C# AutoMapper map list to flatten object based on condition

[Rajgan _10]

My Question Stack Overflow

I want to know how I can achieve the following mapping via Automapper.

public class MyTestClass
{
  public int BrandId;
  public decimal? Amount;
  public string Currency;
  public List<MyMappingClass> MappingClassList;
}

public class MyMappingClass
{
  public string RefNumber;
  public int TransRef;
}

public class MyDestDBClass
{
  public int BrandId;
  public decimal? Amount;
  public string Currency;
  public string RefNumber;
  public int TransRef;
}

I have written the following logic were I am looking to populate Amount & currency for 1st Item. The Second Item should have null Amount & currency.

C# Code:

var inputObj = new MyMappingClass()
{
   BrandId = 1,
   Amount = 10.00,
   Currency = "USD",
   MappingClassList = new List<MyMappingClass>()
                       {
                         new MyMappingClass(){ RefNumber = "S123", TransRef = "4567" },
                         new MyMappingClass(){ RefNumber = "S1234", TransRef = "45679" },
                        }

};
var isFirstItem = true;
var dbObjList = new List<MyDestDBClass>();

inputObj.MappingClassList.ForEach(x=> 
{
      var outObj = new MyDestDBClass()
            {
                 BrandId = inputObj.BrandId ,
                 RefNumber = x.RefNumber,
                 TransRef = x.TransRef,
                 Amount =  isFirstItem ? inputObj.Amount : null,
                 Currency = isFirstItem ? inputObj.Currency: null,
            };
        dbObjList.Add(outObj);
        isFirstItem = false;    
  });

I tried Automappers ConstructProjectionUsing Where I was able to loop through and create a list but unable to apply the first item check in the mapping config.

I expect the following output:

    dbObjList  = List<MyDestDBClass>()
    {
     new MyDestDBClass() {BrandId = 1 ,RefNumber = S123,TransRef = 4567,Amount = 10.00 , Currency = "USD" },
 new MyDestDBClass() {BrandId = 1 ,RefNumber = S123,TransRef = 4567,Amount = null , Currency = null }
    }