Read e-mail addresses from appsettings.json and write in a List

Question

Unfortunately, I can't manage to load the email addresses in the appsettings.json to the list . What am I doing wrong?

IConfiguration config = new ConfigurationBuilder()
                    .AddJsonFile("appsettings.json", false, true)
                    .Build();

Setting settings = config.GetRequiredSection("Settings").Get<Setting>();

Config Class:

public class Setting
{
   public List<MailAddress> MailAddresses { get; set; }
}

Shortened appsettings.json:

{
  "Settings": {
    "Mailadresses": [
      [ "first@domain.com", "DisplayName 1" ],
      [ "second@domain.com, DisplayName 2" ],
      [ "third@domain.com, DisplayName 3" ]
    ]
  }
}

Thanks in advance for your help.

Shouldn't it be `[ {}, {} ]` and not `[ [], [] ]` ? You deserialize it to `List` and not `List`. Try changing it to: `"Mailadresses": [{ "EmailAddress": "first@domain.com", "DisplayName": "DisplayName 1" }, ... ]` — Fabjan, Mar 01 '23 at 10:36
@Fabjan: Thank you, I have changed it. Unfortunately, the list remains empty, so it is not the solution. List MailAddresses is null — ThoDan, Mar 01 '23 at 11:25

score 1 · Accepted Answer · answered Mar 01 '23 at 13:21

Here is a complete example which creates appsettings.json followed by reading the data. Written in .NET Core 7.

using Microsoft.Extensions.Configuration;
using System.Text.Json;

namespace StackDemo;

internal partial class Program
{
    static void Main(string[] args)
    {

        CreateAppSettings();

        IConfigurationRoot config = InitMainConfiguration();
        List<Mailaddress> addresses = 
            config.GetSection($"{nameof(Settings)}:{nameof(Mailaddress)}")
                .Get<Mailaddress[]>().ToList();

        foreach (var address in addresses)
        {
            Console.WriteLine($"{address.Display,-20}{address.Address}");
        }

        Console.ReadLine();

    }

    private static void CreateAppSettings()
    {
        List<Mailaddress> addresses = new List<Mailaddress>()
        {
            new () { Address = "first@domain.com", Display = "First" },
            new () { Address = "second@domain.com", Display = "Second" },
            new () { Address = "third@domain.com", Display = "Third" }
        };

        Root setting = new Root() 
        { 
            Settings = new Settings()
            {
                MailAddress = addresses.ToArray()
            }
        };

        string jsonString = JsonSerializer.Serialize(setting, 
            new JsonSerializerOptions { WriteIndented = true });
        File.WriteAllText("appsettings.json", jsonString);
    }

    private static IConfigurationRoot InitMainConfiguration()
    {

        var builder = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile("appsettings.json");

        return builder.Build();

    }
}

#region Place each class in their own file
public class Root
{
    public Settings Settings { get; set; }
}

public class Settings
{
    public Mailaddress[] MailAddress { get; set; }
}

public class Mailaddress
{
    public string Address { get; set; }
    public string Display { get; set; }
} 
#endregion

Read e-mail addresses from appsettings.json and write in a List

1 Answers1