Show item categories in 'New Item' dialog

[daniel-beck]

This was one of the features added to the Jenkins 2.0 "New Item" dialog. Manuel removed it by default because categories weren't defined (#2191 (comment)), and later everyone seems to have forgotten about this.

Now that we're discussing Jenkins 3.0 is probably a good time to actually make this feature visible 🤣

Most of the commonly installed job types all support item categories (and those that don't haven't bothered with icons either):

Proposed changelog entries

• Group job types by category on "New Item" dialog.

Proposed upgrade guidelines

N/A

Submitter checklist

• (If applicable) Jira issue is well described
• Changelog entries and upgrade guidelines are appropriate for the audience affected by the change (users or developer, depending on the change). Examples
  • Fill-in the Proposed changelog entries section only if there are breaking changes or other changes which may require extra steps from users during the upgrade
• Appropriate autotests or explanation to why this change has no tests
• For dependency updates: links to external changelogs and, if possible, full diffs

Desired reviewers

@mention

Maintainer checklist

Before the changes are marked as ready-for-merge:

• There are at least 2 approvals for the pull request and no outstanding requests for change
• Conversations in the pull request are over OR it is explicit that a reviewer does not block the change
• Changelog entries in the PR title and/or Proposed changelog entries are correct
• Proper changelog labels are set so that the changelog can be generated automatically
• If the change needs additional upgrade steps from users, upgrade-guide-needed label is set and there is a Proposed upgrade guidelines section in the PR title. (example)
• If it would make sense to backport the change to LTS, a Jira issue must exist, be a Bug or Improvement, and be labeled as lts-candidate to be considered (see query).

[oleg-nenashev]

FWIW the Promoted Build plugin makes some of the standalone projects nested ones :)

I am fine with merging it though I do not see a bug UX improvement. Would be great to get extra feedback from the UX SIG. CC @fqueiruga @timja @uhafner

[fqueiruga]

LGTM but I do wonder if some items should be categorized again. For example, I'm wondering if the Pipeline family should be on it's own category, even as the first one.

[fqueiruga]

Can plugins define their own category?

[jglick]

jenkins/core/src/main/java/jenkins/model/item_category/ItemCategory.java

Line 115 in e377d84

@Extension(ordinal = Integer.MIN_VALUE)

vs.

jenkins/core/src/main/java/jenkins/model/item_category/NestedProjectsCategory.java

Line 40 in e377d84

@Extension(ordinal = -100)

does not seem to be working:

jenkins/war/src/main/js/add-item.js

Line 230 in e377d84

$.each(data.categories, function(i, elem) {

seems to ignore the order.

Not sure minToShow works either; never seems to be read. (And why would you ever set this to anything but 1 anyway?)

Can plugins define their own category?

Yes. Unfortunately NestedProjectsCategory ought to have been in cloudbees-folder but this was not done correctly, and as above, the handling of custom categories was apparently never tested.