Grunt: How to build the files object dynamically - node.js

Question

I must be missing something very simple here. I'm trying to write a function task that deals with files. The Grunt API docs mention that you can [Build the files object dynamically], but for some reason I can't get this to work. A simplified version of my Gruntfile.js file looks like this:
module.exports = function(grunt) {
grunt.initConfig({
proj: {
build: {
files: [{
expand: true,
cwd: 'src',
src: ['**/*.js'],
dest: 'dist'
}]
}
}
});
grunt.registerTask('proj', function(){
var files = grunt.config('proj.build.files');
console.log(files);
});
};
I expect the log to show a list of file mappings from the src directory to the dist directory. What actually gets logged is the object proj.build.files from the config, like this:
Running "proj:build" task
[ { expand: true, cwd: 'src', src: [ '**/*.js' ], dest: 'dist' } ]
Done, without errors.
The API docs only talk about this type of configuration in terms of other tasks. I tried looking through the uglify task to see how the file mappings are retrieved, but I couldn't figure it out.

Answer 1

Here is the workaround I found to dynamically build filesets for Grunt tasks:
uglify: {
app: {
files: [{
src: '{<%= _prefixSrc(pkg.target, pkg.resources.js) %>}', // Note the brackets!
dest: '<%= pkg.target %>min/<%= pkg.name %>.min.js'
}]
}
},
_prefixSrc: function(prefix, files) {
return files.map(function(file){
return prefix + file;
});
},
See also this issue/feature request on GitHub and feel free to comment it if you find it useful: https://github.com/gruntjs/grunt/issues/1307

Answer 2

You can use rename function to change file name is files object like below...
build: {
files: [{
expand: true,
cwd: 'src',
src: ['**/*.js'],
dest: 'dist',
rename: function(dest, src) {
/*
rename logic
you will have access to src and dest name and can return desirect name from this function.
*/
return src+123;
}
}]
}