I know @Anna Asatryan‚ is the product manager working on groups, so tagging her for full visibility. Based on the "Tip" in this article, it looks like you can report on groups and sub groups to an extent... can you share a little bit more about what you're looking to do?
Good to hear from you Kyna - hope you're doing well!
When adding fields/groupings/filters to a report, we're only offered the home or primary option for groups/teams - we are trying to accomplish the same thing w/ subgroup. The ultimate goal is to use wildcards to dynamically filter reports based on subgroup association.
If it's worth your time and the ongoing maintenance, I expect you could create a calculated custom parameter that uses IF statements to build out each Sub Group's lineage as a workaround, and then filter off that parameter to find only the data you need.
Same realm of thought as Doug's suggestion; minus the calculated parameter: add metadata in Group Descriptions to better understand and categorize each group. This is a guiding principle we use to support platform governance.
We tag our groups, teams, job roles, and custom forms in their description field with certain attributes (using hashtags/codes) that help us understand the purpose that the object serves, where it falls in a larger hierarchy, and what may be impacted if we make changes to it. This enables list filtering on those objects (only show me custom forms associated with Legal), as well as smart typeaheads (only allow selection of Marketing Creative teams). In your example, you could filter for projects where "Group Description contains #MAR)
Same with teams and job roles. Other attributes we tag on those objects is what workflows are affected/impacted. Does a team exist because it's used in an assignment or approval workflow; or is it used to enable comment tagging/notifications; or is it used to grant access to certain spaces, etc. That gives us an idea of what might break if we update or remove a team.
Basically, since we can't attach custom forms on top of these objects, we use their description field to assign metadata to them that would otherwise exist on attached forms.
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I see this topic has re-surfaced, and have good news. Since Workfront released group object custom forms, this functionality is now possible.
You can add a calculated field to a Group custom form that will record the nested hierarchy of groups and subgroups. You can then filter using this calculated field.
E.g. in a project report, you can say "Show me a list of all projects associated to group XYZ, or any of XYZ's subgroups" even if XYZ is not a top level parent.
You can set your calculated fields to record group names or IDs (we add a field for both names and IDs for extra flexibility.)
In a Group custom form, add a calculated field "Group Hierarchy IDs" Add this expression to the calculation builder:
In that example, the group 6dc...2e5 is a subgroup of 6ad...0ae, which is a subgroup of top level parent 5cb...b79
With that field in place, subgroup filtering is enabled. "Project > Group > Group Hierarchy IDs contains 6add989b7a4746f68ff093eb19c000ae" will return all projects that are associated to that group or its subgroups, but not any projects associated to its parent groups.
The same can be done with group names. This is helpful for enabling views in a report where you might want to see a group's hierarchy, but I wouldn't use it for filtering unless your group names are very unique.
In a Group custom form, add a calculated field "Group Hierarchy" Add this expression to the calculation builder: