C＃错误“的类型初始值设置...抛出异常 [英] C# Error "The type initializer for ... threw an exception

问题描述

此错误仅在某些计算机上发生。通过读取堆栈信息，当我在静态类中调用此静态方法（FormatQuery）时会出现一些问题：

This error occurs only in some computers. By reading the stack information, there is some problem when I call to this static method ("FormatQuery") in a static class:

using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Windows.Forms;
using DevExpress.XtraEditors;
using FlexCel.Report;
using FlexCel.XlsAdapter;
using ComboBox=System.Windows.Forms.ComboBox;

namespace XSoftArt.A
{
    static class RHelper
    {
        private static string FormatQuery(string FieldName, int Count,
            CheckedListBox chekedListBox)
        {
            string ID = string.Empty;
            int n = Count;

            foreach (DataRowView item in chekedListBox.CheckedItems)
            {
                ID = ID + item["" + FieldName + ""];
                if (n > 1)
                {
                    ID = ID + " , ";
                    n--;
                }
            }
            return ID;
        }

        public static string FormatQuery(CheckedListBox chekedListBox)
        {
            return FormatQuery(chekedListBox.ValueMember,
                chekedListBox.CheckedItems.Count, chekedListBox);
        }
    }

那么，问题是什么？我该如何解决呢？

So, what's the problem? How do I solve it? Is there something wrong with the project configuration or debbuging mode or what?

错误信息：

   at XSoftArt.EVS.ReportHelper.FormatQuery(CheckedListBox chekedListBox)
   at XSoftArt.EVS.NewEmailSelectClient.LoadList_v2(String search, TextBox txtbox)
   at XSoftArt.EVS.NewEmailSelectClient.LoadContacts()
   at XSoftArt.EVS.NewEmailSelectClient.button7_Click(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

推荐答案

我尝试过您的代码：

   CheckedListBox cb = new CheckedListBox();
   for (var i = 1; i < 11; i++)
      cb.Items.Add("Item " + i, i % 3 == 0);

   string fmt = RHelper.FormatQuery(cb);
   Console.WriteLine(fmt);
   Console.ReadLine();

在此行中抛出异常：

   foreach (DataRowView item in chekedListBox.CheckedItems)

  Unable to cast object of type 'System.String' to type
    'System.Data.DataRowView'.

也许你也面临同样的问题。而不是转换到 DataRowView ，尝试进行以下更改：

Maybe you are also facing the same kind of problem. Instead of casting to DataRowView, try making the following changes:

     foreach (var item in chekedListBox.CheckedItems)
     {
         ID = ID + item.ToString(); // item["" + FieldName + ""];

因为CheckedListBox中的项目是 object 类型。

Because items in CheckedListBox are of object type.

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