如何在Unity3D中使用LitJson在c#中编辑JSON值? [英] How do I edit JSON values in c# with LitJson in Unity3D?

问题描述

因此，我尝试获取.json文件并用c#读取它，然后修改其中一个值，然后刷新.json文件，以便更改值.我知道如何读取文件以及如何覆盖文件，但是如何更改文件中一项特定项的一项特定值?

So I am trying to take a .json file and read it in c#, then modify one of the values, and then refresh the .json file so that the value is changed. I know how to read the file, and how to overwrite the file, but how do I change one specific value of one specific item in the file?

此脚本的目标是创建一个库存系统，可以在其中通过json文件记录余额.我想使用BalanceChange()函数转到文件，使用ID变量找到正确的项目，然后相应地更改余额.

The goal of this script is to create an inventory system, where the balance can be recorded through the json file. I want to use the BalanceChange() function to go to the file, find the correct item using the ID variable, and then change the balance accordingly.

这是我的.json脚本:

Here is my .json script:

[
    {
    "name":"Potion",
    "id":1,
    "balance":5
    },
    {
    "name":"Neutral Bomb",
    "id":2,
    "balance": 4
    }
]

这是我的c#脚本:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.IO;
using LitJson;


public class Item
{
    public string Name  { get; set; }
    public int Id       { get; set; }
    public int Balance  { get; set; }

    public Item(string name1, int id1, int balance1) {
        Name = name1;
        Id = id1;
        Balance = balance1;
    }
}

public class InventoryAttempt : MonoBehaviour
{
    public static void BalanceChange(string filePath, int ID, int change)
    {
        string jsonString = File.ReadAllText(Application.dataPath + filePath);
        List<Item> itemList = JsonMapper.ToObject<List<Item>>(jsonString);
        itemList [ID].Balance += change;
        jsonString = JsonMapper.ToJson (itemList).ToString();
        File.WriteAllText (Application.dataPath + filePath, jsonString);
    }

    void Start()
    {
        BalanceChange ("/Scripts/inventory.json", 1, -1);
    }
}

由于某些原因，该脚本无法正常工作.我不断收到此错误:

This script isn't working for some reason. I keep getting this error:

MissingMethodException: Method not found: 'Default constructor not found...ctor() of Item'.
System.Activator.CreateInstance (System.Type type, Boolean nonPublic) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Activator.cs:368)
System.Activator.CreateInstance (System.Type type) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Activator.cs:254)
LitJson.JsonMapper.ReadValue (System.Type inst_type, LitJson.JsonReader reader)
LitJson.JsonMapper.ReadValue (System.Type inst_type, LitJson.JsonReader reader)
LitJson.JsonMapper.ToObject[List`1] (System.String json)
InventoryAttempt.BalanceChange (System.String filePath, Int32 ID, Int32 change) (at Assets/Scripts/InventoryAttempt.cs:26)
InventoryAttempt.Start () (at Assets/Scripts/InventoryAttempt.cs:34)

推荐答案

是的，这就是这些库的目的.我对LitJson并不特别熟悉，但是其中大多数是相似的:

Yes, that's the purpose of these librarys. I'm not familiar with LitJson specifically but most of these are similar:

基于疑问示例；我们将json转换为对象，更改属性，然后再次将其保存到json:

Based on the doucmentation examples; we take json and turn it to an object, change a property and then save it to json again:

public class Person
{
    // C# 3.0 auto-implemented properties
    public string   Name     { get; set; }
    public int      Age      { get; set; }
    public DateTime Birthday { get; set; }
}


public class Example{
    public static void JsonToPerson()
    {
    string json = @"
        {
            ""Name""     : ""Thomas More"",
            ""Age""      : 57,
            ""Birthday"" : ""02/07/1478 00:00:00""
        }";

    Person thomas = JsonMapper.ToObject<Person>(json);

    thomas.Age = 23;

    string newJson = JsonMapper.ToJson(thomas);
    }
}

要编辑属性，我们只需更改Objects属性.在我的示例中，我将thomas.Age编辑为23，然后再次将该对象序列化为json. 应该给我们下面的json:

To edit a property we simply change the Objects property. In my example I edit thomas.Age to 23 and then serialize the object to json again. Should give us the following json:

{
    ""Name""     : ""Thomas More"",
    ""Age""      : 23,
    ""Birthday"" : ""02/07/1478 00:00:00""
}

如果您想在一个json中包含多个Person，请将它们添加到列表中并序列化该列表.如果您想要每个不同对象的唯一标识符，则可以在Person中添加一个Id属性.像这样:

If you'd like to have many Person in one json, you add them to a list and serialize the list. If you'd like an unique identifier for every distinct object you could, among other things, add an Id property to Person. Like this:

首先将ID属性添加到Person类:

First add the Id propery to the Person class:

public string Id { get; set; }

以及用法/列表序列化:

and the usage/list serialization:

List<Person> people = List<Person>();

Person thomas = new Person();
thomas.Name = "Thomas";
thomas.Id = "0001";
people.Add(thomas);

Person albert = new Person();
albert.Name = "Albert";
albert.Id = "0002";
people.Add(albert);

JsonMapper.ToJson(people);

这应该给你Json这样的东西:

This should give you Json like this:

{
    {
        ""Name""     : ""Thomas"",
        ""Id""       : ""0001""
    },
    {
        ""Name""     : ""Albert"",
        ""Id""       : ""0002""
    }
}

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