How to extract a list from appsettings.json in .net core

Question

I have an appsettings.json file which looks like this:

{
    \"someSetting\": {
        \"subSettings\": [
            \"one\",
            \"two\",
                 


        

Answer 1

In .NetCore this is what I did:

Normal Setup:

In your appsettings.json create a configuration section for your custom definitions:

    "IDP": [
    {
      "Server": "asdfsd",
      "Authority": "asdfasd",
      "Audience": "asdfadf"
    },
    {
      "Server": "aaaaaa",
      "Authority": "aaaaaa",
      "Audience": "aaaa"
    }
  ]

Create a class to model the objects:

public class IDP
{
    public String Server { get; set; }
    public String Authority { get; set; }
    public String Audience { get; set; }

}

in your Startup -> ConfigureServices

services.Configure>(Configuration.GetSection("IDP"));

Note: if you need to immediately access your list within your ConfigureServices method you can use...

var subSettings = Configuration.GetSection("IDP").Get>();

Then in your controller something like this:

Public class AccountController: Controller
{
    private readonly IOptions> _IDPs;
    public AccountController(IOptions> IDPs)
    {
        _IDPs = IDPs;
    }
  ...
}

just as an example I used it elsewhere in the above controller like this:

       _IDPs.Value.ForEach(x => {
            // do something with x
        });

Edge Case

In the case that you need multiple configs but they can't be in an array and you have no idea how many sub-settings you will have at any one time. Use the following method.

appsettings.json

"IDP": {
    "0": {
      "Description": "idp01_test",
      "IDPServer": "https://intapi.somedomain.com/testing/idp01/v1.0",
      "IDPClient": "someapi",
      "Format": "IDP"
    },
    "1": {
      "Description": "idpb2c_test",
      "IDPServer": "https://intapi.somedomain.com/testing/idpb2c",
      "IDPClient": "api1",
      "Format": "IDP"
    },
    "2": {
      "Description": "MyApp",
      "Instance": "https://sts.windows.net/",
      "ClientId": "https://somedomain.com/12345678-5191-1111-bcdf-782d958de2b3",
      "Domain": "somedomain.com",
      "TenantId": "87654321-a10f-499f-9b5f-6de6ef439787",
      "Format": "AzureAD"
    }
  }

Model

public class IDP
{
    public String Description { get; set; }
    public String IDPServer { get; set; }
    public String IDPClient { get; set; }
    public String Format { get; set; }
    public String Instance { get; set; }
    public String ClientId { get; set; }
    public String Domain { get; set; }
    public String TenantId { get; set; }
}

Create Extension for Expando Object

public static class ExpandObjectExtension
    {
        public static TObject ToObject(this IDictionary someSource, BindingFlags bindingFlags = BindingFlags.Instance | BindingFlags.Public)
               where TObject : class, new()
        {
            Contract.Requires(someSource != null);
            TObject targetObject = new TObject();
            Type targetObjectType = typeof(TObject);

            // Go through all bound target object type properties...
            foreach (PropertyInfo property in
                        targetObjectType.GetProperties(bindingFlags))
            {
                // ...and check that both the target type property name and its type matches
                // its counterpart in the ExpandoObject
                if (someSource.ContainsKey(property.Name)
                    && property.PropertyType == someSource[property.Name].GetType())
                {
                    property.SetValue(targetObject, someSource[property.Name]);
                }
            }

            return targetObject;
        }
    }

ConfigureServices

var subSettings = Configuration.GetSection("IDP").Get>();

var idx = 0;
foreach (var pair in subSettings)
{

    IDP scheme = ((ExpandoObject)pair).ToObject();
    if (scheme.Format == "AzureAD")
    {
        // this is why I couldn't use an array, AddProtecedWebApi requires a path to a config section
        var section = $"IDP:{idx.ToString()}";
        services.AddProtectedWebApi(Configuration, section, scheme.Description);
        // ... do more stuff
        
    }
    idx++;
}