I'm creating a service that requires some config parameters and a logger. Here is the constructor for my service:
public StorageProvider(string directory, ILogger<StorageProvider> logger)
I just added the logger. I used to initalize it like this in my startup.cs:
services.AddSingleton<IStorageProvider>(
new StorageProvider(Configuration["TempStorage.Path"]));
The directory parameter comes from the config file, and the logger gets DI'ed. How do I setup my IStorageProvider?
You should do the following:
TempStorage:Path into its own configuration class, e.g. StorageProviderSettings.StorageProvider depend upon that new configuration class.Example:
public sealed class StorageProviderSettings
{
public readonly string TempStoragePath;
public StorageProviderSettings(string tempStoragePath)
{
if (string.IsNullOrWhiteSpace(tempStoragePath))
throw new ArgumentException(nameof(tempStoragePath));
this.TempStoragePath = tempStoragePath;
}
}
public sealed class StorageProvider : IStorageProvider
{
public StorageProvider(
StorageProviderSettings settings, ILogger<StorageProvider> logger)
{
// ...
}
}
// Registration
services.AddSingleton(new StorageProviderSettings(Configuration["TempStorage.Path"]));
services.AddSingleton<IStorageProvider, StorageProvider>();
Use the Options pattern as Tratcher suggests in a comment. Read more in the official docs on Configuration.
Basically you define a class to be hold the value you need:
public class StorageProviderOptions
{
public string TempStoragePath { get; set; }
}
Then in ConfigureServices you register the type:
services.Configure<StorageProviderOptions>();
In your code, you request IOptions<StorageProviderOptions> and set this to an instance of StorageProviderOptions:
public class SomeController
{
private readonly StorageProviderOptions _options;
public SomeController(IOptions<StorageProviderOptions> options)
{
_options = options.Value;
}
}
Finally, make sure you have an element in your configuration source that matches the TempStoragePath name. Alternately, you can register the option in ConfigureServices using code:
services.Configure<ServiceProviderOptions>(o => o.TempStoragePath = "temp");
ILogger? Is that also a singleton? If so, pass that same instance to theILoggerregistration to theStorageProviderconstruction.IOptions<StorageProviderOptions>to inject the directory path.ILogger<StorageProvider>does not need an actual instance ofStorageProvider, if that's what you're thinking. The type param is for distinguishing log entries, it doesn't actually do anything with it.