Asynchronous 删除mongoose数据库的Grunt任务

我试图创建一个grunt任务，通过mongoose删除mongodb数据库。连接挂起，我必须强制退出，它实际上并没有删除数据库或输出错误

var db = require('./db/schema');

grunt.registerTask('drop', 'drop the database', function() {
  // async mode
  var done = this.async();

  db.mongoose.connection.db.dropDatabase(function(err) {
    if(err) {
      console.log(err);
    } else {
      console.log('Successfully dropped db');
    }
    db.mongoose.connection.close(done);
  });

});

输出

$ grunt drop
Running "drop" task
Successfully connected to: mongodb://localhost/test
^C

---

终于在这里找到了解决我问题的方法：必须将所有东西都包装在connection.on中

grunt.registerTask('drop', 'drop the database', function() {
// async mode
var done = this.async();

db.mongoose.connection.on('open', function () { 
  db.mongoose.connection.db.dropDatabase(function(err) {
    if(err) {
      console.log(err);
    } else {
      console.log('Successfully dropped db');
    }
    db.mongoose.connection.close(done);
  });
});
});