how to dynamically build watch task's targets? - gruntjs

Question

using gurunt syncall, I want to dynamically sync every dir(and new dir created in the futrue) in project root except 'node_modules' dir to another dir.
using grunt watchall, I want to watch those dirs, when there are some changes in a dir, I want to automaticlly run the corresponding sync task.
here is my project root's structure:
├── Gruntfile.js
├── addon1
│   └── a.toc
├── adon3
│   └── 3.toc
├── node_modules
│   ├── grunt
│   ├── grunt-contrib-watch
│   └── grunt-sync
└── package.json
the grunt syncall command is ok, here is the result:
➜ testsync grunt syncall
Running "config" task
Running "sync:addon1" (sync) task
Running "sync:adon3" (sync) task
Done, without errors.
but the grunt watchall not ok. can you tell me why watchall tasks not work and how to fix it?
I start the command, and change and save the file '3.toc' in dir 'adon3', then grunt say:
➜ testsync grunt watchall
Running "config" task
Running "watch" task
Waiting...
>> File "adon3/3.toc" changed.
Running "sync:adon3" (sync) task
Verifying property sync.adon3 exists in config...ERROR
>> Unable to process task.
Warning: Required config property "sync.adon3" missing. Use --force to continue.
Aborted due to warnings.
here is my Gruntfile.js:
module.exports = function(grunt) {
grunt.initConfig({});
var destdir = "/Users/morrxy/project/testdest/";
// dynamic config sync and watch's targets for every dir except for node_modules
grunt.registerTask('config', 'config sync and watch', function() {
grunt.file.expand({filter: 'isDirectory'},
['*', '!node_modules']).forEach(function(dir) {
// config sync's targets
var sync = grunt.config.get('sync') || {};
sync[dir] = {
files: [{
cwd: dir,
src: '**',
dest: destdir + dir
}]
};
grunt.config.set('sync', sync);
// config watch's target
var watch = grunt.config.get('watch') || {};
watch[dir] = {
files: dir + '/**/*',
// is next line has problem?
// running 'grunt watchall'
// when I change and save the file '3.toc' in dir 'adon3', terminal say:
// >> File "adon3/3.toc" changed.
// Running "sync:adon3" (sync) task
// Verifying property sync.adon3 exists in config...ERROR
// >> Unable to process task.
// Warning: Required config property "sync.adon3" missing.
// but why 'grunt syncall' can work?
tasks: 'sync:' + dir
};
grunt.config.set('watch', watch);
});
});
grunt.loadNpmTasks('grunt-sync');
grunt.loadNpmTasks('grunt-contrib-watch');
grunt.registerTask('syncall', ['config', 'sync']);
grunt.registerTask('watchall', ['config', 'watch']);
};

Answer 1

Finally, I solved this problem. I add a github repo for this question. If you want test, you can clone it run it locally. https://github.com/morrxy/dynasync
The reason watchall can watch files changes but can't run the corresponding sync task is that when watch find files changed, the config for each sync is finnished running, so the config for that sync target is gone, we didn't save the running config any where. So to solve this problem, we could add the config task into the watch task before the sync task, like this tasks: ['config_sync', 'sync:' + dir].
in new Gruntfile.js, I split the config task to two task, one for config watch, one for config sync, in the watch task, using the config sync task. Here is the new Gruntfile.js
module.exports = function(grunt) {
var destdir = "/media/data/projects/dynasync_dest/";
grunt.loadNpmTasks('grunt-sync');
grunt.loadNpmTasks('grunt-contrib-watch');
// dynamic config sync's targets for every dir except for node_modules
grunt.registerTask('config_sync', 'dynamically config sync', function() {
grunt.file.expand({filter: 'isDirectory'},
['*', '!node_modules']).forEach(function(dir) {
// config this dir's sync target
var sync = grunt.config.get('sync') || {};
sync[dir] = {
files: [{
cwd: dir,
src: '**/*',
dest: destdir + dir
}]
};
grunt.config.set('sync', sync);
});
});
// dynamic config watch's targets for every dir except for node_modules
grunt.registerTask('config_watch', 'dynamically config watch', function() {
grunt.file.expand({filter: 'isDirectory'},
['*', '!node_modules']).forEach(function(dir) {
// config this dir's watch target
var watch = grunt.config.get('watch') || {};
watch[dir] = {
files: dir + '/**/*',
// this line solve the problem
// when find file change, first dynamically config sync and then sync the dir
tasks: ['config_sync', 'sync:' + dir]
};
grunt.config.set('watch', watch);
});
});
grunt.registerTask('syncall', ['config_sync', 'sync']);
grunt.registerTask('watchall', ['config_watch', 'watch']);
grunt.registerTask('default', ['watchall']);
};
This time, when watch find file changes, it can run the corresponding sync task. like this
grunt watchall
Running "config_watch" task
Running "watch" task
Waiting...
>> File "adon3/3.toc" changed.
Running "config_sync" task
Running "sync:adon3" (sync) task
Done, without errors.
Completed in 0.888s at Thu Apr 10 2014 14:01:26 GMT+0800 (CST) - Waiting...