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paddingtonpaddington 

Map<ID,ID> without looped SOQL

Hi there,

 

So I think that I kind of understand Maps, in that if you create a map with a SOQL query, such as

 

 

Map<ID,sObject> sObMap = new Map<ID,sObject>([SELECT *fields* FROM sObject WHERE *conditions*]);
 you get the key/value pairing of an sObject ID and the sObject itself. I'm slightly unsure as to the purpose of the *fields* in the SOQL query, but it seems to work where I need it to, namely in specifying an sObject from a list of IDs.
 
Today I was trying to create an <ID,ID> map, so I can take a list of accounts and iterate through them to get a key/value pairing for the IDs of a set of Master-Detail related sObjects (Clent_Form__c). I want to insert a set of a third object (Assessments__c), which has lookups to the Account and the related Client_Form__c. The only way I think I can do this is by putting SOQL in a FOR loop (METHOD 1 below), which I know is bad practice for bulk triggers.
 
Is there a better way of taking a list of Accounts and mapping them to detail sObjects? 
 
Here's the working (messy) class as it stands. 
 
 
public with sharing class createAssessments {

    public static void IEF(List<Account> accs){
        
        //Declare owner ID variable for IEF Assessments queue
        Id ownerId = [Select q.Queue.Id from QueueSobject q where q.Queue.Name = 'Application Screenings' and q.SobjectType = 'Assessment__c'].Queue.Id;
        
        //Create a list of assessments to be inserted
        List<Assessment__c> assessments = new List<Assessment__c> ();

        //METHOD 1 - works but I've got SOQL in a loop
        //Create map of Account ID => Client Form ID
        Map<ID,ID> IEFs = new Map<ID,ID>();
        for (Account a:accs){
            IEFs.put(a.Id,[SELECT Id FROM Client_Form__c WHERE Account__c = :a.Id].Id);
            }
        
        //METHOD 2 - doesn't work as I'm putting sObject Client_Form__c into an ID field when I create the assessments
        //Create list of account IDs for object list accs - is this necessary or could I reference the object list directly? 
        //List<ID> refAccs = new List<ID> ();    
            //for (Account z:accs){
                //refAccs.add(z.Id);
                //}
        //Query client forms for account IDs and put in a map
        //Map<ID,Client_Form__c> IEFs = new Map<ID,Client_Form__c>([SELECT Id, Account__c FROM Client_Form__c WHERE Account__c IN :refAccs]);
              
        //For each account, create two IEF assessments
        for(Account a:accs){
            Assessment__c assess = new Assessment__c();
            assess.Client_Form__c = IEFs.get(a.Id);
            assess.RecordTypeId = '01280000000BR0VAAW';
            assess.OwnerId = ownerId;
            assess.Account__c = a.Id;
            assessments.add(assess);
            assessments.add(assess.clone());
        } 
        //Insert the assessments
        insert assessments;
    }
}

Thanks in advance,
 
Joe 
 
 
 


Best Answer chosen by Admin (Salesforce Developers) 
ShikibuShikibu
Try this. It creates a set from the list of accounts, then queries all the forms that it will need for all of those accounts, then populates the map. 
 
 
Map<Id,Id> accountFormMap = new Map<Id,Id>();
for (Account a: accs) {
    accountFormMap.put(a.Id, null);
}
for (Client_Form__c form : 
            [SELECT ID, Account__c FROM Client_Form__c
             WHERE Account__c in :accountFormMap.keySet()]) {
    accountFormMap.put(Account__c, Id);
}

 
 I find that I frequently need a set of ids from a list of SObjects, so I have created a Utility class, and it contains this method:
 
 
// given a list of SObjects, return a set of ids
public static Set<Id> setOfIdFromListOfSObject ( List<SObject> oList ) {
    Set<Id> Ids = new Set<Id> {};
    for (SObject o : oList) {
        Ids.add( o.id );
    }
    return Ids;
}
 
 Using this utility method, the solution can be expressed more compactly:
 
 
Map<Id,Id> accountFormMap = new Map<Id,Id>();
for (Client_Form__c form : 
            [SELECT ID, Account__c FROM Client_Form__c
             WHERE Account__c in :Utility.setOfIdFromListOfSObject(accs)]) {
    accountFormMap.put(Account__c, Id);
}

 
 
 
 
 
 
 


All Answers
ShikibuShikibu
Try this. It creates a set from the list of accounts, then queries all the forms that it will need for all of those accounts, then populates the map. 
 
 
Map<Id,Id> accountFormMap = new Map<Id,Id>();
for (Account a: accs) {
    accountFormMap.put(a.Id, null);
}
for (Client_Form__c form : 
            [SELECT ID, Account__c FROM Client_Form__c
             WHERE Account__c in :accountFormMap.keySet()]) {
    accountFormMap.put(Account__c, Id);
}

 
 I find that I frequently need a set of ids from a list of SObjects, so I have created a Utility class, and it contains this method:
 
 
// given a list of SObjects, return a set of ids
public static Set<Id> setOfIdFromListOfSObject ( List<SObject> oList ) {
    Set<Id> Ids = new Set<Id> {};
    for (SObject o : oList) {
        Ids.add( o.id );
    }
    return Ids;
}
 
 Using this utility method, the solution can be expressed more compactly:
 
 
Map<Id,Id> accountFormMap = new Map<Id,Id>();
for (Client_Form__c form : 
            [SELECT ID, Account__c FROM Client_Form__c
             WHERE Account__c in :Utility.setOfIdFromListOfSObject(accs)]) {
    accountFormMap.put(Account__c, Id);
}

 
 
 
 
 
 
 
This was selected as the best answer
paddingtonpaddington
Thanks Shikibu. That worked perfectly and I love the Utility class solution. I've been meaning to sort that out for a while, particularly after reading these posts [1, 2] by Steve Andersen at the Salesforce Foundation. For completeness, the final code looks like this:
 
TRIGGER:
 
trigger IEFawaitingAssessment on Account (after update) {

    //Create list of accounts for which the IEF Sub-stage has become awaiting two assessments
    List<Account> ChangedAccounts = new List<Account> ();
    for(Integer i=0; i<Trigger.new.size(); i++){
        if(Trigger.new[i].RecordTypeId == '01280000000BQgyAAG' && Trigger.old[i].Initial_Enquiry_Sub_stage__c != 'Awaiting two assessments' && Trigger.new[i].Initial_Enquiry_Sub_stage__c == 'Awaiting two assessments'){
            ChangedAccounts.add(Trigger.new[i]);
        }
    }
    //Pass this list to the createAssessments class
    Assessments.createIEFfromAccount(ChangedAccounts);
}

 METHOD:
 
public static void createIEFfromAccount(List<Account> accs){
        
        //Declare owner ID variable for IEF Assessments queue
        Id ownerId = [Select q.Queue.Id from QueueSobject q where q.Queue.Name = 'IEF Assessments' and q.SobjectType = 'Assessment__c'].Queue.Id;
        
        //Create a list of assessments to be inserted
        List<Assessment__c> assessments = new List<Assessment__c> ();

        //Call setOfIdFromListOfSObject Utility method to populate a map of account ID to client form ID
        Map<Id,Id> IEFmap = new Map<Id,Id>();       
        for (Client_Form__c form : 
            [SELECT ID, Account__c FROM Client_Form__c
             WHERE RecordTypeId = '01280000000BQlBAAW'
             AND Account__c in :Utility.setOfIdFromListOfSObject(accs)]) {
                IEFmap.put(form.Account__c, form.Id);
        }
              
        //For each account, create two IEF assessments
        for(Account a:accs){
            Assessment__c assess = new Assessment__c();
            assess.Client_Form__c = IEFmap.get(a.Id);
            assess.RecordTypeId = '01280000000BR0VAAW';
            assess.OwnerId = ownerId;
            assess.Account__c = a.Id;
            assessments.add(assess);
            assessments.add(assess.clone());
        } 
        //Insert the assessments
        insert assessments;
    }
 
 
 UTILITY METHOD:
 
//Given a list of SObjects, return a set of ids
    public static Set<Id> setOfIdFromListOfSObject ( List<SObject> oList ) {
        Set<Id> Ids = new Set<Id> {};
        for (SObject o : oList) {
            Ids.add( o.id );
        }
        return Ids;
    }
 
 
 
 


JerryHJerryH
So there's no direct way of retrieving a list of ID's using SOQL without having to do a loop / add?  Why doesn't something as obvious as "List<Id> lstID = new List<Id>([select Id from Account where (some condition)])" work?


ShikibuShikibu
Because apex is derived from Java, not from the more expressive language python!