I wouldn't normally ask this kind of question on here, but unfortunately whilst AutoMapper seems to be a good mapping library, its documentation is woefully bad - there is no XML documentation for the library's methods, and the most official online documentation I could find was this, which is very brisk. If anyone has any better documentation, please let me know.
That said, here's the question: why use Mapper.Initialize? It doesn't seem to be required as you can just use Mapper.CreateMap immediately, and as there is no documentation I have no clue what Initialize is meant to do.
I asked on the AutoMapper users list, and this answer basically says why:
https://groups.google.com/forum/?fromgroups=#!topic/automapper-users/0RgIjrKi28U
It's something to do with allowing AutoMapper to do deterministic (stochastic) optimization. Performance-wise, it's better to get all your mappings created in the Initialize call.
The initialization runs all the map creation once so it is then done when you come to do your mapping. You can create a map whenever you want, but this will slow your code down as the mapping creation involves reflection.
I find it best to use profiles for my mapping code and use something like the following to get this all setup:
public class AutoMapperConfiguration : IRequiresConfigurationOnStartUp
{
private readonly IContainer _container;
public AutoMapperConfiguration(IContainer container)
{
_container = container;
}
public void Configure()
{
Mapper.Initialize(x => GetAutoMapperConfiguration(Mapper.Configuration));
}
private void GetAutoMapperConfiguration(IConfiguration configuration)
{
var profiles = GetProfiles();
foreach (var profile in profiles)
{
configuration.AddProfile(_container.GetInstance(profile) as Profile);
}
}
private static IEnumerable<Type> GetProfiles()
{
return typeof(AutoMapperConfiguration).Assembly.GetTypes()
.Where(type => !type.IsAbstract && typeof(Profile).IsAssignableFrom(type));
}
}
