[SalesForce] Compare Value of One Map with Key of Another Map to create new Map

I have two maps, and am currently using a nested for loop to compare the keys of one map with the values of the other, and then placing the matching info into a new map. Is there a more efficient way to do this without a nested for loop?

            if(groupDefinitionIds.size()>0){
                //Connect the Program Id to the Group Definitions Id (Group Definition Id key, program Id value)
                for(Id assignId: groupAssignmentIds.keyset()){
                    for(Id groupDefId: groupDefinitionIds.keyset()){
                        if(assignId == groupAssignmentIds.get(groupDefId)){
                            groupProgramIds.put(groupDefId, groupAssignmentIds.get(assignId));    
                        }
                    }
                }

Best Answer

Yes, there is.

You can use the containsKey() method of the map class.

if(groupDefinitionIds.size()>0){
    // Iterate over just one of your maps
    for(Id groupDefId: groupDefinitionIds.keyset()){
        // Assuming the keys in both maps are the same, you can simply use
        //   containsKey()
        // By "same keys", I mean that a key from one map can exist in the other.
        // This wouldn't work if, for example, one map held Account Ids, and the
        //   other held Opportunity Ids
        if(groupAssignmentIds.containsKey(groupDefId)){
            groupProgramIds.put(groupDefId, groupAssignmentIds.get(assignId));    
        }
    }
}

There's even a way that you can avoid having any explicit loop at all! (I say "explicit" loop, because the back-end implementation of at least some of the collection class methods probably involves a loop of its own)

// Step 1, clone the map you want to use the values from
Map<Id, MyClass> groupProgramIds = groupAssignmentIds.clone();

// Step 2, keeping/removing keys from a map removes the access to the associated values as well.
// map.keySet().removeAll()/retainAll() does just that
groupProgram.keySet().retainAll(groupDefinitionIds.keySet());

Related Solutions

[SalesForce] get / compare children values on map

The children records will be contained within standard List collections under the parent object record.

Enhancing your much-too-genericized code sample:

Map<Id, Account> AcctOppCustomObjectMap = new Map<Id, Account>([SELECT Id
                                                                    ,(SELECT xxx 
                                                                        FROM xxx__r)
                                                                    ,(SELECT yyy 
                                                                        FROM yyy__r) 
                                                                FROM Account
                                                                WHERE Id IN :idSet]);

List<yyy__c> yThingsToUpdate = new List<yyy__c>();

for (Id accountId : AcctOppCustomObjectMap.keyset()) {
    Account acct = AcctOppCustomObjectMap.get(accountId);

    // the acct reference will have child lists for your subqueries
    // they will not be null, but they could be empty lists
    List<xxx__c> xxxList = acct.xxx__r;
    List<yyy__c> yyyList = acct.yyy__r;

    // iteration of the child records possible now using these two lists
    for (xxx__c xThing : xxxList) {
        for (yyy__c yThing : yyyList) {
            if (xThing.value == yThing.value) {
                // create your relationship and 
                // add to a list for bulk update / insert
                yThingsToUpdate.add(new yyy__c(Id = yThing.Id
                                                   , xxx__c = xThing.Id));

                break; // exit the for loop on the first match if desired
            }
        }
    }
}


if (!yThingsToUpdate.isEmpty()) {
    update yThingsToUpdate;
}

I would probably iterate each child list just once each to create maps of the contents by a desired key so that I could perform a Map.get() instead of repeatedly iterating lists to find the other child record to compare against. Your code sample needs more specific information in it.

Repeated iteration of the yyy list within the xxx list will limit your ability to process records since these will use script statements to iterate and match the records.

[SalesForce] Save a nested query into a Map

UPDATE

If you want to group CaseComment records by Case.AccountId, the following makes more sense:

Map<Id, List<CaseComment>> accountIdToComments = new Map<Id, List<CaseComment>>();
for (CaseComment comment : [
    SELECT Parent.AccountId, Other_Fields__c FROM CaseComment
    WHERE ...
]){
    Id accountId = comment.Case.AccountId;
    if (!accountIdToComments.containsKey(accountId))
        accountIdToComments.put(accountId, new List<CaseComment>());
    accountIdToComments.get(accountId).add(comment);
}

~~You've added the ParentId to your join on CaseComment, but not to your query on Case itself.~~

List<Case> records = [ SELECT (SELECT ParentId, ... FROM CaseComments), ParentId, ... // ^ not on Case object ^ on Case Object FROM Case WHERE ... ];

Note you've confused yourself a bit by naming the collection comments. The collection returned by the query is not a List<CaseComment>. It's a List<Case>.

If you just want to be able to get the List<CaseComment> for a given Case Id, you don't need any for loop at all:

Map<Id, Case> records = new Map<Id, Case>([/*query*/]); // intermediate code ... Case parentCase = records.get(someCaseId); if (parentCase != null) { List<CaseComment> comments = parentCase.CaseComments; // additional processing }

If you're actually trying to group the Case records themselves by their ParentId, then you do indeed need to add that field to your top level SELECT clause:

Map<Id, List<Case>> groupedCases = new Map<Id, List<Case>>(); for (Case record : [/*above query*/]) { if (!groupedCases.containsKey(record.ParentId)) groupedCases.put(record.ParentId, new List<Case>()); groupedCases.get(record.ParentId).add(record); }

Best Answer

Related Solutions

[SalesForce] get / compare children values on map

[SalesForce] Save a nested query into a Map

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