Promises On Cloud Code

I'm writing a cloud code function for run many task after delete an object. How can I do this cleanly and without nesting? You can run tasks in parallel or it is better to have th

Solution 1:

Here find.then.delete is a series of tasks in a row. However, you can delete your hastags and activities in parallel since they don't seem to be dependent. Please check promises guide for more info. Your code can be shortened as below:

var Photo = Parse.Object.extend("Photo");

Parse.Cloud.afterDelete("Photo", function(request) {
  Parse.Cloud.useMasterKey();

  var photo = Photo.createWithoutData(request.object.id);

  var queryAct = new Parse.Query("Activity");
  queryAct.equalTo("photo", photo);
  queryAct.limit(1000);
  var promiseForActivities = queryAct.find().then(function (activities) {
    return Parse.Object.destroyAll(activities);
  });

  var queryTags = new Parse.Query("hashTags");
  queryTags.equalTo("photo", photo);
  queryTags.limit(1000);
  var promiseForHashtags = queryTags.find().then(function (hashtags) {
    return Parse.Object.destroyAll(hashtags);
  });

  return Parse.Promise.when([promiseForActivities, promiseForHashtags]).then(function () {
    console.log("Done");
  }, function (err) {
    console.error(err);
  });
});

Note that you don't need to create your own pointer objects like:

{
  __type: "Pointer",
  className: "Photo",
  objectId: "someId"
}

Rather you can use createWithoutData which is a shortcut for:

var Photo = Parse.Object.extend("Photo");
var p = new Photo();
p.id = "someId";

I also think that it could be enough to pass the request.object directly, like queryAct.equalTo("photo", request.object);