Automapper mapping string to List<string>

Question

I have two classes

 public class SourceClass
{
    public Guid Id { get; set; }
    public string Provider { get; set; }
}


public class DestinationClass
{
    public Guid Id { get; set; }
    public List<string> Provider { get; set; }
}

I've initialized my mapping by using the following code

CreateMap<SourceClass, DestinationClass>();

And then in my controller, I have :

Mapper.Map<List<DestinationClass>>(requests)

where "requests" is a List of SourceClass objects being passed in to my controller.

My question is, how can I map the Provider(of type string) in my SourceClass to Provider(of type List in my Destination class?

The provider in sourceclass will always be a single string, and provider in the destination class will always be a list of a single string.

Here is what I've tried in the mapping configurations:

CreateMap<SourceClass, DestinationClass>().ForMember(destinationMember => destinationMember.Provider,
                memberOptions => memberOptions.MapFrom(src => {
                return string.IsNullOrEmpty(src.Provider) ? [""] : src.Provider.ToList());

Can you describe in English how the string maps to a list of strings? Does it become a list containing that single string? — user47589
– user47589, Commented Mar 5, 2020 at 21:41
@Amy correct, so if the string in my source class was "Test", it should be ["Test"] in my destination class. — blazerix
– blazerix, Commented Mar 5, 2020 at 21:42
@TylerHundley I'm not exactly sure how to go about doing this, so I've tried using .ForMember and the ternary operator but not able to understand why it isn't working. — blazerix
– blazerix, Commented Mar 5, 2020 at 21:43
If the string is null or empty, its an empty list? Or is it a null list? Or does the list contain the empty string? — user47589
– user47589, Commented Mar 5, 2020 at 21:46

Tyler Hundley · Accepted Answer · 2020-03-05 21:51:27Z

2

First off I'd recommend renaming your destination property to Providers to avoid confusion/represent that it is a collection. Then you could give this a try

CreateMap<SourceClass, DestinationClass>()
  .ForMember(destinationMember => destinationMember.Providers,
  memberOptions => memberOptions.MapFrom(src => new List<string> {src.Provider ?? ""}));

Specifically this bit

src => new List<string> {src.Provider ?? ""}

Creates a new list of type string with one value, either src.Provider, or if that is null, an empty string.

answered Mar 5, 2020 at 21:51

Tyler Hundley

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Comments

claudiom248 · Accepted Answer · 2020-03-05 22:07:23Z

0

If you cast your source member's Provider property to a List, you would get a List of char type. This code should reflect what you need.

CreateMap<SourceClass, DestinationClass>()
.ForMember(
    destinationMember => destinationMember.Provider,
    memberOptions => memberOptions.MapFrom(
        src => string.IsNullOrEmpty(src.Provider) ? new List<string>() { "" } : new List<string> { src.Provider }
    )
);

answered Mar 5, 2020 at 22:07

claudiom248

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Comments

Tyler Hundley · Accepted Answer · 2020-03-05 22:51:19Z

0

Replace your mapping configuration with this one:

CreateMap<SourceClass, DestinationClass>()
  .ForMember(destinationMember => destinationMember.Provider,
  memberOptions => memberOptions
    .MapFrom(src => 
    { 
      return new List<string>{ string.IsNullOrEmpty(src.Provider) ? "" : src.Provider)
    });

edited Mar 5, 2020 at 22:51

Tyler Hundley

8976 silver badges12 bronze badges

answered Mar 5, 2020 at 21:51

Ako Javakhishvili

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1 Comment

user47589 Over a year ago

Multiple lines of code should be formatted using triple backticks or by prefixing each line with four spaces. Single backticks are for inline code.

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