[SalesForce] JSON from nested query

As @eyescream and @Sdry stated you should do some preprocessing to build up a Set/List of Ids to supply to your SOQL query. You can create maps that can then be used after bulk queries are done. These sort of bulk patterns of building up a collection of Ids for a SOQL query is extremely common in Apex.

This shows using the LoanInfo and assumes that the EquipmentID will be unique in the batch.

Map<Id, LoanInfo> equipmentToLoanInfo = new Map<Id, LoanInfo>();
Set<Id> loanedToIds = new Set<Id>();
for(LoanInfo LI : LoanInfos)
{      
    // Map Equipment ID to Loan Info.
    // Will use keySet() in query later
    equipmentToLoanInfo.put(LI.EquipmentID, LI);

    // store off all of the Ids for later queries
    loanedToIds.add(LI.LoanedTo);
}

Map<Id, User> dbUsers = new Map<Id, User>([
    Select <a bunch of fields> 
    From User 
    Where Id In :loanedToIds
]);
// create Same type of maps for other LoanedTo types...

for(Equipment_Loan__c objELOld : [
    select <a bunch of fields> 
    from Equipment_Loan__c 
    where Equipment__c In :LI.equipmentToLoanInfo.keySet() and Actual_Return_Date__c=null
])
{  
     LoanInfo equipLoanInfo = equipmentToLoanInfo.get(objELOld.Equipment__c);
     if (equipLoanInfo.LoanType == 'User') {
         dbUser = dbUsers.get(equipLoanInfo.LoanedTo);
         // set the fields...

     } else if (equipLoanInfo.LoanType == 'Contact') {
         // same as user, but with contact
     } // continue with other types...
}

If all that you are doing is using the SF Data Loader on the Equipment_Loan__c and all that you need to do is hookup values on a trigger (e.g., before insert, etc.) then you can change the above to use a Map of Equipment_Loan__c records instead of LoanInfo, e.g.,:

Map<Id, Equipment_Loan__c> equipmentToLoanInfo = Trigger.NewMap;
Set<Id> loanedToIds = new Set<Id>();
for(Id eId : equipmentToLoanInfo.keySet())
{      
    Equipment_Loan__c equipLoan = equipmentToLoanInfo.get(eId);

    // store off all of the Ids for later queries
    loanedToIds.add(equipLoan.LoanedTo);
}

// Basically the same code as when using Map<Id, LoanInfo>, 
// but change to use Equipment_Loan__c

The other type of situation that you can run into is where you may need to map a one to many. For example, if your LoanInfos within the same batch could share an EquipmentID, you might want to use processing such as the following.

Map<Id, List<LoanInfo>> equipmentToLoanInfos = new Map<Id, List<LoanInfo>>();
for (LoanInfo LI : LoanInfos) {
    if (equipmentToLoanInfos.get(LI.EquipmentID) == null) {
       equipmentToLoanInfos.put(LI.EquipmentID, new List<LoanInfo>());
    }
    equipmentToLoanInfos.get(LI.EquipmentID).add(LI);
}

The Apex development team changed the behavior of the JSON serialization in response to several customer issues.

As you are aware, we will typically version changes to the system behavior where possible, in order to protect backward compatibility. There are situations in which we do not version behavior, however. We made an assumption that JSON parsers would not have an issue not receiving null values, since the information received is not relevant. It's like the junk mail you reflexively throw out when sifting through your mail.

As per your post, it's clear that some parsing strategies depend on null values being included in the JSON output. We apologize that our assumption was incorrect, and that your integration and others were unable to operate with the new version.

We have undone the change for the Spring '13 release. To support the original customer cases that prompted these changes, we will version in the originally intended fix in the Summer release.

Thanks,

Josh Kaplan

Product Manager, Apex Code