How to navigate multiple lists/maps and turn into string

Question

I'm trying to populate a text field on Account with the Territory names of the account on insert or update (original territories, not Enterprise Territories or Territories2).

I've mapped through Account to Account Share to Group to Territory and have the correct territories but I can't seem to connect it back to the Account again.

Due to the AccountShare list inside the first map I am getting Incompatible key type List for Map at line 75 where I try to populate AccountTerritories__c (the text field on Account) with the correct territories. I tried vastly simplifying line 75 to just MapofTerritories.values(); (which I don't think would bulk at all) and got the error of Illegal assignment from List to String at line 75.

How can I get the correct territories linked with the correct Account ID and entered into the Text field?

Thank you for your help

trigger AccountTerritories on Account(before update) {
    if (Trigger.isBefore) {
        Set < Id > setOfAccountIds = new Set < Id > ();

        for (Account acct: Trigger.New) {
            if (Trigger.isUpdate) {
                if (acct.Id != null) {
                    setOfAccountIds.add(acct.Id);
                }
            }
        }

        if (setOfAccountIds.size() > 0) {

            /* Declaration of collection data types */
            Map < id, List < AccountShare >> MapOfAccountShare = new Map < id, List < AccountShare >> ();
            Map < Id, Id > mapOfGroup = new Map < Id, Id > ();
            Map < Id, String > mapOfTerritories = new Map < Id, String > ();


            //Query in Account Share object
            /*
            Those Accounts which are assigned via Territory Assignment Rules.
            You can query those Accounts by filtering RowCause = 'Territory' in AccountShare object query.
            */
            List < AccountShare > listOfAccountShare = [Select Id, UserOrGroupId, AccountId, RowCause from AccountShare where AccountId IN: setOfAccountIds];
            System.debug('=== contents of listOfAccountShare: ' + listOfAccountShare);
            System.debug('=== size of listOfAccountShare: ' + listOfAccountShare.size());
            List < Id > Groupids = new List < Id > ();
            for (AccountShare a: listofAccountShare) {
                Groupids.add(a.UserOrGroupId);
            }

            //Map of Account Share

            for (AccountShare acctShare: listOfAccountShare) {
                if (MapOfAccountShare.containsKey(acctShare.AccountID)) {
                    MapOfAccountShare.get(acctShare.AccountID).add(acctShare);
                } else {
                    MapOfAccountShare.put(acctShare.AccountID, new List < AccountShare > {
                        acctShare
                    });
                }
            }
            System.debug('=== all AccountShare keys in the map: ' + mapOfAccountShare.keySet());
            System.debug('=== all AccountShare values in the map (as a List): ' + mapOfAccountShare.values());
            System.debug('=== size of mapOfAccountShare: ' + mapOfAccountShare.size());

            //Query in Group object            
            List < Group > listOfGroup = [Select Id, RelatedId from Group where Type = 'Territory'
                and Id IN: GroupIDs
            ];
            System.debug('=== contents of listOfGroup: ' + listOfGroup);
            System.debug('=== size of listOfGroup: ' + listOfGroup.size());
            //Map of Group object
            for (Group groupRecord: listOfGroup) {
                mapOfGroup.put(groupRecord.Id, groupRecord.RelatedId);
            }
            System.debug('=== all Group keys in the map: ' + mapOfGroup.keySet());
            System.debug('=== all Group values in the map (as a List): ' + mapOfGroup.values());
            System.debug('=== size of MapOfGroup: ' + mapOfGroup.size());

            //Query in Territory object
            List < Territory > listOfTerritory = [Select Id, Name from Territory where Id IN: mapOfGroup.Values()];
            System.debug('=== contents of listOfTerritories: ' + listOfTerritory);
            System.debug('=== size of listOfTerritories: ' + listOfTerritory.size());
            //Map of Territory object

            for (Territory Territories: listOfTerritory) {
                mapOfTerritories.put(Territories.Id, Territories.Name);
                System.debug('=== all Territories keys in the map: ' + mapOfTerritories.keySet());
                System.debug('=== all Territories values in the map (as a List): ' + mapOfTerritories.values());
                System.debug('=== size of MapOfTerritories: ' + mapOfTerritories.size());
            }

            for (Account updatedAccount: Trigger.new) {
                String territory = MapofTerritories.values().get(mapofGroup.get(mapofAccountShare.get(updatedaccount.id)));
                updatedAccount.territories = territory;
            }

        }

    }
}

Answer 1

You have the below line inside of a for loop:

mapOfTerritories.put(Territories.Id, Territories.Name);

If you want a list of the Territory Names, you can just use

mapOfTerritories.values()

and assign that to a list.

You could also have created the list inside the original for loop where you created the map by simply doing something like this:

        list<string>terrlst = new list<string();

        for (Territory Territories: listOfTerritory) {
            mapOfTerritories.put(Territories.Id, Territories.Name);
            terrlst.add(Territories.Name);
            System.debug('=== all Territories keys in the map: ' + mapOfTerritories.keySet());
            System.debug('=== all Territories values in the map (as a List): ' + mapOfTerritories.values());
            System.debug('=== size of MapOfTerritories: ' + mapOfTerritories.size());
        }

Answer 2

Finally figured out how to get it mapped properly. Here's what I ended up with at the end to map back to the beginning and put in the Territory names.

for (Account updatedAccount : Trigger.new) {
        List<AccountShare> accountSharesList = mapofAccountShare.get(updatedaccount.id);

        // Start with empty string of territories
        String territories = '';
        for (AccountShare accountshare : accountshareslist){ //loop through accountShares
          // Get the group from the share
          id groupid = accountshare.userorgroupid;
          // Get the territory from the group map
          id territoryid  = mapofGroup.get(groupid);
          // Get the Territory Name from the territory Map
          string TerritoryName = MapofTerritories.get(territoryid);
          if(territoryname != null){
               // Add next territory name to string of territories
               territories = territories + territoryName +', ';// this is how i add the new territory to my string of territories
          }
        }
        // remove last two chars here, but only if territories is not empty string
        if(String.isNotBlank(territories)){
            String TerritoryNames = Territories.Substring(0,Territories.length()-2);
            updatedAccount.territories__c = TerritoryNames;
            }