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Before & After Rules

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In this lesson, you will learn:

  • When before and after business rules run
  • What each one is good for
  • Why you don’t call current.update() in them

1 Before or after the save

When someone saves a record, ServiceNow writes it to the database. A business rule can run just before that write, or just after. That timing changes what the rule should do. ⏱️

The order of events when a record is saved. 1: the user clicks Update. 2: before business rules run and can change the current record or stop the save. 3: the record is written to the database. 4: after business rules run and update other records, like related incidents. 5: the user sees the saved form.
Figure 1. Before rules shape this record. After rules touch other records.

2 Before rules

A before rule runs before the database write. Any change you make to current is saved automatically. No extra save needed!

// before insert: tag network incidents
(function executeRule(current, previous) {
  if (current.category == 'network') {
    current.assignment_group.setDisplayValue('Network');
  }
})(current, previous);

Before rules can also stop a save:

if (current.short_description.nil()) {
  gs.addErrorMessage('Short description is required.');
  current.setAbortAction(true);
}

3 After rules

An after rule runs once the record is saved. Use it to update other records.

// after update on problem: note the fix on linked incidents
(function executeRule(current, previous) {
  var inc = new GlideRecord('incident');
  inc.addQuery('problem_id', current.sys_id);
  inc.addActiveQuery();
  inc.query();
  while (inc.next()) {
    inc.work_notes = 'Problem ' + current.number + ' was updated.';
    inc.update();
  }
})(current, previous);
Before After
Runs Before the database write After the database write
Best for Changing this record, checking values, stopping the save Changing other records
Needs current.update()? No (it’s saved automatically) No (don’t touch this record again)

⚠️ Heads up: Never call current.update() in a before or after rule on the same table. It saves the record again, which runs the rules again, and can loop or cause duplicate work.

⭐ Remember: Before = change this record. After = change other records. No current.update()!

4 Let’s try it: auto-assign network incidents

  1. Create a business rule on Incident: SNWR route network. When: before. Insert: checked.
  2. Filter Conditions: Category is Network. Check Advanced.
  3. In the script, set the assignment group to a group in your instance (use its name in setDisplayValue()). Submit.
  4. Create a network incident with no group. Save. Is the group filled in?

5 Quick recap

  • Before rules run before the save and can change or stop it
  • After rules run after the save and update other records
  • current.setAbortAction(true) stops a save (in before rules)
  • Don’t call current.update() in before or after rules

6 Check yourself

Think of your answer first. Then tap to check.

1 You want to fill in a field on the record being saved. Before or after? Show answer

Before.

2 You want to update child incidents when a problem changes. Before or after? Show answer

After.

3 How does a before rule stop a save? Show answer

current.setAbortAction(true)

Nice work! You finished this lesson. 🎉

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