Updating a dependency injected singleton

Question

I generate a singleton at runtime

public void ConfigureServices(IServiceCollection services)
{
    var applications = Utils.generateApplications()
    services.AddSingleton<ApplicationModel[]>(applications);
    services.AddMvc();
}

How can I later update this dependency injected ApplicationModel[] with a completely new ApplicationModel[]. I have a feature in my application that the user can use to trigger a data refresh on the applications, but how can I update the underlying injected Singleton so all future injections will use the updated applications? I have a function Utils.generateApplications() that gets an up to date list of applications and returns a ApplicationModel[]. How do I overwrite the old injected Singleton with a new object to be injected into future calls if that makes sense?

I have some code :

public void UpdateData()
{
    var applications = Utils.generateApplications()
    //How do I set applications to replace the injected singleton for all future injections?
}

Answer 1

I wouldn't monkey with dependency injection that way. Instead, inject a factory, and write whatever logic you need to return the proper instance.

Simple factory:

interface IApplicationModelFactory
{
    ApplicationModel[] Model { get; }
}

class ApplicationModelFactory : IApplicationModelFactory
{
    public ApplicationModel[] Model { get; set; }
}

Registration:

services.AddSingleton<IApplicationModelFactory>
(
    new ApplicationModelFactory[] { Model = util.generateApplications() }
)

class receiving the injection:

class Foo
{
    protected readonly IApplicationModelFactory _factory;

    public Foo(IApplicationModelFactory injected)
    {
        _factory = injected;
    }

    protected ApplicationModel[] => _factory.Model;

    public void Bar()
    {
        DoSomethingWithModel(this.ApplicationModel);
    }
}