Question

I have a node / angular project that uses npm for backend dependency management and bower for frontend dependency management. I’d like to use a grunt task to do both install commands. I haven’t been able to figure out how to do it.

I made an attempt using exec, but it doesn’t actually install anything.

module.exports = function(grunt) {

    grunt.registerTask('install', 'install the backend and frontend dependencies', function() {
        // adapted from http://www.dzone.com/snippets/execute-unix-command-nodejs
        var exec = require('child_process').exec,
            sys  = require('sys');

        function puts(error, stdout, stderr) { console.log(stdout); sys.puts(stdout) }

        // assuming this command is run from the root of the repo
        exec('bower install', {cwd: './frontend'}, puts);
    });

};

When I cd into frontend, open up node, and run this code from the console, this works fine. What am I doing wrong in the grunt task?

(I also tried to use the bower and npm APIs, but couldn’t make that work either.)

Answer 1

You need to tell grunt that you’re using an async method (.exec) by calling the this.async() method, getting a callback, and calling that when exec is done.

This should work:

module.exports = function(grunt) {
    grunt.registerTask('install', 'install the backend and frontend dependencies', function() {
        var exec = require('child_process').exec;
        var cb = this.async();
        exec('bower install', {cwd: './frontend'}, function(err, stdout, stderr) {
            console.log(stdout);
            cb();
        });
    });
};

See Why doesn’t my asynchronous task complete?