Does not support .then functions

[jelordreygulle]

I wanted to use promise in querying file using grid fs .

works

 gfs.findOne({ _id: '54da7b013706c1e7ab25f9fa'}, function (err, file) {
    console.log(file);
  });

does not work using promise

 gfs.findOne({ _id: '54da7b013706c1e7ab25f9fa'}).then(function (file) {
        console.log(file);
      }).catch(function (err) {

    })