using Newtonsoft.Json;

using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        // Collection of FormData

        FormData[] formData = new FormData[]{null, null, null};

        // Filter nulls from formdata

        formData = formData.Where(_form => _form != null).ToArray();

​

        Form form = new Form(1, "TestVisibility", formData);

        // Serialise to JSON

        var serialisedForm = JsonConvert.SerializeObject(form);

        // Output serialised JSON

        Console.WriteLine(serialisedForm);

    }

}

​

public class Form

{

  public int FormId { get; set; }

  public string Visibility { get; set; }

  public IEnumerable<FormData> FormData { get; set; }

  public Form() { }

  public Form(int formId, string visibility, IEnumerable<FormData> formData)

  {

     FormId = formId;

     Visibility = visibility;

     FormData = formData;

  }

}

​

public class FormData

{

  public FormData(int formDataId, string field, string schema)

  {

    FormDataId = formDataId;

    Field = field;

    Schema = schema;

  }

  public int FormDataId { get; set; }

  public string Field { get; set; }

  public string Schema { get; set; }

}