How to: Convert a file already stored

You may want to adjust a bunch of images that you've already stored. This can be done easily by streaming out of the store and then back into it. The following example is for illustration purposes, but you should not use it on production data unless you have a throttled queue in a separate process or only a very small number of images.

Images.find().forEach(function (fileObj) {
  var readStream = fileObj.createReadStream('images');
  var writeStream = fileObj.createWriteStream('images');
  gm(readStream).swirl(180).stream().pipe(writeStream);
});

Note that you could also pipe the readStream from one store to the writeStream from another store to move files between stores, for example if you decide to use a different storage adapter and need to quickly and easily migrate the data. (We have not tested this, but it should be possible.)