CODEWITHSUNDEEP
javascriptnode.jspromiseq
Fcoder
Fcoder

Reputation: 9216

Running sequential functions in Q Promise (Node.js)

I have two functions that return a Q Promise:

var q = require('q');

var get1 = function () {
    var deferred = q.defer();
    deferred.resolve('hello world');

    return deferred.promise;
};

var get2 = function () {
    var deferred = q.defer();
    deferred.resolve('hello world 2');

    return deferred.promise;
};

I can call each of them like this:

get1().then(console.log,console.error);

Right now, I want to sequentially call them. How?

I tried this:

q.fcall(self.get1)
        .then(self.get2);

but in this method how can I pass parameters to functions? How can I get resolve or reject values for each of them?

I want to run them sequentially even though one of them has an Async process in its body.

Upvotes: 0

Views: 241

Answers (1)

paulpdaniels
paulpdaniels

Reputation: 18663

If you use the chained response, that the value of the first Promise will get passed to the second through the continuation, so your get2 should accept an argument:

var get1 = function () {
    var deferred = q.defer();
    deferred.resolve('hello world');

    return deferred.promise;
};

var get2 = function (result) {
    var deferred = q.defer();
    deferred.resolve(result + 2);

    return deferred.promise;
};

//Then you can use it like so
get1().then(get2).then(console.log.bind(console), console.error.bind(console));

Also as a side note you should avoid using the defer api where possible, since it is considered an anti-pattern.

Upvotes: 1

Related Questions