public static IEnumerable <string> GetAvailableProviders(this DbMigrationsConfiguration configuration)
{
// Marcus Miris @ 19/Out/2016:
// ... tudo isso apenas para basicamente retornar a string "System.Data.SqlClient" sem hardcode...
// Explicando: o Entity Framework tem vários Dependencies Resolvers internos para resolver
// diversas questões. Uma delas são os providers registrados. Os providers podem ser registrados
// [1] no AppConfig; [2] no DbMigrationConfiguration; [3] No DbConfiguration.
// O código abaixo varre todos os resolvers do Entity Framework à procura dos providers.
var defaultProviders = from resolver in configuration.GetDependencyResolver().GetInternalResolvers()
where resolver is SingletonDependencyResolver <Func <MigrationSqlGenerator> >
let keyPredicate = resolver.GetPrivateField <Func <object, bool> >(@"_keyPredicate")
select keyPredicate.Target.GetPrivateFieldValue("key") as string;
// retorna também os providers que foram registrados pelo caller.
var customProviders = from keyValuePair in configuration.GetPrivateField <Dictionary <string, MigrationSqlGenerator> >("_sqlGenerators")
select keyValuePair.Key;
return(defaultProviders
.Union(customProviders)
.DefaultIfEmpty("System.Data.SqlClient"));
}
/// <summary>
/// Recupera o <see cref="IDbDependencyResolver"/> utilizado
/// pelo <see cref="DbMigrationsConfiguration"/> informado.
/// </summary>
private static IDbDependencyResolver GetDependencyResolver(this DbMigrationsConfiguration configuration)
=> configuration.GetPrivateField <Lazy <IDbDependencyResolver> >("_resolver")?.Value;