Automapper mapping validation during application startup in .net core?

Question

When I was using Automapper v6 (I'm using .net core), I had this command to validate configuration :

   configuration.AssertConfigurationIsValid();

But now, after moving to the latest version, I don't have this since my config is exactly ( docs ):

   private void ConfigureServices(IServiceCollection services)
        {
            services.AddAutoMapper(typeof(AppSettingsMappingProfile));    //marker type    
        }

However, I still want to validate all mappings at startup .

The docs says that I need to do this :

var configuration = new MapperConfiguration(cfg =>
  cfg.CreateMap<Source, Destination>());

configuration.AssertConfigurationIsValid();

But I don't have it since I'm using profiles with this command :

 services.AddAutoMapper(typeof(AppSettingsMappingProfile)); 

Question :

How can I still make AutoMapper scan for validation at startup?

Answer 1

If you look at the source code for AddAutoMapper , you will see that it registers IConfigurationProvider as singleton. This means you can safely have it in your Configure method and do the validation there:

public void Configure(IConfigurationProvider pr)
{
    pr.AssertConfigurationIsValid();
}

Answer 2

Following these steps should work:

1. Add AutoMapper.Extensions.Microsoft.DependencyInjection NuGet package
2. services.AddAutoMapper(typeof(...)) within ConfigureServices(...) .
3. Add IMapper mapper as parameter to Configure(...) method
4. mapper.ConfigurationProvider.AssertConfigurationIsValid(); within Configure(...)

Example (omitting namespace inclusion)

public void ConfigureServices(IServiceCollection services)
{
    services.AddAutoMapper(typeof(Startup));
}

public void Configure(IApplicationBuilder app, IMapper mapper)
{
    mapper.ConfigurationProvider.AssertConfigurationIsValid();
}