如何将 appsettings.json 设置与设置名称中的点绑定

Question

After watching/reading some tutorials about the option pattern in .net for binding your settings to a c# model, I had this particular question about binding the setting “Microsoft.Hosting.Lifetime” to a model.

Situation I know how to bind settings to a model via the option pattern. So having the appsettings.json file like

"FeatureFlags": {
    "IsFeature1Enabled": "false",
    "IsFeature2Enabled": "false",
    "IsFeature3Enabled": "true"
  }

would result in code like:

model:

public class FeatureFlagOptions
{
    public bool IsFeature1Enabled { get; set; } = false;
    public bool IsFeature2Enabled { get; set; } = false;
    public bool IsFeature3Enabled { get; set; } = false;
}

startup.cs:

private void SetUpAppSettingsModels(IServiceCollection services)
{
    services.Configure<FeatureFlagOptions>(options => Configuration.GetSection("FeatureFlags").Bind(options));
}

class with DI:

private readonly FeatureFlagOptions _featureFlags;
public ClassNameHere(IOptions<FeatureFlagOptions> featureFlags)
{
    _featureFlags = featureFlags.Value;
}

Question

If you start a new web application and choose for example a web api, the standard appsettings will contain the appsetting “Microsoft.Hosting.Lifetime”. Like in the picture in the beginning. So how should I implement that setting in my model?

I Googled a lot, searched on stackoverflow and even my favorite blog writer Rick Strahl ( https://weblog.west-wind.com/posts/2017/dec/12/easy-configuration-binding-in-aspnet-core-revisited ) skipped the part with the logging section. I hope someone can help me with this one. Thanks!

Why do I want that property?: because reasons;)

Answer 1

Thanks to Asawyer, we came to a solution. Maybe there is a better one, but for now we fixed it as follows:

Model:

public class LoggingModel
{
    public LogLevel LogLevel { get; set; }
}

public class LogLevel
{
    public string Default { get; set; }
    public string Microsoft { get; set; }

    //[JsonProperty("Microsoft.Hosting.Lifetime")] => Did not work :(
    public string MicrosoftHostingLifetime { get; set; }
}

startup.cs:

services.Configure<LoggingModel>(options => Configuration.GetSection("Logging").Bind(options));
services.Configure<LoggingModel>(options =>
{
     options.LogLevel.MicrosoftHostingLifetime = Configuration["Logging:LogLevel:Microsoft.Hosting.Lifetime"];
});

class with DI:

private readonly LoggingModel _loggingModel;
public ClassNameHere(IOptions<LoggingModel> loggingOptions)
{
    _loggingModel= loggingOptions.Value;
}

Answer 2

In .NET 6, the ConfigurationKeyNameAttribute has been added to support this

Answer 3

In a similar situation, I used a less strongly typed solution, as the idea to read the specific settings in Startup.cs did not feel like a clean solution.

Here's my appsettings.json:

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  }
}

And to read the "Logging.LogLevel" section I used a Dictionary instead

public class Logging
{
    public const string Default = "Default";
    public const string Microsoft = "Microsoft";
    public const string Microsoft_Hosting_Lifetime = "Microsoft.Hosting.Lifetime";

    public Dictionary<string, string> LogLevel { get; set; }
}

and to use this dictionary<string, string> while pretending that it's keys are not free style strings

var logLevels = loggingOptions.Value.LogLevel;
var logLevels_Default = logLevels[Logging.Default];
var logLevels_Microsoft = logLevels[Logging.Microsoft];
var logLevels_Microsoft_Hosting_Lifetime = logLevels[Logging.Microsoft_Hosting_Lifetime];