I am trying to serialize and deserialize a class (say A) into Json.
The class has multiple properties (say X1, X2, X3) which are object instances (of class X) which contains large lists.

public class A
{
    public X X1 { get; set; }

    public X X2 { get; set; }

    public X X3 { get; set; }
}

public class X
{
    public List<Y> LargeList { get; set; }
}

public class Y
{
    public List<object> AnotherList { get; set; }
}

public class Temp
{
    public static void JsonTest()
    {
        A a = new()
        {
            X1 = new()
            {
                LargeList =
                [
                    new()
                    {
                        AnotherList = ["placeholder"]
                    }
                ]
            },
            X2 = new()
            {
                LargeList =
                [
                    new()
                    {
                        AnotherList = ["dummy"]
                    }
                ]
            },
            X3 = new()
            {
                LargeList =
                [
                    new()
                    {
                        AnotherList = ["text"]
                    }
                ]
            }
        };
        JsonSerializerOptions options = new() { WriteIndented = true };
        Debug.WriteLine(JsonSerializer.Serialize(a, options));
    }
}

While I can serialize those instances (of class X) individually and load them into my main class (A), I need a way to serialize class A into Json in such a way that its properties (X1, X2, …) are serialized into relative file paths (“X1.json”, “X2.json”, …) only when needed.

For example: This is the normal output

{
  "X1": {
    "LargeList": [
      {
        "AnotherList": [
          "placeholder"
        ]
      }
    ]
  },
  "X2": {
    "LargeList": [
      {
        "AnotherList": [
          "dummy"
        ]
      }
    ]
  },
  "X3": {
    "LargeList": [
      {
        "AnotherList": [
          "text"
        ]
      }
    ]
  }
}

What I need is something like this:

{
  "X1": "X1.json",
  "X2": "X2.json",
  "X3": "X3.json",
  "SplitJson": true
}

I need to control the serialization by means of a Boolean property in class A called SplitJson. If enabled the serializer should serialize some specified properties (with an attribute) into relative paths. Then those individual instances of X of those properties should be serialized into the corresponding files. This should also work with deserialization.

Also, are there any ways to implement delayed (or async) setting of properties? I need the class A to load first but the properties should not be deserialized until required. But the relative paths to the separate Jsons should be stored somewhere and must deserialize when needed.