handling *no files* error in grunt.js

Question

I'm writing some grunt plugins. I'm using this.files.forEach to iterate over source files. This seems to be the recommended solution. The code of a task looks, more or less, like this:

grunt.registerMultiTask(..., ..., function(){
  // init
  this.files.forEach(function (f) {
    // do something
  }
});

this.files , console-logged, looks something like this:

[ { src: [Getter], dest: 'tmp/external-sources.json', orig: { src: [Object], dest: 'tmp/external-sources.json' } } ]

However I fell into trouble when there are no recognized source files. As far as I can see, the this.files.forEach iterates over existing files, so the [Getter] (don't know, what that is) doesn't execute an iteration for non-existent files.

Now, this is a problem for me, since I change file paths frequently. And if I misconfigure the new path, I don't get notified about invalid paths. The only way to handle this is to scan the long console output which is really frustrating for big projects. I'd like to be notified when source list is empty

---

The question is... in fact, the questions are: * how can I force grunt to shout, when there are no source files for a given task/target? * can I change this behavior globally? I mean, can I tell grunt to shout for empty source-list for all tasks? * did II misunderstand something? If so, please, correct me.

Answer 1

As far as I can see, the this.files.forEach iterates over existing files

The files object contains all src objects defined in your Gruntfile, including non existing files/paths. So it will iterate over non existing paths as well.

the [Getter] (don't know, what that is) doesn't execute an iteration for non-existent files

That's correct, the src method in the files object will only get an existing file.

I'd like to be notified when source list is empty

You can iterate over orig.src for each of your files and error handle from there.
Note that if your src is undefined or null , grunt will warn you and abort, which is the behavior you're looking for. You can use the --force flag to continue but I highly discourage it.

Example:

Gruntfile.js

module.exports = function(grunt) {

  grunt.initConfig({
    myTask: {
      dev: {
        files: [
          {src: 'existingFile.js', dest: 'newFile'},
          {src: 'nonExistingFile.js', dest: 'newFile2'}
        ]
      }
    }
  });

  grunt.loadTasks('my_tasks');

  grunt.registerTask('default', ['myTask']);

};

my_tasks/task.js

module.exports = function(grunt) {
    grunt.registerMultiTask('myTask', '', function() {
        this.files.forEach(function(f) {
            f.orig.src.forEach(function(src) {
                //do something with src
            });
        }); 
    });
};