Config request: maxTrue Constraint for Boolean Fields in Arrays/Collections

[jmcapra]

e.g. A common use case for this feature would be managing a collection or array of contacts with an isPrimary checkbox field, ensuring that only one contact can be marked as primary per organisation.

While I'm sure it's possible to do with hooks/validation and custom components (for front end), it would be great to see this as a config option.

Proposed configuration

1. Simple scalar constraint (max N across entire array/collection):

// In Organisation.contacts[] array
    {
      name: 'isPrimary',
      type: 'checkbox',
      defaultValue: false,
      maxTrue: 1,
    }

2. Grouped constraint (max N within group, across array/collection):

This would allow defining a groupBy key to enforce the constraint within subsets of the collection.

// In Contacts collection
      maxTrue: {
        groupBy: 'parentOrganisation',
        maxPerGroup: 1,
      }

Thoughts?

• Would this align with existing validation patterns in the framework?
• Any guidance or tips on implementing this via the extendable config system?

Looking forward to your insights!

[jmcapra]

Related: passing the current object to admin.condition could help here as well on the UI side of things. e.g. to compare the value of the last edited field against siblingData

(property) condition?: Condition<any, any> | undefined
You can programmatically show / hide fields based on what other fields are doing. This is also run on the server, to determine if the field should be validated.