Allow a query to sort based on an object value field

[acinader]

Currently, if one tries to sort a query on a field in an object field, parse generates an error:

Type: Parse\ParseException
Code: 105
Message: Invalid field name: trendRankTopic.popular.

due to the check in the database controller here:

parse-server/src/Controllers/DatabaseController.js

Line 903 in 3b40d22

if (!SchemaController.fieldNameIsValid(fieldName)) {

This is not the same, though related to: #2113

An example would be an object:

{ sortField: { value: 10 } }

with a Query:

new Parse.Query('Test').addAscending('sortField.value').first()

generates the above error

[flovilmart]

What error would do you expect? Or would you expect sorting to work on objects?

[acinader]

one sec and I'll open the pr with the failing test and my proposed solution :).

[flovilmart]

Even better :)

[acinader]

@flovilmart any thoughts on #4806

I'm currently running our production on that branch which ain't a great long-term solution.

Anything I can explain as to why its an issue in the first place
or the solution I chose and why.

Some things I'd appreciate your considering: Is there a use case that this change would cause a breakage? is there a use case where my change will allow an introduction of 'bad schema' that could cause mayhem? Is there coverage I could write to test?

And finally, any suggestion on who I might ping to look at why Postgress is failing my test and what a solution might be?

[flovilmart]

I don’t think it’s a bad idea to introduce sorting on nested keys, Postgres support could come later. It can be gated with it_only_db instead of a simple it.

I don’t believe it is something we may regret in then future, however, I’m quite not understanding the change / i believe it’s not the proper resolution :)

[acinader]

I'll gate the test and add more explanation to the pull request. I agree that it is low risk. Having looked at it, I do think its the right solution, however, I'm super mindful of the fact that my ability to reason about that code is pretty limited :). Thanks!

[flovilmart]

CAN we add a small comment as for the change then in the code? So anyone that stumbled upon it is able to get a good idea of what’s going on?

[acinader]

done.

[wret]

Sorting based on object still not working on version 2.8.2.

[NicksonYap]

@wret
It is enabled in 2.8.4: "Allow sorting an object field (#4806)"
https://github.com/parse-community/parse-server/blob/2.8.4/CHANGELOG.md

However, it does not seem like it's supposed to order by related object's field

Tried this and has totally no effect:

      query.include('subzone');
      query.include('subzone.zone'); 
      query.addAscending('subzone.zone.title')  //no effect on result, no error
      query.addAscending('subzone.title') //no effect on result, no error
      query.addAscending('title') //sorts by title

@flovilmart @acinader
After upgrading from 2.8.2 to 2.8.4 query.ascending() no longer reports any error if the field does not exist
is it because of this sort by object field feature?