CODEWITHSUNDEEP
gulp
Zasz
Zasz

Reputation: 12538

Running pipeline section multiple times with different arguments for concat step

I'm a fan of the files object format

files: {
    'dest/a.js': ['src/aa.js', 'src/aaa.js'],              // key: value
    'dest/a1.js': ['src/aa1.js', 'src/aaa1.js'],
}

I have a gulp task that concats source files like

gulp.task('cat', function() {
     gulp.src( <value-goes-here> )
     .
     <many pipeline steps>
     .
     .pipe(concat(<key-goes-here>))
     .pipe(gulp.dest('target/')
     .
     <more pipeline steps to be run on 'dest/a.js' and 'dest/a1.js'>
     .
});

Is there a streaming way to extend this task so that I get 1 bundle file for each key-value in files ?

I would like to NOT create one task per key-value pair, as I would like to continue piping more steps even after the last .pipe(gulp.dest('target/');

If I'm approaching this problem in wrong way, is there a better way?

Thank you in advance!

Rob Rich's answer works, Heres working version :

var Q = require('q');
var gulp = require('gulp');
var concat = require('gulp-concat');

var files = {
    'a.js': ['src/aa.js', 'src/aaa.js'],
    'a1.js': ['src/aa1.js', 'src/aaa1.js'],
};

gulp.task('cat', function() {
    var promises = Object.keys(files).map(function (key) {
        var deferred = Q.defer();
        var val = files[key];
        console.log(val);
        gulp.src(val)
            .pipe(concat(key))
            .pipe(gulp.dest('dest/'))
            .on('end', function () {
                deferred.resolve();
            });

        return deferred.promise;
    });
    return Q.all(promises);
});

Upvotes: 0

Views: 758

Answers (1)

robrich
robrich

Reputation: 13205

Try this:

var Q = require('q');

gulp.task('cat', function() {
    var promises = Object.keys(files).map(function (key) {
        var deferred = Q.defer();
        var val = files[key];

        gulp.src(val)
            .
            <many pipeline steps>
            .
            .pipe(concat(key))
            .pipe(gulp.dest('target/')
            .
            <more pipeline steps to be run on 'dest/a.js' and 'dest/a1.js'>
            .
            .on('end', function () {
                deferred.resolve();
            });

        return deferred.promise;
    });
    return Q.all(promises);
});

You can also accomplish a similar scenario by using streams instead of promises by using combined-stream or stream-combiner packages.

Upvotes: 2

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