I have some trouble with nested class in Unity

Question

I think i have some problem try to explain what i mean so i gonna explain what i do and what my code turn to from begining.

I have this code that save my data to json, it work fine, it print json perfectly

Script: GiftValue

[SerializeField]
 public class Gift
 {
    public int GValue 
    public string GName 
    public int GAmount
    public float GWeight
 }

Script: EditAddGift

 [SerializeField]
 public List<Gifts> _Gift = new List<Gifts>();

///those code above is what i missing before.
 Gifts NewGift = new Gifts
    {
        GValue = DropDownValueGift,
        GName = ifGiftDetailName.text,,
        GAmount = iAmount,
        GWeight = fWeight,


    };
_Gift.Add(NewGift);
SaveToJson(_Gift, DATABASE_NAME);

This is my code before I realise that my class need to split to GiftDetail and Gift. After that I realise that I need to split "Gifts" to 2 part, "Gifts" and "GiftDetail". Soo i google and found about nested class, after some time my Script GiftValue become this

[System.Serializable]
public class GiftDetail
{
    public int GDetailValue 
    public string GDetailName 
    public double GDetailWeight 
    public int GDetailAmount 
}

[System.Serializable]
public class Gift
{
    public int GValue 
    public string GName 
    public List<GiftDetail> GiftDetail 
}

I have trouble write code after change because i ONLY KNOW HOW TO call normal class like this :

Gifts NewGift= New Gifts

{ ..... }

This is what i try to do

        GiftDetail NewGiftDetail = new GiftDetail
        {

            GDetailValue = DropDownValueGiftDetail,
            GDetailAmount = iAmount,
            GDetailName = ifGiftDetailName.text,
            GDetailWeight = Fweight,
        };



        Gifts NewGift = new Gifts
        {
            GValue = DropDownValueGift,
            GName = txtDropDownGift,


            //What i want to know is how to change  NewGiftDetail
            //or change class Gift or class GiftDetail or....
            // so i can put GiftDetail in here



           //GiftDetail = NewGiftDetail,// let just delete this,
           // because i don't know how to call this
        };

So that finally i will have my json file look like this

    [
      {
        "GValue": 1,
        "GName": "Gift 3",
        "GiftDetail": 
        [
        {
          "GDetailValue": 3,
          "GDetailName": "2",
          "GDetailWeight": 3.0,
          "GDetailAmount": 4
        },
        {
          "GDetailValue": 3,
          "GDetailName": "2",
          "GDetailWeight": 3.0,
          "GDetailAmount": 4
        }

        ],
      },
]

I try someway before like change Gift to public class Gift<T> blah blah.. but i think i should show my code from before it downfall to help you guy more clear on what i want to achive

---

Code i use to delete before i change to Gift and GiftDetail

            if (_Gift.Exists(x => x.GValue== DropDownValuePhanQua ))
            {  

                int i = 0;        
                while (i <_Gift.Count && _Gift[i].GValue != DropDownValuePhanQua)
                        i++;
                _Gift.RemoveAt(i);

            }
            _Gift.Add(NewGift);
            SaveToJson(_Gift, DATABASE_NAME);

I change it to this

if (_Gift.Exists(x => x.GValue== DropDownValuePhanQua ))
///still don't know how to get GDetailValue , it only let me access to x.GiftDetail
                {  
                    GiftDetail NewGiftDetail3 = new GiftDetail
                    {
                        GDetailValue = DropDownValuePhanQua,
                        GDetailAmount = iSoLuongPhanQua,
                        GDetailName = ifTenPhanQua.text,
                        GDetailWeight = fTileRaPhanQua,
                    };
                    int i = 0;        
                    while (i <_Gift.Count && _Gift[i].GValue != DropDownValuePhanQua)
                            i++;
                    NewGift.GiftDetails.Add(NewGiftDetail3);
                    _Gift.RemoveAt(i);
                }
                _Gift.Add(NewGift);
                SaveToJson(_Gift, DATABASE_NAME);

If i use code about it will return json but it keep replace the second GiftDetail

 [ {
        "GValue": 1,
        "GName": "Phần Quà 1",
        "GiftDetails": [
          {
            "GDetailValue": 5,
            "GDetailName": "3",
            "GDetailWeight": 2.0,
            "GDetailAmount": 4
          },
          {
            "GDetailValue": 6,
            "GDetailName": "Old One",
            "GDetailWeight": 33.0,
            "GDetailAmount": 3
          }
        ]
      }
]

to this

[
{
    "GValue": 1,
    "GName": "Phần Quà 1",
    "GiftDetails": [
      {
        "GDetailValue": 5,
        "GDetailName": "3",
        "GDetailWeight": 2.0,
        "GDetailAmount": 4
      },
      {
        "GDetailValue": 3,
        "GDetailName": "new Gift",
        "GDetailWeight": 33.0,
        "GDetailAmount": 3
      }
    ]
  }
]

Answer 1

There are few ways. Here is one.

Having

[System.Serializable]
public class GiftDetail
{
    public int GDetailValue;
    public string GDetailName;
    public double GDetailWeight;
    public int GDetailAmount;
}

[System.Serializable]
public class Gift
{
    public int GValue;
    public string GName;
    public List<GiftDetail> GiftDetails; // Added 's'
}

you can

GiftDetail NewGiftDetail = new GiftDetail
{
    GDetailValue = DropDownValueGiftDetail,
    GDetailAmount = iAmount,
    GDetailName = ifGiftDetailName.text,
    GDetailWeight = Fweight,
};

GiftDetail NewGiftDetail2 = new GiftDetail
{
    //(...)
};

Gift NewGift = new Gift  //Gift - not gifts
{
    GValue = 1,
    GName = "One",
    GiftDetails = new List<GiftDetail>() { NewGiftDetail, NewGiftDetail2 }
};

GiftDetail d3 = new GiftDetail
{
    //(...)
};

NewGift.GiftDetails.Add(d3);
// NewGift has now 3 details
//Access first detail
NewGift.GiftDetails[0]; // Or .First() with 'using System.Linq`

Answer 2

List<GiftDetail> GiftDetailList =new List<GiftDetail>()
var GD1 = new GiftDetailList ()
{
          GDetailValue= 3,
          GDetailName= "2",
          GDetailWeight= 3.0,
          GDetailAmount= 4
}

similarly create as many Details you want and then

    Gifts NewGift = new Gifts
    {
        GValue = DropDownValueGift,
        GName = txtDropDownGift,    
       GDteails=GiftDetailList 
    };