I'm trying to use Microsoft's "hosting/logging/configuration/dependency injection" thing for a new console app in .Net 5.0. A little background first: I'm totally new to all that, and I have never used any of the similar stuff that's apparently long been available in ASP.NET (in fact I don't think I've ever even used ASP.NET at all, and if I did, it was long long ago, and in a very small way). With that said:
I feel like I'm missing something regarding configuration, specifically with binding a section of appsettings.json (or whatever) to an options class. Let's say I have a preexisting class -- not specifically intended for use with Microsoft's DI/etc. framework -- that takes some sort of options class in its constructor:
public X(XOptions options) {
this.Blah = options.OneThirtySeventhBlah * 37;
}
I found various examples of how to get stuff from appsettings.json into my code:
services.Configure<XOptions>(options => hostContext.Configuration.GetSection("X").Bind(options));
But upon running with that, I found (to my surprise) that it wouldn't work with my preexisting X class. To get it to work, I also had to change X's constructor (or, I guess, at least add a new constructor) to take an IOptions<XOptions> instead of simply taking an XOptions:
public X(IOptions<XOptions> options) {
this.Blah = options.Value.OneThirtySeventhBlah * 37;
}
That works fine and all, but... am I missing something here? Do I really have to change my pre-existing class (which, again, is not specifically for use in this type of framework) to have all this additional Microsoft stuff as a dependency?
I suppose I could instead write a MicrosoftifiedX class, taking an IOptions<XOptions> in its constructor and implementing the same interface as X does, and make that part of an optional package, but... like I said, I feel like I'm missing something. Can I really not just bind the configuration directly to XOptions? If I can, how?
And if I can't, then I can't help but imagine that there might be some standard (or at least reasonably widespread) framework/pattern/library for dealing with this that's less tedious than my MicrosoftifiedX idea. Does anyone know of such a thing? Thanks.
Yes you can and, in my opinion you should, prevent from letting your line-of-business classes take a dependency on IOption<T>. Instead, register the options object as singleton:
XOptions xoptions = config.GetSection("SectionName").Get<XOptions>();
// Verify XOptions here (if required)
// Register XOptions as singleton
services.AddSingleton<XOptions>(xoptions);
services.AddTransient<IX, X>(); // X takes a dependency on XOptions