Change the definition of sort order to ASC|DESC

[zhujinxuan]

Currently order in SortPayload type definition is a general string, but it shall be ASC or DESC in accordance with the docs and sort clicks in Datagrid This PR changes the definition of order to ASC|DESC

I also changed some desc in spec or demo files to DESC, because, if we use Datagrid from the react-admin, then our order would be predefined DESC or ASC, not the small cased desc or asc.

[slax57]

Thanks for your contribution.

You are correct, there are places in the code where we actually expect the value to be one of these, but since it's not currently enforced, I'm afraid that restricting the allowed types may break things.
We must investigate to make sure that it doesn't break things in some edge cases.
But it's not top priority for us, so we won't do that in the near future.

[zhujinxuan]

Got it! I totally understand that there is a risk regarding the type definition change. I will leave this PR here and it is totally upon your decision on what to do with the PR.

[fzaninotto]

Hi, and sorry it took us so long to look at your PR. We're ready to move forward.

I've merged master to your branch to resolve conflicts, and now there are new errors. Would you mind taking a look?

Also, as there may be an impact on some codebases, I'd prefer that we publish this change in a minor release. Would you mind rebasing on next instead of master?

[zhujinxuan]

Yes, I will do that on Friday.
Done. Would you like to have a look again?

Would you like me making a new PR for the next branch and closing this PR? So the change will only affect the next major release rather than minor release.
I didn't know I can change the rebase here. So I will keep changes in this PR.

[slax57]

Code looks good to me, thanks!

[fkowal]

not to be a buzz kill

but this is a pain for ie. ra-data-hasura

where there are more sorting options
desc_null_last
or multicolumn sort {field: 'col1,col2', order: 'asc,desc'}

i'd revise the reasoning behind this change and revert the ts order: type back to string

[fzaninotto]

Thanks for your feedback.

Compound sort order values aren't compatible with our datagrid headers, which expect a single order. Can you explain how you manage datagrids in this case?