CODEWITHSUNDEEP
javascriptcsslessgulpgulp-less
mikemaccana
mikemaccana

Reputation: 123570

Gulp less not handling includes properly, included variables not defined

I am using less and Grunt, and am moving to gulp.

My less works. When I run:

lessc public/less/myapp.less

I get working output with no errors. All my less, including includes, is in public/less, BTW. Here is my gulpfile:

var gulp = require('gulp');
var prefixer = require('gulp-autoprefixer');
var less = require('gulp-less');

gulp.task('compileLess', function () {
  gulp
    .src('./public/less/*')
    .pipe(less({
      paths: ['./public/less'], // Search paths for imports
      filename: 'myapp.less'
    }))
    .pipe(gulp.dest('./public/css'));
});

// The default task (called when you run `gulp`)
gulp.task('default', function() {
  gulp.run('compileLess');

  // Watch files and run tasks if they change
  gulp.watch('./public/less/*.less', function(event) {
    gulp.run('less');
  });
});

When I run gulp, I get:

~/Documents/myapp: gulp
[gulp] Using file /Users/me/Documents/myapp/gulpfile.js
[gulp] Working directory changed to /Users/me/Documents/myapp
[gulp] Running 'default'...
[gulp] Running 'compileLess'...
[gulp] Finished 'compileLess' in 11 ms
[gulp] Finished 'default' in 41 ms

stream.js:94
      throw er; // Unhandled stream error in pipe.
            ^
Error: variable @brightblue is undefined

@brightblue is defined, in a file imported at the start of myapp.less.

@import "./colors.less";
body {
  background-color: @brightblue;
}

Upvotes: 23

Views: 18573

Answers (4)

Pierlo Upitup
Pierlo Upitup

Reputation: 1612

Another cause might be that you're using @import (inline) in your main.less, which will cause the imported file to not be processed.

See http://lesscss.org/features/#import-options

Upvotes: 0

user2331095
user2331095

Reputation: 6707

Here is my working version, using gulp-watch and gulp-connect for live reload.

gulp.task('less:dev', function () {
    gulp
      .src('app/styles/**/*.less', {read: false})
      .pipe(watch(function () {
        return gulp
          .src('app/styles/main.less')
          .pipe(less())
          .pipe(gulp.dest('app/styles/'))
          .pipe(connect.reload());  
    }));
});

Upvotes: 1

mikemaccana
mikemaccana

Reputation: 123570

The difference was what I was compiling:

  • When I ran lessc myapp.less, I was compiling the main less file and it's dependencies
  • When I ran gulp using the gulpfile above, I was compiling each less file individually, because gulp.src was *.less not myapp.less. Since these less files are only ever loaded from the main less file, they didn't have @imports for the things they depend on (because myapp.less depends on them). Eg, there's no point importing, say, 'theme.less' in every individual file rather than just importing it first in myapp.less.

Here's the working version:

// Run 'gulp' to do the important stuff
var gulp = require('gulp');
var prefixer = require('gulp-autoprefixer');
var less = require('gulp-less');
var path = require('path');

gulp.task('less', function () {
  gulp
    .src('./public/less/myapp.less') // This was the line that needed fixing
    .pipe(less({
      paths: ['public/less']
    }))
    .pipe(prefixer('last 2 versions', 'ie 9'))
    .pipe(gulp.dest('./public/css'));
});

// The default task (called when you run `gulp`)
gulp.task('default', function() {
  gulp.run('less');

  // Watch files and run tasks if they change
  gulp.watch('./public/less/*.less', function(event) {
    gulp.run('less');
  });
});

Edit: see @noducks answer below for an improved version that works with the latest gulp.

Upvotes: 35

Sean McClory
Sean McClory

Reputation: 4283

Noticed a couple of gulp.run deprecation warnings were popping up there. This fixes them, and adds some error handling. I have a slightly different directory structure.

    'use strict';

    var gulp = require('gulp');
    var prefixer = require('gulp-autoprefixer');
    var less = require('gulp-less');
    var gutil = require('gulp-util');
    var plumber = require('gulp-plumber');

    gulp.task('less', function() {
        gulp
            .src('./less/app.less')
        .pipe(plumber(function(error) {
            gutil.log(gutil.colors.red(error.message));
            gutil.beep();
            this.emit('end');
        }))
        .pipe(less())
        .pipe(prefixer('last 2 versions', 'ie 9'))
        .pipe(gulp.dest('./css'));
    });

    gulp.task('less:watch', function(){
        gulp.watch(['./less/*.less', './less/module/*.less'], ['less']);
    });

    gulp.task('default', ['less','less:watch']);

Upvotes: 5

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