Dependency injection, inject with parameters

Question

I\'m using vNext implementation of DI. How to pass parameters to constructor? For example, i have class:

public class RedisCacheProvider : ICacheProvider
{
         


        

Answer 1

You can either provide a delegate to manually instantiate your cache provider or directly provide an instance:

services.AddSingleton<ICacheProvider>(provider => new RedisCacheProvider("myPrettyLocalhost:6379"));

services.AddSingleton<ICacheProvider>(new RedisCacheProvider("myPrettyLocalhost:6379"));

Please note that the container will not explicitly dispose of manually instantiated types, even if they implement IDisposable. See the ASP.NET Core doc about Disposal of Services for more info.

Answer 2

You can use like below. Tried to explain with an example.

Manager class.

public class Manager : IManager
{
    ILogger _logger;
    IFactory _factory;
    public Manager(IFactory factory, ILogger<Manager> logger)
    {
        _logger = logger;
        _factory = factory;
    }
}

Startup.cs class

        public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<IFactory, Factory>(sp =>
        {
            var logger = sp.GetRequiredService<ILogger<Factory>>();
            var dbContext = sp.GetRequiredService<MyDBContext>();
            return new Factory(dbContext, logger);
        });
        services.AddTransient<IManager, Manager>(sp =>
        {
            var factory = sp.GetRequiredService<IFactory>();
            var logger = sp.GetRequiredService<ILogger<Manager>>();
            return new Manager(factory, logger);
        });
    }

You can read full example here.

DI in Startup.cs in .Net Core

Answer 3

A bit late to the party, but you could DI inject a factory that creates and exposes an instance of your provider class.

Answer 4

You can use :

 services.AddSingleton<ICacheProvider>(x =>
      ActivatorUtilities.CreateInstance<RedisCacheProvider>(x, "myPrettyLocalhost:6379"));

Dependency Injection : ActivatorUtilities will inject any dependencies to your class.

Answer 5

If the constructur also has dependencies that should be resolved by DI you can use that:

public class RedisCacheProvider : ICacheProvider
{
    private readonly string _connectionString;
    private readonly IMyInterface _myImplementation;

    public RedisCacheProvider(string connectionString, IMyInterface myImplementation)
    {
        _connectionString = connectionString;
        _myImplementation = myImplementation;
    }
    //interface methods implementation...
}

Startup.cs:

services.AddSingleton<IMyInterface, MyInterface>();
services.AddSingleton<ICacheProvider>(provider => 
    RedisCacheProvider("myPrettyLocalhost:6379", provider.GetService<IMyInterface>()));