Store values to the android device

Question

I am creating inventory system for my game and problem is that i need to create system to store multiple values to my device.

I know there are PlayerPrefs but with that i can only store 2 values (let's say key for one and value for second), but i need something like table. So i have to store something like this in single line:

inventorySlot
itemID
amount

this is simple 3 size value, but also i would need to store 4, 5, or more.

So how can i achieve this?

Here is current code where problem is that storing to json is not working. Look at comment at the end of Debug.Log to see what it displays.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class InventoryModel
{
    public List<InventoryItem> InventoryItems;

    public InventoryModel()
    {
        InventoryItems = new List<InventoryItem>();
    }
}

public class InventoryItem
{
    public int inventorySlot;
    public int itemID;
    public float amount;
}


public class Inventory : MonoBehaviour
{
    private int inventorySlots = 5;

    public Text itemSlot1;

    void Start ()
    {
        AddItemToInventory(1, 0, 2000);
        LoadInventory();
    }

    void Update ()
    {

    }

    public static void AddItemToInventory(int slot, int itemID, float amount)
    {
        InventoryModel im = new InventoryModel();
        InventoryItem ii = new InventoryItem();
        ii.inventorySlot = slot;
        ii.itemID = itemID;
        ii.amount = amount;

        im.InventoryItems.Add(ii);

        foreach(InventoryItem ia in im.InventoryItems)
        {
            Debug.Log(ia.itemID + "-" + ia.amount + "-" + ia.inventorySlot);    //Display 0-2000-1
        }
        string jsonString = JsonUtility.ToJson(im);
        Debug.Log(jsonString);                                                  //Display {}
        PlayerPrefs.SetString("PlayerInventory", jsonString);
    }

    private void LoadInventory()
    {
        foreach(InventoryItem ii in LoadInventoryFromPref().InventoryItems)
        {
            //Doesnt enter this loop
            Debug.Log(ii.inventorySlot);
            Debug.Log(ii.itemID);
            Debug.Log(ii.amount);
            Debug.Log("====");
        }
    }

    private static InventoryModel LoadInventoryFromPref()
    {
        string test = PlayerPrefs.GetString("PlayerInventory");
        Debug.Log(test);                                                        //display {}
        return JsonUtility.FromJson<InventoryModel>(test);
    }

    private static int GetMaxInventorySlots()
    {
        if(PlayerPrefs.HasKey("MIS"))
        {
            return PlayerPrefs.GetInt("MIS");
        }
        else
        {
            return 0;
        }
    }
}

Answer 1

A similar answer was provided here What is the best way to save game state? that uses DataSaver.saveData.

Use PlayerPrefs to store a JSON instead of individual keys. As long as the data is less than 1MB in size, PlayerPrefs is the best option.

Since all you wish to store is an array of:

inventorySlot
itemID
amount

You can do the following:

{
  "Items": [
    {
      "inventorySlot": 1,
      "itemID": "123ABC",
      "amount": 234
    },
    {
      "inventorySlot": 2,
      "itemID": "123ABC",
      "amount": "554"
    }
  ]
}

Then store that in PlayerPref by assigning it to a key of your choice using setString

You can then utilize Unity's JsonUtility to serialize/deserialize the JSON.

The Model (Note: Decorate models with [System.Serializable]:

[System.Serializable]
public class InventoryModel
{
    public List<Item> Items = new List<Item>();
}

[System.Serializable]
public class Item
{
    public int inventorySlot;
    public string itemID;
    public int amount;
}

Here's a full example:

    InventoryModel invModel = new InventoryModel();

    Item model = new Item();
    model.inventorySlot = 1;
    model.itemID = "123ABC";
    model.amount = 234;

    Item model2 = new Item();
    model2.inventorySlot = 2;
    model2.itemID = "123ABC";
    model2.amount = 554;

    invModel.Items.Add(model);
    invModel.Items.Add(model2);

    //Generate JSON then save it
    string yourModelJson = JsonUtility.ToJson(invModel);
    PlayerPrefs.SetString("InventoryKey", yourModelJson);

   //Read JSON back to Model
   InventoryModel testModel = new InventoryModel();
   string rawJsonFromPref = PlayerPrefs.GetString("InventoryKey");
   testModel = JsonUtility.FromJson<InventoryModel>(rawJsonFromPref);

Answer 2

Try to use sqlite then you do not need to worry about how much data you store.