Handling Nullable Reference Types in C# 10 with Entity Framework Core - implementing AutoMapper Configuration
I just started working with I'm trying to figure out I'm currently working on a project using C# 10 and Entity Framework Core 6.0, and I've run into an scenario while trying to map entities to DTOs with AutoMapper... My entities include several nullable reference types, and I'm getting a `NullReferenceException` when the mapping occurs, specifically when properties expected to be non-nullable are being accessed. Here’s a simplified version of my entity and DTO: ```csharp public class UserEntity { public int Id { get; set; } public string? FirstName { get; set; } public string? LastName { get; set; } } public class UserDto { public int Id { get; set; } public string FirstName { get; set; } // This is non-nullable public string LastName { get; set; } // This is also non-nullable } ``` My AutoMapper configuration looks like this: ```csharp var config = new MapperConfiguration(cfg => { cfg.CreateMap<UserEntity, UserDto>() .ForMember(dest => dest.FirstName, opt => opt.MapFrom(src => src.FirstName ?? "DefaultFirstName")) .ForMember(dest => dest.LastName, opt => opt.MapFrom(src => src.LastName ?? "DefaultLastName")); }); ``` Despite the null checks I’ve implemented in the mapping configuration, I'm still working with the `NullReferenceException` when the mapping runs. After debugging, I discovered that the source entity sometimes does not have a `FirstName` or `LastName` set, which leads to problems when AutoMapper tries to access them directly. I’ve also tried using `Optional<T>` from `System.Collections.Generic` for handling these properties, but that didn't solve the scenario. Could it be that my configuration is incorrect for handling nullable types? How can I effectively map these properties without running into null reference issues, while keeping my DTOs as non-nullable? Any insights or recommendations would be greatly appreciated! Has anyone else encountered this? This is for a desktop app running on macOS. Any advice would be much appreciated. I've been using C# for about a year now. Is this even possible?