'm not sure what you are asking about. Just return a promise from the `map` callback. — Bergi, Aug 18 '16 at 14:48
[Promisify](http://stackoverflow.com/q/22519784/1048572) those callback-taking functions. — Bergi, Aug 18 '16 at 15:26
I think I am missing a crucial piece, when I do `Promise.promisifyAll(require('jenkins-api'))` I still get undefined values when logging to console. — Muttonchop, Aug 18 '16 at 15:37
Can you update your question to show what exactly you are doing? — Bergi, Aug 18 '16 at 15:40
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/121271/discussion-between-muttonchop-and-bergi). — Muttonchop, Aug 18 '16 at 16:02

Bergi · Accepted Answer · 2016-08-18T17:20:17.537

1

After having promisified jenkins, you will need to use the new promise-returning methods:

var job_promise = jenkins.job_infoAsync(job.name);
var build_promise = jenkins.last_build_infoAsync(job.name);

(you might want to pass {suffix: "_async"} as an option to promisifyAll for nicer method names).

Then combine those two promises (Promise.all/Promise.props/Promise.join):

return Promise.join(job_promise, build_promise, function(job_status, build_info) {
    return {
        task_name: job_status.name,
        status: STATUSMAP[job_status.color] || "UNKNOWN",
        latest_build: {
            build_date: build_info.timestamp,
            build_status: build_info.result,
            build_number: build_info.number,
            build_url: build_info.url
        }
    };
});

The rest of your code (mapping, chaining) is working fine.

edited Aug 18 '16 at 17:20

answered Aug 18 '16 at 16:20

Bergi

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After putting your solution into the code, I am getting that `name` is undefined. Also, using `Async` (and trying putting in `_async` into promisify) suffix returns an error saying they are not functions. – Muttonchop Aug 18 '16 at 17:02
Which name is undefined? The property? Is that an error? – Bergi Aug 18 '16 at 17:06
Yes, if you pass the suffix you'd have to use `.job_info_async(…)` and `.last_build_info_async(…)` of course instead of the default `Async` suffix – Bergi Aug 18 '16 at 17:07
`var asyncJenkinsAPI = Promise.promisifyAll(jenkinsapi);` and using `.job_infoAsync(…)` throws an TypeError saying it is not a function. – Muttonchop Aug 18 '16 at 17:11
That's weird, it should work. Maybe try `asyncJenkinsAPI.job_…`, otherwise open a bug with Bluebird. – Bergi Aug 18 '16 at 17:19
Regarding `job_status`, it doesn't throw an error about `name` being undefined, rather about accessing a `.name` property on `undefined`. I messed up the paramter name. But still, this is very weird, code evaluation should not even get till there if `job_infoAsync(…)` already threw. – Bergi Aug 18 '16 at 17:22
The solution to this ended up `promisify`-ing the individual call in the jenkins api. – Muttonchop Aug 18 '16 at 18:55
@Muttonchop Glad you found a solution :-) If my answer was helpful, please accept it. And file a bug with Bluebird that `promisifyAll` doesn't work for `jenkins-api`. – Bergi Aug 18 '16 at 19:15

How can I implement this type of logic using Promises?

1 Answers1