System.Reflection.TargetInvocationException: "Expression 'dest => dest' must resolve to top-level member" when configuring AutoMapper profile

Julia Ohorodnichuk 0 Reputation points

I'm encountering an exception when trying to configure AutoMapper in my ASP.NET Core application. The exception message is:

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.ArgumentException: Expression 'dest => dest' must resolve to top-level member and not any child object's properties. You can use ForPath, a custom resolver on the child type or the AfterMap option instead. (Parameter 'lambdaExpression') at AutoMapper.Internal.ReflectionHelper.FindProperty(LambdaExpression lambdaExpression)

Here is my AutoMapper profile configuration:

public class AuthenticationMappingProfile : Profile
        public AuthenticationMappingProfile()
            CreateMap<(RegisterRequest registerRequest, string BaseUrl, byte[] Image), RegisterCommand>()
                .ForPath(dest => dest.BaseUrl, opt => opt.MapFrom(src => src.BaseUrl))
                .ForPath(dest => dest.Avatar, opt => opt.MapFrom(src => src.Image))
                .ForPath(dest => dest.FirstName, opt => opt.MapFrom(src => src.registerRequest.FirstName))
                .ForPath(dest => dest.LastName, opt => opt.MapFrom(src => src.registerRequest.LastName))
                .ForPath(dest => dest.Email, opt => opt.MapFrom(src => src.registerRequest.Email))
                .ForPath(dest => dest.Password, opt => opt.MapFrom(src => src.registerRequest.Password))
                .ForPath(dest => dest.ConfirmPassword, opt => opt.MapFrom(src => src.registerRequest.ConfirmPassword))
                .ForPath(dest => dest.Birthday, opt => opt.MapFrom(src => src.registerRequest.Birthday))
                .ForPath(dest => dest.Gender, opt => opt.MapFrom(src => src.registerRequest.Gender))
                .ForPath(dest => dest.Avatar, opt => opt.MapFrom(src => src.Image));

Here are the related classes:

public record RegisterRequest
        public string FirstName { get; init; }
        public string LastName { get; init; }
        public string Email { get; init; }
        public string Password { get; init; }
        public string ConfirmPassword { get; init; }
        public DateTime Birthday { get; init; }
        public string Gender { get; init; }
        public IFormFile? Avatar { get; init; }

    public record RegisterCommand(
        string FirstName,
        string LastName,
        string Email,
        string Password,
        string ConfirmPassword,
        DateTime Birthday,
        string Gender,
        byte[]? Avatar,
        string BaseUrl
    ) : IRequest<ErrorOr<AuthenticationResult>>;

The exception is thrown during the AutoMapper profile creation. The goal is to map from a tuple (RegisterRequest registerRequest, string BaseUrl, byte[] Image) to RegisterCommand

What I have tried:

Verified the property names and types in the destination and source classes. Checked the AutoMapper documentation for mapping complex types and used .ForPath, ForCtorParam and .ForMember

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