Using a node module within a Grunt Task fails - node.js

Question

I'm trying to extract meta data from files read within a Grunt task.
executing: node test.js on this file:
var exif = require('exif2');
exif('fixtures/forest.png', function (err, o) {
console.log(arguments);
});
Produces the expected output
However, executing the grunt process: grunt projectJSON
module.exports = function (grunt) {
var exif = require('exif2');
return grunt.registerMultiTask("projectJSON", "Creates project JSON file.", function () {
exif('fixtures/forest.png', function (err, o) {
console.log(arguments);
});
});
}
** note that I am just testing with the fixtures/forest.png file
Produces no output whatsoever. The callback isn't even fired.
When I console.log exif, I get: [Function]
What am I missing? I think that the doesn't work is because of the grunt task, but I have no idea how to fix it. Wrapping it in a try-catch block produces nothing.

Answer 1

You need to make your projectJSON task asynchronous - Grunt is exiting before your exif callback is being invoked.
Have a look at the Grunt documentation on asynchronous tasks.
This is how you can make your task asynchronous:
module.exports = function (grunt) {
var exif = require('exif2');
grunt.registerMultiTask("projectJSON", "Creates project JSON file.", function () {
// Make task asynchronous.
var done = this.async();
exif('fixtures/forest.png', function (err, o) {
console.log(arguments);
// Invoke the task callback to continue with
// other Grunt tasks.
done();
});
});
}