JsonConvert.Deserializer索引问题 [英] JsonConvert.Deserializer indexing issues

问题描述

在C#中玩Stack集合时，遇到了以下问题.确实，我不确定为什么会这样.请阐明原因和替代解决方案的方法.

While playing around Stack collection in C# I encountered the following issue. Exactly I am not sure why it is happening. Please put some light on the reason and alternative to the solution.

问题-

一个具有Stack作为属性的类.例如，将该类命名为Progress. T是Item类型的类.

A class having Stack as property. For example name that class as Progress. T is of class type Item.

现在，只要用户取得任何进展，我们都将存储在堆栈中.如果用户介于两者之间，那么下一次我们将从该堆栈中窥视该项目.下面的代码段将给出正在尝试的内容的想法...

Now whenever the user makes any progress we will be storing in stack. And if user leaves in between, then next time we will peek the item from the stack so from that stage. Below code snippet will give an idea of what is being tried...

using static System.Console;
using System.Collections.Generic;
using Newtonsoft.Json;

namespace StackCollection
{
    class Program
    {
        static void Main(string[] args)
        {
            Progress progress = new Progress();

            progress.Items.Push(new Item { PlanID = null, PlanName = "Plan A" });

            var jsonString = JsonConvert.SerializeObject(progress);
            var temp = JsonConvert.DeserializeObject<Progress>(jsonString);

            temp.Items.Push(new Item { PlanID = null, PlanName = "Plan B" });

            jsonString = JsonConvert.SerializeObject(temp);
            temp = JsonConvert.DeserializeObject<Progress>(jsonString);

            temp.Items.Push(new Item { PlanID = null, PlanName = "Plan C" });

            jsonString = JsonConvert.SerializeObject(temp);
            temp = JsonConvert.DeserializeObject<Progress>(jsonString);

            WriteLine(temp.Items.Peek().PlanName);

            ReadLine();
        }
    }

    class Progress
    {
        public Stack<Item> Items { get; set; }

        public Progress()
        {
            Items = new Stack<Item>();
        }
    }

    class Item
    {
        public string PlanID { get; set; }

        public string PlanName { get; set; }
    }
}

现在就行-

WriteLine(temp.Items.Peek().PlanName);

应该返回

计划C

但它正在返回

计划B

所以，为什么要更改索引，任何线索或指针都会有所帮助.

So, why the index is being changed, any clue or pointer will be helpful.

推荐答案

似乎堆栈已被序列化为List.问题在于，在解构堆栈时，这不会保留正确的顺序(项目实际上以相反的顺序被推入).这是解决此问题的快速方法:

It seems like the stack is being serialized as a List. The problem is that this does not preserve the proper order when deconstructing the stack (the items are actually pushed in the reverse order). Here's a quick workaround to this issue:

using System;
using static System.Console;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using Newtonsoft.Json;

namespace StackCollection
{
    class Program
    {
        static void Main(string[] args)
        {
            Progress progress = new Progress();

            progress.Items.Push(new Item { PlanID = null, PlanName = "Plan A" });

            var jsonString = JsonConvert.SerializeObject(progress);
            var temp = JsonConvert.DeserializeObject<Progress>(jsonString);

            temp.Items.Push(new Item { PlanID = null, PlanName = "Plan B" });

            jsonString = JsonConvert.SerializeObject(temp);
            temp = JsonConvert.DeserializeObject<Progress>(jsonString);

            temp.Items.Push(new Item { PlanID = null, PlanName = "Plan C" });

            jsonString = JsonConvert.SerializeObject(temp);
            temp = JsonConvert.DeserializeObject<Progress>(jsonString);

            WriteLine(temp.Items.Peek().PlanName);

            ReadLine();
        }
    }

    class Progress
    {
        [JsonIgnore]
        public Stack<Item> Items { get; set; }

        public List<Item> ItemList { get; set; }

        [OnSerializing]
        internal void OnSerializing(StreamingContext context)
        {
            ItemList = Items?.ToList();
        }

        [OnDeserialized]
        internal void OnDeserialized(StreamingContext context)
        {
            ItemList?.Reverse();
            Items = new Stack<Item>(ItemList ?? Enumerable.Empty<Item>());
        }

        public Progress()
        {
            Items = new Stack<Item>();
        }
    }

    class Item
    {
        public string PlanID { get; set; }

        public string PlanName { get; set; }
    }
}

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