Mapping multiple source fields to a Multi-line textbox target field

Question

I'm trying to map multiple address fields from my source (i.e. address 1, City, State, Zip) into a target field which is a multi-line textbox.

I'm using the OOTB "Collection to String Value" reader as the Source Value Transformer within the address mapping.

However, it appears my delimiter of \r\n is being encoded somehow, so instead of line breaks i get

Address1\r\n\City\r\nState\r\nZip

Any way I can map multiple fields into separate lines in a multi-line textbox?

I probably need to write my own reader to transform the value - but I wanted to check if there was a better way first.

I'm also going through the framework code - and i don't see where the value is actually encoded - so i'm concerned if i DO write a custom value reader my value will just end up encoded as well - so i think i need to find that FIRST so i know how to avoid it

For example, The ootb value reader is only this

public virtual ReadResult Read(object source, DataAccessContext context)
{
  if (source == null)
    return ReadResult.PositiveResult((object) null, DateTime.Now);
  ICollection collection = source as ICollection;
  if (collection == null)
    return ReadResult.NegativeResult(DateTime.Now);
  List<object> objectList = new List<object>();
  foreach (object obj in (IEnumerable) collection)
    objectList.Add(obj);
  return ReadResult.PositiveResult((object) string.Join<object>(this.Separator, (IEnumerable<object>) objectList), DateTime.Now);
}

So it seems that simply writing my own value reader to add line breaks is pointless as unless I figure out how to avoid the encoding.

UPDATE -Solution from Vlad below was it. Below is the updated converter in case it helps others.

protected override ConvertResult<IValueReader> ConvertSupportedItem(ItemModel source)
{
    return this.PositiveResult((IValueReader)new CollectionToStringValueReader()
    {
            Separator = PreserveLineBreaks(this.GetStringValue(source, FieldNameSeparator))
    });
 }

private string PreserveLineBreaks(string separator)
{
    var unescapedSeparator = Regex.Unescape(separator);

    return unescapedSeparator == Environment.NewLine ? unescapedSeparator : separator;
}

Answer 1

When converter gets separator value from field its value is "\\r\\n" and at the end your result is "Address1\r\n\City\r\nState\r\nZip".

Just add your custom converter.

    [SupportedIds("[YOUR TEMPLATE ID]")]
public class CollectionToStringNewLIneConverter : BaseItemModelConverter<IValueReader>
{
    public CollectionToStringNewLIneConverter(IItemModelRepository repository) : base(repository)
    {
    }
    protected override ConvertResult<IValueReader> ConvertSupportedItem(ItemModel source)
    {
        var reader = new CollectionToStringValueReader
        {
            Separator = Environment.NewLine
        };
        return PositiveResult(reader);
    }
}

Or still use the same template with Separator field but with custom converter to enescape separator value.

[SupportedIds("{03639AB3-5C4B-45E3-AE4E-A41EF33F3E06}")]
public class CustomUnescapeCollectionToStringValueReaderConverter : BaseItemModelConverter<IValueReader>
{
    public const string FieldNameSeparator = "Separator";
    public CustomUnescapeCollectionToStringValueReaderConverter(IItemModelRepository repository) : base(repository)
    {
    }
    protected override ConvertResult<IValueReader> ConvertSupportedItem(ItemModel source)
    {
        var reader = new CollectionToStringValueReader
        {
            Separator = Regex.Unescape(this.GetStringValue(source, FieldNameSeparator))
        };
        return PositiveResult(reader);
    }
}