Set checkbox based on values in a related list?

Question

I was wondering if there is a way to achieve the following:

1) I have an "assignment" related list attached to my contact (i.e. a contact can have multiple assignments)

2) each assignment has a checkbox called "active"

3) I have a checkbox on my contact called "has active assignments"

4) is there a way to make contact."has active assignment" = true if any of the contacts assignments are active?

Thank you!

Answer 1

Assuming assignment is a custom object with a masterdetail to contact all you need to do is create a rollup summary on contact which sums the assignments that have their active__c field set to true and convert the contact's "active" checkbox to a formula field which checks if the rollup summary's value is greater than 0.