How can I conditionally map properties using Automapper based on user permissions - automapper

Question

I am using Automapper successfully throughout my application however I have come across a particular requirement that I cannot find a solution for.
My application is an ASP.Net Core 3.1 application using Automapper 10. What I need to do is only map some properties from the Dto to the data entity if a user has permission to edit these specific properties. I am using a Claims Principal to store the information I need regarding the user.
In the simplest form I only want to map the property "Enabled" if the user performing the editing is an administrator. I can check if the user is an admin based on claims but I have no idea how I let Automapper know this.
Can it be done or am I better manually map in this instance?
Thanks in advance

Answer 1

One way is to store the user role information in the Items dictionary on runtime. Then using Condition() you can check the role during mapping by retrieving the user role information from the same Items dictionary.
Mapping usage inside a controller:
var entity = mapper.Map<Entity>(dto, opts =>
{
opts.Items["UserRole"] = User.FindFirst(ClaimTypes.Role)?.Value;
});
Mapping configuration:
CreateMap<DTO, Entity>()
.ForMember(
d => d.Enabled,
o =>
{
o.Condition((s, d, sm, dt, resolutionContext) =>
{
return resolutionContext.Items.TryGetValue("UserRole", out var userRole)
&& userRole.ToString() == "Admin";
});
o.MapFrom(s => s.Enabled);
});
Other way is to use ServiceCtor from options inside a ResolutionContext to resolve any services required to establish user role, I will use IHttpContextAccessor as an example:
Mapping usage does not change at all:
var entity = mapper.Map<Entity>(dto);
Mapping configuration a bit more complex:
CreateMap<DTO, Entity>()
.ForMember(
d => d.Enabled,
o =>
{
o.Condition((s, d, sm, dt, resolutionContext) =>
{
var httpContextAccessor = resolutionContext
.Options
.ServiceCtor(typeof(IHttpContextAccessor)) as IHttpContextAccessor;
var userRole = httpContextAccessor
.HttpContext
.User
.FindFirst(ClaimTypes.Role)
?.Value;
return userRole == "Admin";
});
o.MapFrom(s => s.Enabled);
});
Keep in mind that IHttpContextAccessor does not always return a HttpContext. It may be null. It also requires that you register it in ConfigureServices() in your Startup class:
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpContextAccessor();
}