Fix DML inside a loop

Debug it · Intermediate · 15 min · Runs in your Salesforce Developer org · Apex Path

Scenario. Sales loads the quarter's Opportunities from a spreadsheet, about 180 at a time. The load fails with Too many DML statements: 151.

An Opportunity trigger creates a follow-up Task per record with insert inside the loop. It fails at 151 records. Collect first, insert once.

What you will learn

Every insert, update or delete statement counts against the limit of 150 per transaction. insert task; in a loop over 200 Opportunities is 200 statements. Salesforce stops at Too many DML statements: 151.

One statement saves up to 10,000 records, so build a list in the loop and save it once:

for (Opportunity opp : opportunities) {
    followUps.add(new Task(WhatId = opp.Id));
}
insert followUps;

Gotcha. Guard the insert with isEmpty().

The task

Fix the handler so it saves all follow-up Tasks with one insert, however many Opportunities were created.

Examples:

Opportunity Big deal → one Task, Subject Follow up: Big deal, linked to the Opportunity
3 Opportunities → 3 Tasks, each linked to its own Opportunity
200 Opportunities → 200 Tasks, one DML statement

Requirements:

Build each Task in the loop with Subject Follow up: followed by the Opportunity Name, and WhatId set to the Opportunity Id.
Add each Task to a list instead of inserting it.
Insert the list once, after the loop, only when it is not empty.
Keep the Task fields exactly as they are.

Starter code

public class AS_37B5DFEF8A27_FollowUpTasks {
    public static void afterInsert(List<Opportunity> opportunities) {
        for (Opportunity opportunity : opportunities) {
            Task followUp = new Task(
                Subject = 'Follow up: ' + opportunity.Name,
                WhatId = opportunity.Id
            );
            insert followUp;
        }
    }
}

When it passes

Every new Opportunity gets one follow-up Task, and the trigger spends one DML statement whether it handles 1 Opportunity or 200.

Try this drill free

You write the Apex yourself. ApexSensei runs it and tells you what passed and what did not.

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