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Current & Previous Objects

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In this lesson, you will learn:

  • What current and previous hold
  • How to check if a field changed
  • When previous is empty

1 Now and before

In a business rule, you get two versions of the record. current is the record as it’s being saved. previous is the record as it was before this change. Comparing them tells you what changed. 🔍

An incident update shown as previous and current side by side. Previous: State In Progress, Priority 3, Assigned to Sam Lee, Short description VPN is slow. Current: State Resolved, Priority 3, Assigned to Sam Lee, Short description VPN is slow. The State row is highlighted because it changed. Below: current.state.changes() is true, current.state.changesTo(6) is true, and current.priority.changes() is false.
Figure 1. Only State changed, so only State’s checks are true.

2 Checking for changes

Method True when…
current.state.changes() State changed at all
current.state.changesTo(6) State changed to 6 (Resolved)
current.state.changesFrom(2) State changed from 2 (In Progress)
current.state != previous.state The same idea, done by hand
current.operation() Returns ‘insert’, ‘update’, or ‘delete’ 
(function executeRule(current, previous) {
  if (current.state.changesTo(6)) {        // just resolved
    gs.info(current.number + ' resolved by ' + gs.getUserName());
  }
  if (current.assigned_to.changes() && !previous.assigned_to.nil()) {
    current.work_notes = 'Reassigned from ' + previous.assigned_to.getDisplayValue();
  }
})(current, previous);

💡 Good to know: You can put these checks in the Condition field on the Advanced tab, like current.state.changesTo(6). Then the script only runs when it matters.

3 When previous is empty

Situation previous
Insert (new record) Empty. There was no “before”
Update in before or after rules ✅ The old values
Async rules ❌ Not available (null)
Display rules Not useful. Nothing is changing

⚠️ Heads up: Using previous in an async rule causes errors. If an async rule needs old values, save them in a field (or an event, Chapter 41) first.

⭐ Remember: current = new values. previous = old values (updates only, not async). Use changes(), changesTo(), changesFrom().

4 Let’s try it: log reassignments

  1. Create a business rule on Incident: SNWR log reassignment. When: before. Update: checked. Advanced: checked.
  2. Condition: current.assigned_to.changes()
  3. Paste the script above. Submit.
  4. Open an incident assigned to Sam Lee. Change Assigned to, then save. Check the work notes. Do you see “Reassigned from Sam Lee”?

5 Quick recap

  • current holds the new values being saved
  • previous holds the values before this update
  • changes(), changesTo(), changesFrom() spot changes
  • previous is empty on insert and null in async rules

6 Check yourself

Think of your answer first. Then tap to check.

1 Write a condition that’s true only when priority changes to 1. Show answer

current.priority.changesTo(1)

2 On an insert, what does previous hold? Show answer

Nothing useful. There were no old values.

3 Can you use previous in an async business rule? Show answer

No. It’s not available in async rules.

Nice work! You finished this lesson. 🎉

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