Why does SOQL return related records when run directly but not when run with Apex?

Question

I have a SOQL query that looks like this:

SELECT Id, OwnerId, IsDeleted, AboutThirtyFieldsTotal__c, ...
(SELECT Id, IsDeleted, OverFiftyFields__c, ...
 FROM Borrowers__r )
FROM Loan__c WHERE LSC__c = '0051F00000ocJMdQAM'
ORDER BY CreatedDate LIMIT 200

The entire query is about 1,500 characters long.

When I run this query directly (by selecting it in VS Code and executing it with the command pallet) I get the correct result, with columns for Borrowers__r.FirstName__c with multiple rows for each of the related records.

If I run the exact same query from within Database.query, I don't get the related data, only the data from Loan__c with no data after the last field in the outer SELECT?

Why do I get related data when I directly execute the SOQL but not when it's executed by Apex?

Answer 1

When you debug an SObject record, the output is not necessarily going to show you everything in memory, as it coerces the complex data type into a String to render.

What you observe when you system.debug(someRecord) in this case is incomplete. If you were to system.debug(someRecord.Parent__r.Field__c, you would see these fields are in fact populated.

Alternatively, you can system.debug(JSON.serialize(someRecord)) and see a more complete representation.