How to run non-static code that uses dependency injection in .net core

Question

I created a new console app in VS2017 and I am trying to run this code to demonstrate I can encrypt and decrypt strings in .NET Core. I have tried calling RunSample from the Program.cs Main but it wants it to be a static method. If I make RunSample static then I'm getting a null reference exception when trying to set the var protectedpayload.

using System;
using Microsoft.AspNetCore.DataProtection;

public class MyClass
{
    private readonly IDataProtector _protector;

    public MyClass(IDataProtectionProvider provider)
    {
        _protector = provider.CreateProtector("Contoso.MyClass.v1");
    }

    public void RunSample()
    {
        Console.WriteLine("Enter input:");
        string input = Console.ReadLine();

        var protectedPayLoad = _protector.Protect(input);
        Console.WriteLine($"Protect returned: {protectedPayLoad}");

        var unprotectedPayLoad = _protector.Unprotect(protectedPayLoad);
        Console.WriteLine($"Unprotect returned: {unprotectedPayLoad}");
    }
}

How can I run it?

UPDATE: Trying to run it from Program.cs, I have the following but .MyClass has a "cannot resolve" syntax error / red underline on it.

using System;

namespace encrypttest
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
            new Program().MyClass.RunSample();
        }
    }
}

UPDATE 2:

I created my app by going to new project, .NET Core and then Console App (.NET Core):

UPDATE 3: I've changed my code as suggested but have the following error:

UPDATE 4: I've removed the using as suggested, but now I get:

You need an instance of the class to run it. Show us how you are calling this from the main method — maccettura
– maccettura, Commented Jul 10, 2018 at 16:51
Where is the dependency injection here? I suspect you're not creating (or injecting) this class at all. — DavidG
– DavidG, Commented Jul 10, 2018 at 16:55
OK, you don't have dependency injection here at all, why did you think you did? — DavidG
– DavidG, Commented Jul 10, 2018 at 16:57

lex.xu · Accepted Answer · 2018-07-10 17:34:13Z

2

you need DI your IDataProtector in Program.cs

class Program
{
    static void Main(string[] args)
    {
        ServiceCollection services = new ServiceCollection();

        services.AddScoped<IDataProtector>();
        services.AddScoped<MyClass>();

        using (var serviceProvider = services.BuildServiceProvider())
        {
            var service = serviceProvider.GetService<MyClass>();
            service.RunSample();
        }
    }
}

update - 1:

Install from NuGet

Install-Package Microsoft.Extensions.DependencyInjection

update - 2:

remove using like this

var serviceProvider = services.BuildServiceProvider()
var service = serviceProvider.GetService<MyClass>();
service.RunSample();

update - 3:

My code is DI example... you need change like this

ServiceCollection services = new ServiceCollection();

services.AddDataProtection();
services.AddScoped<MyClass>();

var serviceProvider = services.BuildServiceProvider();
var service = serviceProvider.GetService<MyClass>();
service.RunSample();

Install from NuGet

Install-Package Microsoft.AspNetCore.DataProtection

edited Jul 10, 2018 at 17:34

answered Jul 10, 2018 at 17:07

lex.xu

1993 bronze badges

Sign up to request clarification or add additional context in comments.

9 Comments

egmfrs Over a year ago

I'm missing a using for ServiceCollection?

lex.xu Over a year ago

Install-Package Microsoft.Extensions.DependencyInjection

egmfrs Over a year ago

I've updated my question with the error this is now giving me. See the final image

lex.xu Over a year ago

remove using, because you MyClass not inherit IDisposable

egmfrs Over a year ago

OK, I've got another problem - see update to question.

|

Chris Pratt · Accepted Answer · 2018-07-10 17:59:48Z

1

The complaint about making RunSamples static is because you're not newing up the class that defines it. If it's not an instance, then the method must be static to access it. However, since the class (and method) has a dependency that needs to be satisfied, you cannot make it static. Simply, you need to use dependency injection to create an instance of your class with its dependency satisfied in order to call the RunSamples method.

To use dependency injection in a console app, it's as simple as adding the Microsoft.Extensions.DependencyInjection NuGet package, and then:

var services = new ServiceCollection()
    .BuildServiceProvider();

However, that's not very useful as you haven't registered anything, so just do all that before calling BuildServiceProvider:

var serviceProvider = new ServiceCollection()
    .AddDataProtection()
    .AddScoped<MyClass>()
    .BuildServiceProvider();

Since you want to utilize data protection, you'll obviously need the Microsoft.AspNetCore.DataProtection NuGet as well.

Then, when you want an instance of MyClass:

using (var scope = serviceProvider.CreateScope())
{
    var myClass = scope.GetRequiredService<MyClass>();
    myClass.RunSamples();
}

answered Jul 10, 2018 at 17:59

Chris Pratt

240k37 gold badges414 silver badges469 bronze badges

2 Comments

egmfrs Over a year ago

Thanks for your help. My using of Microsoft.AspNetCore.DataProtection is grey and saying it is not required by the code, however .AddDataProtection is underlined red.

egmfrs Over a year ago

"ServiceCollection does not contain a definition for AddDataProtection" is the error

popsiporkkanaa · Accepted Answer · 2018-07-10 17:04:42Z

0

I guess this is what you are missing (from this link: https://learn.microsoft.com/en-us/aspnet/core/security/data-protection/using-data-protection?view=aspnetcore-2.1)

public static void Main(string[] args)
{
    // add data protection services
    var serviceCollection = new ServiceCollection();
    serviceCollection.AddDataProtection();
    var services = serviceCollection.BuildServiceProvider();

    // create an instance of MyClass using the service provider
    var instance = ActivatorUtilities.CreateInstance<MyClass>(services);
    instance.RunSample();
}

You have to initiate an instance of IDataProtectionProvider by calling ActivatorUtilities.CreateInstance

answered Jul 10, 2018 at 17:04

popsiporkkanaa

7781 gold badge9 silver badges17 bronze badges

2 Comments

egmfrs Over a year ago

ServiceCollection and ActivatorUtilities are underlined in red - what usings am I missing?

egmfrs Over a year ago

I added using Microsoft.Extensions.DependencyInjection; but now I get syntax error on .AddDataProtection - Sevice Collection does not contain a definition for it.

Collectives™ on Stack Overflow

How to run non-static code that uses dependency injection in .net core

3 Answers 3

9 Comments

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

9 Comments

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related