How to read appsettings.json in my _layout.chtml - razor

Question

I cannot seem to figure out how to read values from the appsettings.json in my _Layout.chtml file.
Is it not just available, something like this?
#Configuration["ApplicationInsights:InstrumentationKey"]
I created a new MVC project using razor pages.
fyi, i'm an mvc newbee - code samples help a lot.

Answer 1

In .net core mvc you can inject the configuration by adding the following two lines at the top of your view:
#using Microsoft.Extensions.Configuration
#inject IConfiguration Configuration
You can then access the value like this:
#Configuration.GetSection("ApplicationInsights")["InstrumentationKey"]

Answer 2

If you use the options pattern you can inject them into your view like this:
#using Microsoft.Extensions.Options
#inject IOptions<ApplicationInsightsOptions>
ApplicationInsightsOptionsAccessor
#
{
var instrumentationKey =
ApplicationInsightsOptionsAccessor.Value.InstrumentationKey;
}
Options pattern in ASP.NET Core

Answer 3

Using ActionFilters you can interrupt the request and add the configuration variables maybe to the ViewBag so it becomes accessible from the views or from the _Layout.cshtml File.
For example, if the following configuration section is inside your appsettings.json
{
"MyConfig": {
"MyValue": "abc-def"
}
}
In the code MyConfig.cs would be:
public class MyConfig
{
public string MyValue{ get; set; }
}
First create a very simple ActionFilter which derives from IAsyncActionFilter as following :
public class SampleActionFilter : IAsyncActionFilter
{
private MyConfig _options;
public SampleActionFilter(IConfiguration configuration)
{
_options = new MyConfig();
configuration.Bind(_options);
}
public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
{
((Microsoft.AspNetCore.Mvc.Controller)context.Controller).ViewBag.MyConfig = _options;
await next();
}
}
Later in the Startup.ConfigureServices method change services.AddMvc to the following:
public void ConfigureServices(IServiceCollection services)
{
//..........
services.AddMvc(options=>
{
options.Filters.Add(new SampleActionFilter(
Configuration.GetSection("MyConfig")
));
});
//..........
}
To access the values just simply in the _Layout.cshtml or other view you can type:
#ViewBag.MyConfig.MyValue