Gulp: How to set dest folder relative to processed file (when using wildcards)?

Question

Under my assets/ folder, I have numerous subfolders, each containing an arbitrary number of images, like so:

assets/article1/
assets/article2/

I'm trying to write a gulp task to locate all .jpg images within and generate their thumbnail versions, to be saved in a thumbs/ subfolder within the folder where each file resides:

assets/article1/               # original jpg images
assets/article1/thumbs/        # thumbnail versions of above..
assets/article2/
assets/article2/thumbs/

I've been trying various approaches but no luck. The closest I've come is:

gulp.task('thumbs', function () {
    return gulp.src( './assets/**/*.jpg' )
        .pipe( imageResize( { width: 200 } ) )
        .pipe( gulp.dest( function( file ) { return file.base + '/thumbs/'; } ) );
});

However, this creates a single thumbs\ folder at the root of assets\

assets/article1/
assets/article2/
assets/thumbs/article1/
assets/thumbs/article2/

Is there a good info on the paths and wildcards anywhere? Clearly I'm not handling it well..

Answer 1

You could use path.dirname for that: http://nodejs.org/api/path.html#path_path_dirname_p

// require core module
var path = require('path');

gulp.task('thumbs', function () {
    return gulp.src( './assets/**/*.jpg' )
        .pipe( imageResize( { width: 200 } ) )
        .pipe( gulp.dest( function( file ) { return path.join(path.dirname(file.path), 'thumbs'); } ) );
});

Answer 2

Here's what worked for me given the following directory structure (I simplified a bit to focus on just getting the files in the right place)

assets/article1/1.jpg
assets/article2/2.jpg

with a desired outcome of

assets/article1/1.jpg
assets/article1/thumbs/1.jpg
assets/article2/2.jpg
assets/article2/thumbs/2.jpg

Here's what worked for me (modified from this recipe https://github.com/gulpjs/gulp/blob/master/docs/recipes/running-task-steps-per-folder.md)

var gulp = require('gulp'),
    rename = require('gulp-rename'),
    path = require('path'),
    fs = require('fs');

var scriptsPath = 'assets'; // folder to process

function getFolders(dir) {
    return fs.readdirSync(dir)
      .filter(function(file) {
        return fs.statSync(path.join(dir, file)).isDirectory();
      });
}

gulp.task('thumbs', function() {
   var folders = getFolders(scriptsPath);

   return folders.map(function(folder) {
      return gulp.src(path.join(scriptsPath, folder, '/**/*.jpg'))
        .pipe(rename({dirname: folder + '/thumbs/'}))
        .pipe(gulp.dest(scriptsPath));
   });
});