How do you use dependency injection in an asp.net console app? - asp.net

Question

I am doing something like:
private static IServiceProvider serviceProvider;
public Program(IApplicationEnvironment env, IRuntimeEnvironment runtime)
{
var services = new ServiceCollection();
ConfigureServices(services);
serviceProvider = services.BuildServiceProvider();
// Set up configuration sources.
var builder = new ConfigurationBuilder()
.AddJsonFile("appsettings.json")
.AddEnvironmentVariables();
Configuration = builder.Build();
}
public IConfigurationRoot Configuration { get; set; }
private void ConfigureServices(IServiceCollection services)
{
//Console.WriteLine(Configuration["Data:DefaultConnection:ConnectionString"]);
services.AddEntityFramework()
.AddSqlServer()
.AddDbContext<DbContext>(options =>
options.UseSqlServer(Configuration["Data:DefaultConnection:ConnectionString"]));
}
I am struggling to get to use the program using an injected DbContext. Any idea? How do you instantiate the program and get everything injected? I don't know what to do in the static Main method.
Is there an equivalent for this?
public static void Main(string[] args) => WebApplication.Run<Startup>(args);
Something like?
public static void Main(string[] args) => ConsoleApplication.Run<Program>(args);

Answer 1

This is how I did it:
public class Startup
{
public static IConfigurationRoot Configuration { get; set; }
public static void ConfigureServices(IServiceCollection services)
{
services.AddEntityFramework()
.AddSqlServer()
.AddDbContext<DbContext>(options =>
options.UseSqlServer(Configuration["Data:DefaultConnection:ConnectionString"]));
services.AddSingleton<IMyManager, Manager>();
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddSingleton<Program, Program>();
}
public static void Main(string[] args)
{
var services = new ServiceCollection();
var builder = new ConfigurationBuilder()
.AddJsonFile("appsettings.json");
.AddEnvironmentVariables()
.AddUserSecrets();
Configuration = builder.Build();
ConfigureServices(services);
var provider = services.BuildServiceProvider();
CancellationTokenSource ctSource = new CancellationTokenSource();
CancellationToken ct = ctSource.Token;
Task task = Task.Run(async () =>
{
Program program = provider.GetRequiredService<Program>();
await program.Run(ct);
});
try
{
task.Wait();
}
catch (AggregateException e)
{
throw e.InnerException;
}
ctSource.Cancel();
ctSource.Dispose();
}
}
Then the program is just:
class Program
{
private IMyManager _myManager;
public Program(IMyManager myManager)
{
_myManager = myManager;
}
public async Task Run(CancellationToken cancelationToken)
{
while (true)
{
cancelationToken.ThrowIfCancellationRequested();
// My things using _myManager
await Task.Delay(10000, cancelationToken);
}
}
}
I deleted a bunch of stuff for the example so it probably crashes somewhere, but you get the idea.

Answer 2

Just in case anyone else is looking for a small and simple example to follow.
Here is a small console app I wrote recently for a an example. It"s only a small password generator demonstration of DI in an app with unit tests.
https://github.com/AnthonySB/PasswordApplication
using System;
using Microsoft.Extensions.DependencyInjection;
using PasswordExercise.Interfaces;
using PasswordExercise.Services;
namespace PasswordExercise
{
    class Program
    {
        static void Main(string[] args)
        {
            //Dependency injection
            var serviceProvider = new ServiceCollection()
                .AddSingleton<IPasswordGeneratorService, PasswordGenerator>()
                .AddSingleton<IPasswordService, PasswordService>()
                .BuildServiceProvider();
            //Get the required service
            var passwordService = serviceProvider.GetService<IPasswordService>();
            //For reading from the console
            ConsoleKeyInfo key;
            //Display the menu
            passwordService.Menu();
            do
            {
                //Read the console key, do not display on the screen
                key = Console.ReadKey(true);
                switch (key.KeyChar.ToString())
                {
                    case "1":
                        Console.WriteLine("Simple password: {0}", passwordService.SimplePassword());
                        break;
                    case "2":
                        Console.WriteLine("Moderate password: {0}", passwordService.ModeratePassword());
                        break;
                    case "3":
                        Console.WriteLine("Strong password: {0}", passwordService.StrongPassword());
                        break;
                }
            } while (key.Key != ConsoleKey.Escape);
        }
    }
}
Hope this helps someone.