Dynamic dependency injection .NET Core WebAPI

It is being a long time after my last blog post here. I already moved to .NET Core from .NET Framework almost two years ago. And I must say it has been made my life easier. Well I can say I am intrigued with in build dependency injection. Recently I got a requirement that needs two different implementations for single interface.

Classes : ProcessExcelFiles.cs
               ProcessCsvFiles.cs

Interface : IFileUploadContentProcess.cs

Purpose of this two classes are process uploaded xlsx file or csv file.

	public interface IFileUploadContentProcess
	{
	IEnumerable<StoreOrder> ProcessUploads(IFormFile file);
	}
	public class ProcessExcelFiles : IFileUploadContentProcess
	{
	public IEnumerable<StoreOrder> ProcessUploads(IFormFile file)
	{
	throw new NotImplementedException();
	}
	}
	public class ProcessCsvFiles : IFileUploadContentProcess
	{
	public IEnumerable<StoreOrder> ProcessUploads(IFormFile file)
	{
	throw new NotImplementedException();
	}
	}

view raw IFileUploadContentProcess.cs hosted with ❤ by GitHub

First register class files as your desired way.

Then use a lambda function to parameterize interfaces to implementation register.

	public void ConfigureServices(IServiceCollection services)
	{
	services.AddControllers();
	services.AddTransient<IStoreOrderService, StoreOrderService>();
	services.AddTransient<ProcessExcelFiles>();
	services.AddTransient<ProcessCsvFiles>();
	// Add resolvers for different sources here
	services.AddTransient<Func<string, IFileUploadContentProcess>>(serviceProvider => key =>
	{
	return key switch
	{
	"xlsx" => serviceProvider.GetService<ProcessExcelFiles>(),
	_ => serviceProvider.GetService<ProcessCsvFiles>(),
	};
	});
	}

view raw startup.cs hosted with ❤ by GitHub

How to use:

	public class StoreOrderService : IStoreOrderService
	{
	private readonly Func<string, IFileUploadContentProcess> _fileUploadContentProcess;
	public StoreOrderService(Func<string, IFileUploadContentProcess> fileUploadContentProcess)
	{
	_fileUploadContentProcess = fileUploadContentProcess;
	}
	public async Task<IEnumerable<StoreOrder>> UploadStoreOrdersAsync(IFormFile file)
	{
	//// passing csv to process csv type(default), if xlsx, pass xlsx
	var records = _fileUploadContentProcess("csv").ProcessUploads(file);
	return records;
	}
	}

view raw StoreOrderService.cs hosted with ❤ by GitHub