C#：“'System.Collections.Generic.Dictionary<object,object>.KeyCollection' 不包含 'ToList' 的定义”错误

Question

我有以下代码试图在字典中获取值，但似乎无法正常工作。

using System;
using System.Collections.Generic;
using System.Linq;
using Newtonsoft.Json.Linq;

namespace DemoTests
{
    class Program
    {
        static void Main(string[] args)
        {
            string jsonString = "{\"Name\":\"Bob Smith\",\"mainTitle\":\"Title1\",\"emailList\":[\"test.e@example.com\"],\"rowCount\":\"4\",\"emailSubject\":\"Test Email\",\"items\":{\"sheets\":[[{\"ID\": \"4564342\", \"start\": \"08:00\"}]]}}";
            JObject jsonObj = JObject.Parse(jsonString);
            Dictionary<dynamic, dynamic> results = jsonObj.ToObject<Dictionary<dynamic, dynamic>>();
  
            List<dynamic> subList = results["items"]["sheets"].ToObject<List<dynamic>>();
            foreach (dynamic tableEntries in subList) 
            {
                var entryDict = tableEntries[0].ToObject<Dictionary<dynamic, dynamic>>();
                for (int k = 0; k < entryDict.Keys.Count; k++)
                {
                    String key = entryDict.Keys.ToList()[k];
                    Console.WriteLine(key);
                }
            }
      
            }

    }
}

我在行 String key = entryDict.Keys.ToList()[k];

上遇到错误

Exception thrown: 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' in System.Linq.Expressions.dll An unhandled exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in System.Linq.Expressions.dll 'System.Collections.Generic.Dictionary<object,object>.KeyCollection' does not contain a definition for 'ToList'

我怎样才能得到它运行？我是 C# 的新手，所以也愿意接受更好的方法来编写我的代码

Answer 1

错误信息告诉你entryDict.Keys没有函数ToList() .Keys 是一个密钥集合，它使用枚举器遍历它。您不能像 array/list.

那样访问它

你要的是这个：

foreach (var key in results.Keys)
{
    Console.WriteLine(key.ToString());
}

Answer 2

使用构造函数创建列表

List<string> keyList = new List<string>(entryDict.Keys);
for (int k = 0; k < entryDict.Keys.Count; k++){
    String key = keysList[k];
    Console.WriteLine(key);
}

C#：“'System.Collections.Generic.Dictionary<object,object>.KeyCollection' 不包含 'ToList' 的定义”错误

C#: "'System.Collections.Generic.Dictionary<object,object>.KeyCollection' does not contain a definition for 'ToList'" error

c#

generics

dictionary

tostring