如何将空的 object 从 appsettings.json 加载到字典中？

Question

I'm trying to load values into a custom options class on app startup in C#/.net6. Some of the input from appsettings.json is not being loaded as I would like.

My options class looks like this:

    public class CustomOptions
    {
        
        public Dictionary<string, CustomInfo> MyOptions { get; set; }
        
    }

    public class CustomInfo
    {

        public Dictionary<string, string> DictionaryField { get; set; } = new Dictionary<string, string>();

        public List<string> ListField { get; set; } = new List<string>();
    }

and appsettings.json contains the following:

"CustomOptions" : {
    "MyOptions": {
      "OptionOne": {},
      "OptionTwo": {
        "DictionaryField": {
          "ValueOne": "somevalue",
          "ValueTwo": "someothervalue"
        },
        "ListField": [
          "ListItem"
        ]
      }
    }
  }

and loading the options in Program.cs with

builder.Services.AddOptions<EndpointOptions>().Bind(builder.Configuration.GetSection(EndpointOptions.Key));

As it stands, OptionTwo is loaded correctly with all fields set, yet OptionOne does not even appear in the injected IOptions<TOptions> service.

What I would like is for OptionOne to be loaded into the MyOptions dict with a default CustomInfo object or null value. Is this possible?

Edit: I need to be able to add more options beyond OptionOne and OptionTwo at some point, and ideally would be able to do this through appsettings.json , hence the need for a dictionary in MyOptions class. All these options will still follow the CustomInfo class.

Answer 1

The JsonConfigurationFileParser ignores any empty object and simply add value of null as configuration value, that is ignored during binding .

If you really need both options to be added to the dictionary, you could add at least one property to OptionOne section:

"OptionOne": {
  "DictionaryField": {}
}

Frankly, in the sense of low memory allocating, it makes sense to not create an empty instance of CustomInfo , but use the TryGetValue method on dictionary to test if the value exists.

Answer 2

the easiest way is to use this code

CustomOptions customOptions = configuration.GetSection("CustomOptions").Get<CustomOptions>();

var myOptions = customOptions.MyOptions;

classes

public class CustomOptions
{
    public MyOptions MyOptions { get; set; }
}

public class MyOptions
{
    public CustomInfo OptionOne { get; set; }
    public OptionTwo OptionTwo { get; set; }
}
public class CustomInfo
{

    public Dictionary<string, string> DictionaryField { get; set; } = new Dictionary<string, string>();

    public List<string> ListField { get; set; } = new List<string>();
}

public class DictionaryField
{
    public string ValueOne { get; set; }
    public string ValueTwo { get; set; }
}

public class OptionTwo
{
    public DictionaryField DictionaryField { get; set; }
    public List<string> ListField { get; set; }
}