Allow specifying the groupBy feature

[ds-onv]

Hey Payload Team & Contributors!

I would like to propose an enhancement to the groupBy feature for collection list views:
Currently, the groupBy property in a collection's admin configuration accepts a boolean to enable the grouping UI. I propose extending this functionality in two ways:

• Allow developers to specify a default field for grouping when the list view is first loaded.
• Allow developers to define a specific list of fields that are available for grouping in the dropdown menu.

Problem & Motivation

In many use cases, there is a primary field that is the most logical grouping criterion. Requiring users to manually select this field adds a repetitive step. Setting a default would improve the user experience by presenting a more organized view immediately.

Furthermore, not all fields are suitable for grouping. Allowing every field to appear in the group-by dropdown can clutter the UI with irrelevant options (e.g., grouping by a unique fields like ids, descriptions... is not useful). Limiting the available options would guide the payload users and make the interface cleaner.

By allowing a default field and a list of allowed fields to be set, we can:

• Improve User Experience: Present a more organized and intuitive view immediately, reducing unnecessary clicks and decluttering the UI.
• Provide Developer Control: Give developers more control over the default presentation and available interactions for their data structures in the admin panel.

Proposed Solution

I suggest the groupBy property be enhanced to accept a string for a default field, an array of strings for allowed fields, or an object to specify both.

Current Implementation:
The groupBy property only enables the feature.

const Tasks: CollectionConfig = {
  slug: 'tasks',
  admin: {
    // Only enables the UI control for grouping
    groupBy: true,
  },
  // ...
};

Proposed Implementation:
The groupBy property could be expanded to offer more granular control.

1. Specify a default field:

   admin: {
     // Enables the feature AND groups by the 'status' field by default.
     groupBy: 'status', 
   },

2. Specify allowed fields for grouping:

   admin: {
     // Enables grouping and only shows 'status' and 'priority' in the dropdown.
     groupBy: ['status', 'priority'], 
   },

3. Combine both using an object (most flexible):

   admin: {
     groupBy: {
       default: 'status', // The field to group by on page load.
       options: ['status', 'priority'], // The only fields available in the grouping dropdown.
     },
   },

This structure could maintain backward compatibility. If groupBy is true, the current behavior persists. The new options would provide a small but powerful improvement to the admin UI's usability and developer control.

Thank you for your time and for considering this feature request.