List Custom Settings
By the end of this lesson, you'll be able to:
- Explain what a list custom setting is and how it differs from a custom object
- Read a list custom setting's values in Apex without a SOQL query
- Recognize when a list custom setting fits a configuration need
Prerequisites: Module 28: "Apex Security"
What makes a custom setting different from a custom object
Warehouse_Stock__c from Module 23 is a custom object — real transactional data, queried with SOQL, subject to CRUD/field-level security (Module 28). A custom setting is a different kind of custom data structure, purpose-built for configuration: values an admin sets up once and Apex reads repeatedly, cached for fast, cheap access.
Reading a list custom setting
List<Shipping_Rate__c> allRates = Shipping_Rate__c.getAll().values();
for (Shipping_Rate__c rate : allRates) {
System.debug(rate.Name + ': R' + rate.Rate_Per_Kg__c);
}getAll() returns every row of a list custom setting as a Map<String, Shipping_Rate__c> keyed by name — .values() (Module 16) turns that into the List used here. Critically, this is not a SOQL query — it doesn't count against the 100-query governor limit from Module 25, since custom setting data is cached.
When a list custom setting fits
A list custom setting suits static, admin-configured reference data — shipping rates per region, tax rates per country, feature-flag toggles — values that change occasionally through Setup, not through everyday business transactions. It's the wrong choice for data that changes constantly through normal business activity (that's what a real custom object is for).
Exercise
As a comment, explain why reading a list custom setting doesn't count against the SOQL governor limit.
Show hint
Think about how getAll() actually retrieves its data.
List Custom Settings Quiz
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Summary
A list custom setting stores org-wide configuration data as reusable rows — read from cache in Apex, with none of the query-cost or CRUD/FLS considerations a real custom object carries.