Modernization of hooks and functions

[flovilmart]

Is your feature request related to a problem? Please describe.

Right now, we still rely on the legacy backbone style success / error callback methods. With node.js moving forward at an incredible pace, I believe it's time to make the cloud functions enter the 21st century supporting async / await, promises and more

Describe the solution you'd like

• Support promises, async/await in cloud code as valid return values for hooks and functions
• Mark calls to success / error callbacks deprecated in Cloud Code (with a big fat warning)
• Later on, remove success / error implementations

Cloud funcitons would look like:

Parse.Cloud.beforeSave('ClassName', async ({ object }) => {
    await doSomething();
    if (somethingsFishy(object)) {
        throw new Error('OOps')
    }
    return;
});

// Also valid
Parse.Cloud.beforeSave('ClassName', async ({ object }) => {
    await doSomething();
    if (somethingsFishy(object)) {
        return new Error('OOps'); // returning an error is also allowed
    }
});

For functions:

Parse.Cloud.define('MyFunction', async ({ params }) => {
    await doSomething();
    if (!param.isValid) {
        return new Error('OOps'); // returning an error is also allowed
    }
    return 'OK!';
});

cc: @acinader , @dplewis

[SebC99]

That would be great!
In my own code, as I wanted to use promises, I've defined this helper methods:

// Create a new parse cloud method with a promise
function createParseCloudFunction(name, promise) {
  return Parse.Cloud.define(name, (request, response) => {
    return promise(request)._thenRunCallbacks(sendResponse(response));
  });
}

// Create a generic response from a promise
function sendResponse(response) {
  return {
    success: function(result) {
      response.success(result);
    },
    error: function (error) {
      response.error(error);
    }
  }
}

which allows me to add a new cloud function by calling

createParseCloudFunction("MyFunction", {params, user, master} => { ... do something ... });

And I also have one for jobs:

function createParseJob(name, promise) {
  return Parse.Cloud.job(name, function(request, status) {
    return promise(request)._thenRunCallbacks(sendResponse(status));
  });
}

[flovilmart]

@SebC99 with the next release of the server the _ThenRunCallbacks will fail

[SebC99]

@flovilmart oh? You're removing Parse.Promise? Is there somewhere where this is described? Thanks for telling me anyway!! 🙏
EDIT: I've just saw #4925 well done!!

[oallouch]

Everybody's got a callback-to-promise wrapper.
No big deal, but if it's made core, it's a plus.

[flovilmart]

The thing is with the next version of the JS SDK, callbacks won’t work at all, the underlying code is removed.

I’ll update the README as well in the JS SDK

[flovilmart]

So there's this opened PR now #4933

Anyone wanting to do the migration and see how it goes?

You can use the https://github.com/parse-community/parse-server#version-3.0.0 branch in your package.json

[srameshr]

Promises, async/await in cloud code are already working.
Here is a chunk of code / pattern that I have been using for a long time:

Parse.Cloud.define('put_content', async (req, res) => {
      try {
        const data = await this.put_content(req, res);
        res.success({ data });
      } catch (e) {
        const { code, message } = errors.constructErrorObject(e.code || 500, e);
        errors.handleError({ code, message }, res);
      }
    });
  }

[flovilmart]

@srameshr yes, obviously, if you are using node > 8 you have async await. But the goal here is to remove .success and .error as they are from a time backbone style callbacks were all the rage. as we have promised and async await in node we don’t need this style.

[SebC99]

@flovilmart are you removing the Parse.Promise as well to replace them with native promise?
Then we'll have to change all the .done callback to .then callback, right?

[flovilmart]

Yes indeed, this comes with the JS SDK 2.0

[cleever]

Great! I have been writing some parse server code with typescript ( using async/await even if node < 8) and it will be awesome throw away some Parse.Promise wrappers and all that backbone style code.

[flovilmart]

I'll leave the branch open this week, before we make a release, this ways if there are issues or else, we should be able to fix them before hand.

[flovilmart]

You can all check the migration docs: https://github.com/parse-community/parse-server/blob/3e5d2581553ed41185b9cf60c4bd9ceb12f8152e/3.0.0.md