Fix: Changing sorting direction on patterns does nothing.

[jorgefilipecosta]

The sorting direction controls are not working for patterns, that happens because we don't include a default sorting field when changing the direction, this PR fixes the issue.

Now when changing the sorting direction, if no sorting field is set changing the sorting direction assigns the first sortable field as the sort-by field.

This bug was reported at #64380 (review) by @t-hamano.

Testing Instructions

Go to the patterns sections, open the view configuration UI and verify the sort controls work as expected.

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[t-hamano]

Thanks for the quick fix!

This PR works as expected, but I have two questions:

• Why doesn't this issue occur in Templates or Pages? Sort by never seems to be undefined there 🤔 Are the initial values ​​of the Sort By explicitly set for these?
• Is it possible that the first field where enableSorting is not false doesn't match the field when shown in the Sort By?

[jorgefilipecosta]

Hi @t-hamano, excellent questions.

• Why doesn't this issue occur in Templates or Pages?

In both of these cases, there is a default sorting passed on the view, on Templates ascending by title on pages descending by date. So the bug is not noticeable.

Is it possible that the first field where enableSorting is not false doesn't match the field when shown in the Sort By?

No that will not happen because the select HTML element shows the first option element as the selected option.
For example, in this sample, the selected element will be "One"

<select>
  <option value="1">One</option>
  <option value="2">Two</option>
  <option value="3">Three</option>
  <option value="4">Four</option>
  <option value="5">Five</option>
</select>

In our code, we filter the fields for sortable and pass each field as an option, in the order they appear, so the first option will appear as selected.

[t-hamano]

Thank you for the detailed explanation! If so, I think this PR makes sense 👍