Using Factory Pattern with ASP.NET Core Dependency Injection

Question

I need the ASP.Net Core dependency injection to pass some parameters to the constructor of my GlobalRepository class which implements the ICardPaymentRepository interface.

The parameters are for configuration and come from the config file and the database, and I don't want my class to go and reference the database and config itself.

I think the factory pattern is the best way to do this but I can't figure out the best way to use a factory class which itself has dependencies on config and database.

My startup looks like this currently:

public class Startup {     public IConfiguration _configuration { get; }     public IHostingEnvironment _environment { get; }      public Startup(IConfiguration configuration, IHostingEnvironment environment)     {         _configuration = configuration;         _environment = environment;     }      public void ConfigureServices(IServiceCollection services)     {         services.AddScoped<IDbRepository, DbRepository>();         var connection = _configuration.GetConnectionString("DbConnection");         services.Configure<ConnectionStrings>(_configuration.GetSection("ConnectionStrings"));         services.AddDbContext<DbContext>(options => options.UseSqlServer(connection));         services.AddScoped<ICardPaymentRepository, GlobalRepository>();         ...     }      public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IRFDbRepository rFDbRepository)     {      ...     } } 

The GlobalRepository constructor looks like this:

public GlobalRepository(string mode, string apiKey) { } 

How do I now pass the mode from configuration and the apiKey from the DbRepository into the constructor from Startup?

Answer 1

Use the factory delegate overload when registering the repository

//...  string mode = "get value from config";  services.AddScoped<ICardPaymentRepository, GlobalRepository>(sp => {             IDbRepository repo = sp.GetRequiredService<IDbRepository>();     string apiKey = repo.GetApiKeyMethodHere();      return new GlobalRepository(mode, apiKey); });  //... 

Alternative using ActivatorUtilities.CreateInstance

//...  string mode = "get value from config";  services.AddScoped<ICardPaymentRepository>(sp => {             IDbRepository repo = sp.GetRequiredService<IDbRepository>();     string apiKey = repo.GetApiKeyMethodHere();      return ActivatorUtilities.CreateInstance<GlobalRepository>(sp, mode, apiKey); });  //...