CustomSerializeProperty

Program.cs

using System;
using System.Diagnostics.CodeAnalysis;
using System.Text.Json;
using System.Text.Json.Serialization;

var person = new Person("Alberto", "JobInfo", new JobInfo("CSF", "Software Architect"));

var serializeOptions = new JsonSerializerOptions();
serializeOptions.Converters.Add(new BaseInfoConverter());

var firstJson = JsonSerializer.Serialize(person, serializeOptions);
var secondJson = JsonSerializer.Serialize(person with { InfoDescription = "ParentsInfo", OtherInfo = new ParentsInfo("Silvina", "José") }, serializeOptions);

Console.WriteLine(firstJson);
Console.WriteLine(secondJson);

Console.WriteLine("\n#########################################\n");

var firstPerson = JsonSerializer.Deserialize<Person>(firstJson, serializeOptions);
Console.WriteLine(firstPerson);
Console.WriteLine(firstPerson.OtherInfo is JobInfo);
Console.WriteLine(firstPerson.OtherInfo is ParentsInfo);

var secondPerson = JsonSerializer.Deserialize<Person>(secondJson, serializeOptions);
Console.WriteLine(secondPerson);
Console.WriteLine(secondPerson.OtherInfo is JobInfo);
Console.WriteLine(secondPerson.OtherInfo is ParentsInfo);

public record Person(string Name, string InfoDescription, object OtherInfo);

public record JobInfo(string Company, string Role);

public record ParentsInfo(string MotherName, string FatherName);

public class BaseInfoConverter : JsonConverter<Person>
{
    public override Person Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        if (!JsonDocument.TryParseValue(ref reader, out var doc))
            goto nothing;

        var rootElement = doc.RootElement;
        if (rootElement.TryGetProperty(nameof(Person.Name), out var nameProp) &&
            rootElement.TryGetProperty(nameof(Person.InfoDescription), out var infoDescProp) &&
            rootElement.TryGetProperty(nameof(Person.OtherInfo), out var otherInfoProp))
        {
            var name = nameProp.GetString()!;
            var infoDesc = infoDescProp.GetString()!;

            object baseInfo = infoDesc switch
            {
                nameof(JobInfo) => JsonSerializer.Deserialize<JobInfo>(otherInfoProp.GetRawText(), options)!,
                nameof(ParentsInfo) => JsonSerializer.Deserialize<ParentsInfo>(otherInfoProp.GetRawText(), options)!
            };
            return new Person(name, infoDesc, baseInfo!);
        }
    nothing:
        return default;
    }

    public override void Write(Utf8JsonWriter writer, [DisallowNull] Person value, JsonSerializerOptions options)
    {
        var cloneSettings = new JsonSerializerOptions(options);
        cloneSettings.Converters.Remove(this);
        JsonSerializer.Serialize(writer, value, cloneSettings);
    }
}