9
Trigger.old in Salesforce | Context Variables in Apex Triggers
Chapter Topics
- Basics of Triggers
- When to use triggers
- Types of Apex Triggers in Salesforce
- Trigger Order of Execution
- Trigger Context Variables in Salesforce
- Trigger.new in Salesforce| Context Variables in Apex Triggers
- Trigger.old in Salesforce | Context Variables in Apex Triggers
- Trigger.newMap in Salesforce| Context Variables in Apex Triggers
- Trigger.oldMap in Salesforce| Context Variables in Apex Triggers
- Trigger Exceptions
- Best Practice in Triggers
- Trigger Helper Class Pattern
Trigger.old in Salesforce returns a list of the old version of sObject records, and is available in update and delete triggers.
Trigger.old in Salesforce Example:
| trigger OpportunityTrigger on Opportunity (before update) { for (Opportunity oldOpp: Trigger.old) { for (Opportunity newOpp: Trigger.new) { if (oldOpp.Id == newOpp.Id && oldOpp.Amount != newOpp.Amount) { newOpp.Amount.addError(‘Amount cannot be changed’); } } } } |
Here, Trigger.old helps compare the old and new values of Opportunity records to ensure that the Amount field is not changed.
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