Question

我有两个问题

有没有办法初始化一个类和所有子类，所以代码中新项的所有元素都为null？

如何处理类型项列表。 EmbeddedGenerator并停止错误

 Object reference not set to an instance of an object.
   at ConsoleApplication1.Program.SetProperty(String compoundProperty,
   Object target, String value)
   at ConsoleApplication1.Program.Main(String[] args)
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly,
   String[] args)
   at System.AppDomain.ExecuteAssembly(String assemblyFile,
   Evidence assemblySecurity, String[] args)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.Run
   (ExecutionContext executionContext, ContextCallback callback,
    Object state, Boolean ignoreSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext
   executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

（new System.Collections.Generic.Mscorlib_CollectionDebugView（（（System.Collections.Generic.List）（target））））。Items [0] .id.id_high

示例“class1.properity1 = 1”

我遇到了一个错误，这里是一个简短的控制台应用程序，概述了错误我试图将id_high的值设置为1路径为generator.contents [0] .id.id_high

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using Items;
    using System.Reflection;

    namespace ConsoleApplication1
    {
     class Program
     {
      static List<SavedItem> items = new List<SavedItem>();
      static void Main(string[] args)
      {
       Items.SavedItem item = new Items.SavedItem();
       item.generator = new Items.Generator();
       item.generator.contents = new List<Items.EmbeddedGenerator>();
       item.generator.contents.Add(new Items.EmbeddedGenerator());
       item.generator.contents[0].id = new OnlineService.ItemId();

       SetProperty(".generator.contents[0].id.id_high", item, "1");

       items.Add(item);
      }

      //jon skeet's modified method
      public static void SetProperty(string compoundProperty, 
      object target, string value)
      {
       string[] bits = compoundProperty.Split('.');
       for (int i = 0; i < bits.Length - 1; i++)
       {
        if (bits[i].IndexOf('[') > 0)
        {
         bits[i] = bits[i].Substring(0, bits[i].IndexOf('['));
        }

        PropertyInfo propertyToGet = target.GetType().GetProperty(bits[i]);
        target = propertyToGet.GetValue(target, null); 
       }
       if (bits[bits.Length - 1].IndexOf('[') > 0)
       {
        bits[bits.Length - 1] = bits[bits.Length - 1].Substring
        (0, bits[bits.Length - 1].IndexOf('['));
        value = value.Trim('{', '}');

        PropertyInfo lstpropertyToSet = target.GetType().GetProperty(bits.Last());
        if (value != "null")
        {

         List<int> list = new List<int>();
         foreach (string s in value.Split(','))
         {
          list.Add(Int32.Parse(s));
         }
         lstpropertyToSet.SetValue(target, 
          Convert.ChangeType(list, lstpropertyToSet.PropertyType)
          , null);
        }

        return;
       }
       PropertyInfo propertyToSet = target.GetType().GetProperty(bits.Last());
       if (value != "null")
       {
        propertyToSet.SetValue(target,
         Convert.ChangeType(value, propertyToSet.PropertyType),
         null);
       }
       return;
      }

     }
    }


   //....Items has an id_high separate from program   
    namespace Items
    {
     public partial class SavedItem
     {
      public SavedItem() { }
      private Items.Generator _generator = null;
      [global::System.ComponentModel.DefaultValue(null)]
      public Items.Generator generator
      {
       get { return _generator; }
       set { _generator = value; }
      }
      //....
     }
     public partial class Generator 
     {
      public Generator() { }
      private System.Collections.Generic.List<EmbeddedGenerator> _contents = 
       new System.Collections.Generic.List<EmbeddedGenerator>();
      public System.Collections.Generic.List<EmbeddedGenerator> contents
      {
       get { return _contents; }
       set { _contents = value; }
      }
      //.....
     }
     public partial class EmbeddedGenerator
     {
      public EmbeddedGenerator() { }

      private OnlineService.ItemId _id;
      public OnlineService.ItemId id
      {
       get { return _id; }
       set { _id = value; }
      }
      //....
     }
    }
    //....onlineService has an id_high separate from ConsoleApplication1 and Items
    namespace OnlineService
    {
     public partial class ItemId 
     {
      public ItemId() { }

      private ulong _id_high;
      public ulong id_high
      {
       get { return _id_high; }
       set { _id_high = value; }
      }
     }
     //....
    }

此代码将正常运行，直到它到达内容集合，回答第一个问题可能解决我的问题，但我认为不会，因为并非所有属性都需要一个值，如果有的话会导致问题。

编辑：添加此项有助于将属性添加到目标但现在“不能将带有[]的索引应用于'object'类型的表达式当您尝试制作目标时，请参阅第1项

item.generator.contents.Add（new Items.EmbeddedGenerator（））; item.generator.contents [0] .id = new OnlineService.ItemId（）;

Answer 1

尝试：

公开属性。

错误是因为“bits [i]”中的属性名称不存在目标。您提供了错误的属性名称。通过有效财产，它会工作。

PropertyInfo propertyToGet = target.GetType().GetProperty(bits[i]);

// bits[i] property doesnot exists in target.

target = propertyToGet.GetValue(target, null); //here is the issues

带字符串的字符串的嵌套属性错误

1 个答案: