CODEWITHSUNDEEP
c#asp.net-mvcautomapper
tickwave
tickwave

Reputation: 3443

Mapping string to List<string> and vice versa using Automapper

Basically I have this class which represents 1:1 with my database

public class User
{
    public int UserID { get; set; }
    public string Username { get; set; }
    public string Role { get; set; }
}

and I have this viewmodel

public class UserEditViewModel
{
    public UserEditViewModel()
    {
        Roles = new List<string>();
    }

    public int UserID { get; set; }
    [Required]
    public string Username { get; set; }
    [Required]
    public List<string> Roles { get; set; }
}

I have no idea how to map between these 2. My current setup :

Mapper.CreateMap<UserEditViewModel, User>().ReverseMap();

Upvotes: 8

Views: 17578

Answers (4)

Soroush Borhan
Soroush Borhan

Reputation: 63

To map a string to a collection Cihan Uygun's answer works, only to fix the error

CS0854 An expression tree may not contain a call or invocation that uses optional arguments

which is caused in later updates you should Replace src.Role.Split(',') with src.Role.Split(',', System.StringSplitOptions.None) or src.Role.Split(',', System.StringSplitOptions.RemoveEmptyEntries)

To do the reverse mapping just use src => string.Join(',', src.Roles)

Source for the error fix: https://newbedev.com/mapping-string-to-list-string-and-vice-versa-using-automapper

Upvotes: 4

Cihan Uygun
Cihan Uygun

Reputation: 2138

There is something similar to your questiong here, please can you check this out AutoMapper: Collection to Single string Property

PS: This is an example for mapping collection to single string property probably your example should look like below;

Mapper.CreateMap<User, UserEditViewModel>()
    .ForMember(dest => dest.Roles,
    m => m.MapFrom(src => src.Role.Split(',').ToList()));

And mapping the instances like below;

User myUser = new User();
myUser.Role = "r1,r2,r3,r4,r5";
myUser.UserID = 1;
myUser.Username = "MyUserName";

UserEditViewModel result = Mapper.Map<UserEditViewModel>(myUser);

enter image description here

2020 Edit: Since Expression.Call API does not support optional parameter and you should Replace src.Role.Split(',') with src.Role.Split(',', System.StringSplitOptions.None) or src.Role.Split(',', System.StringSplitOptions.RemoveEmptyEntries)

Upvotes: 12

erikscandola
erikscandola

Reputation: 2936

If you want to concatenate all values in your list of string you need to use string.Join. In mapper you need to use ForMember method.

From UserEditViewModel to User:

Mapper.CreateMap<User, UserEditViewModel>().ForMember(user => user.Role, opt => opt.MapFrom(userEdit => string.Join(", ", userEdit.Roles)));

From User to UserEditViewModel:

Mapper.CreateMap<UserEditViewModel, User>().ForMember(userEdit => userEdit.Roles, opt => opt.MapFrom(user => user.Role.Split(",").ToList()));

Upvotes: 1

spersson
spersson

Reputation: 550

I think you should be able to use the AutoMapper AfterMap, something like this:

.AfterMap((src,dest) => dest.Roles.Add(src.Role))

Credit to the answer here: Map a property to a collection item

Upvotes: 0

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