What is the Correct collection class structure to hold SOQL subquery results?

Question

I've got a scenario where a status field on the parent object needs to be updated to reflect the status of the most recently created child object. To solve this, I've done a SOQL with a subquery :-

Select Id, CRA_Status__c, (Select Id, Status__c, CreatedDate from CRAs__r order by CreatedDate DESC LIMIT 1) from Client__c

but what is the correct combination of Collection classes to house it? I suspect a list of wrapper classes is the only way, but happy to get suggestions from people

Answer 1

You don't need any helper classes at all. You can just iterate through the results and update the parents accordingly. In this case the "correct" structure is the one you find easiest to write and test. But it doesn't have to be any more complicated than the below:

List<Parent__c> toUpdate = new List<Parent__c>();
for (Parent__c parent : [
    SELECT
        CRA_Status__c, (
            SELECT Status__c, CreatedDate FROM Children__r
            ORDER BY CreatedDate DESC LIMIT 1
        )
    FROM Parent__c WHERE ...
]){
    if (!parent.Children__r.isEmpty() && parent.CRA_Status__c != children[0].Status__c)
        toUpdate.add(new Parent__c(CRA_Status__c=children[0].Status__c));
}
update toUpdate;