how to update a look up field?

Question

I have two lists.Each list return record with some specific lookup field.

lstCurrentRecord :

(Service__c:{Id=a0G4E000000BDJ6UAO, Name=S-61, Displayed_Code_Label__c=TWZ - TWIZY, Car_Set__c=uma, RecordTypeId=0124E0000004OvhQAE, CurrencyIsoCode=EUR})

lstSelectedRecord :

(Service__c:{ Service__c:{Id=a0G4E000000BrzdUAC, Name=S-134, Displayed_Code_Label__c=92J - LODGY, Car_Set__c=ram, RecordTypeId=0124E0000004OvhQAE, CurrencyIsoCode=EUR})

Here am comparing two lists Displayed_Code_Label__c value.If in lstSelectedRecord does not contains lstCurrentRecord Displayed_Code_Label__c then add that record in one list with lstCurrentRecord carset value. For example

lstCurrentRecord -->Displayed_Code_Label__c=TWZ - TWIZY,     Car_Set__c=uma

lstSelectedRecord --> Displayed_Code_Label__c=92J - LODGY, Car_Set__c=ram,

Now i want to insert Service record as

Displayed_Code_Label__c=92J - LODGY, Car_Set__c=uma. The carset name is changed and inserted as a new record. How to implement this ?

Apex:

public void retrieveService() {
    system.debug('Selected Values >>>>' + strCarsetOption + strNWservice + strCBservice + strOtherservice + strContreOption);
    if (strNWservice == 'true') {
        List < Service__c > lstSNWService = [select id, name, Displayed_Code_Label__c, Car_Set__c from Service__c where Service_Type__c = 'Simple product'
            and Simple_service_type__c = 'Network'
            and Car_Set__c =: strCarsetOption
        ];
        List < Service__c > lstCNWService = [select id, name, Displayed_Code_Label__c, Car_Set__c from Service__c where Service_Type__c = 'Simple product'
            and Simple_service_type__c = 'Network'
            and Car_Set__c =: strCurrentRecId
        ];
        lstService = getUniqueRecords(lstCNWService, lstSNWService);
        upsert lstService;
        system.debug('lstNWService >>>>' + lstService);
    }
}

public List < service__c > getUniqueRecords(List < service__c > lstCurrentRecord, List < service__c > lstSelectedRecord) {
    system.debug('lstCurrentRecord<<<<' + lstCurrentRecord);
    system.debug('lstSelectedRecord <<<<' + lstSelectedRecord);
    mapUniqueService = new map < String, List < Service__c >> ();
    List < Service__c > lstServiceAdd = new List < Service__c > ();
    if (lstCurrentRecord.size() > 0) {
        for (Service__c objService: lstCurrentRecord) {
            mapUniqueService.put(objService.Displayed_Code_Label__c, new List < Service__c > {
                objService
            });
        }
    }
    system.debug('<<<<mapUniqueService' + mapUniqueService);
    if (lstSelectedRecord.size() > 0) {
        for (Service__c objService1: lstSelectedRecord) {
            system.debug('objService1<<<' + objService1);
            if (!mapUniqueService.containsKey(objService1.Displayed_Code_Label__c) && mapUniqueService.size() > 0) {
                system.debug('<<<<objService1 check' + objService1 + mapUniqueService);
                objService1.Car_Set__c = strCurrentRecId;
                lstServiceAdd.add(objService1);
            } else if (mapUniqueService.size() == 0) {
                objService1.Car_Set__c = strCurrentRecId;
                lstServiceAdd.add(objService1);
            }
        }
    }
    system.debug('<<<<lstServiceAdd' + lstServiceAdd);
    return lstServiceAdd;
}

In lstServiceAdd i get the values.Here how to update the carset field which is lookup to service.

Thanks in advance !!

Answer 1

Like you said in your question.

You have two list

lstCurrentRecord -->Displayed_Code_Label__c=TWZ - TWIZY,     Car_Set__c=uma

lstSelectedRecord --> Displayed_Code_Label__c=92J - LODGY, Car_Set__c=ram,

so you can create a map so that map will contain Displayed_Code_Label__c as key and service as record

map<String, Service__c > mapUniqueService = new map<String, Service__c >();

so you can assign the all records i.e. lstCurrentRecord to this map

now check lstSelectedRecord list contain existing Displayed_Code_Label__c values if not then clone that record and change the Car_Set__c value for newly record

List<Service__c> lstServiceAdd = new List<Service__c>();
for(Service__c sObjService: lstSelectedRecord ) { 
    if(!mapUniqueService.containsKey(sObjService.Displayed_Code_Label__c ) ) { 
        Service__c serv = sObjService.clone(); 
        serv.Car_Set__c = strCurrentRecId; 
        lstServiceAdd.add(serv); 
    }
}
insert lstServiceAdd;

Answer 2

Well, you have two lists of same object. For field values in list A you want to search field value from list B element, if it's not exist you want to store element from list B. If I'm right, you should use Set collection instead of Map:

public List <service__c> getUniqueRecords
    (List <service__c> lstCurrentRecord, List <service__c> lstSelectedRecord){

//populate set with unique displayed codes
//string.isblank tells that value is empty or null
set<String> codes = new set<string>();
for (Service__c objService: lstCurrentRecord) {
    if (!string.isblank(objService.Displayed_Code_Label__c)) {
        codes.add(objService.Displayed_Code_Label__c);
    }
}

//for each service in lstSelectedRecord, check if its code is presented in codes
list <Service__c> servicesToUpdate = new list<>(Service__c);

for (Service__c objService: lstSelectedRecord) {
    if (!codes.contains(objService.Displayed_Code_Label__c)){
        //if not presented, update service
        objService.Car_Set__c = strCurrentRecId;
        servicesToUpdate.add(objService);
    }
}

//you can update your records here
//update servicesToUpdate;
return servicesToUpdate;
}

Please become familiar with Collections