Question

我有一个课程如下：

using System;
using System.Collections;
using System.Collections.Generic;

namespace DataBinding.Schemas.Scenario.ViewModels
{
    public class InternationalRowViewDetailsModel: IEnumerable
    {
        public InternationalRowViewDetailsModel()
        {
            Country = new System.Collections.Generic.Dictionary<object, object>();
            RateEUR = new System.Collections.Generic.Dictionary<object, object>();
            RateGBP = new System.Collections.Generic.Dictionary<object, object>();
            RateUSD = new System.Collections.Generic.Dictionary<object, object>();
        }

        public Dictionary<object, object> Country { get; set; }
        public Dictionary<object, object> RateEUR { get; set; }
        public Dictionary<object, object> RateGBP { get; set; }
        public Dictionary<object, object> RateUSD { get; set; }

        public IEnumerator GetEnumerator() { return (IEnumerator)this; }
    }
}

现在我试图按如下方式遍历InternationalRowViewDetailsModel的值：

foreach (InternationalRowViewDetailsModel currentRow in viewModel)
{
   Row newRow = FillInternationalNumberRow(itemRow, currentRow);
   tableNode.Rows.Add(newRow);
}

我想使用foreach并将每个当前行发送到填充表格列的方法FillInternationalNumberRow。

 private static Row FillInternationalNumberRow(Row rowTemplate, InternationalRowViewDetailsModel internationalViewModel)
        {
            Row newRow = rowTemplate.Clone(true) as Row;
            int currentCell = 0;
            if (newRow != null)
            {
                newRow.Cells[currentCell++].FirstParagraph.Runs[0].Text = internationalViewModel.Country.ToString();
                newRow.Cells[currentCell++].FirstParagraph.Runs[0].Text = internationalViewModel.RateEUR.ToString();
                newRow.Cells[currentCell++].FirstParagraph.Runs[0].Text = internationalViewModel.RateGBP.ToString();
                newRow.Cells[currentCell++].FirstParagraph.Runs[0].Text = internationalViewModel.RateUSD.ToString();
            }
            return newRow;
        }

但是我收到以下错误：无法转换类型为＆＃39; DataBinding.Schemas.Scenario.ViewModels.InternationalRowViewDetailsModel＆＃39;的对象输入＆＃39; System.Collections.IEnumerator＆＃39;

Answer 1

您的班级实施IEnumerable：

public class InternationalRowViewDetailsModel: IEnumerable

然而，您正试图将其投射为IEnumerator：

public IEnumerator GetEnumerator() { return (IEnumerator)this; }

您要迭代的对象也必须实现IEnumerator，以便代码知道如何遍历您的集合。

Answer 2

您没有正确实现界面。这是一个实现IEnumerable：

的类型

public class A : IEnumerable {
   private List<string> items = new List<string>();

   public IEnumerator GetEnumerator() {
      return this.items.GetEnumerator();
   }
}

在上面的代码中，我只是返回内部列表的IEnumerator。

请谨记使用IEnumerable时，会产生Object类型的项目。所以即使在上面我有一个List<string>，当遍历它时，它将返回类型Object。如果可能，尝试使用通用的IEnumerable<T>来避免装箱和拆箱。

无法转换类型＆＃39; InternationalRowViewDetailsModel＆＃39;输入＆＃39; System.Collections.IEnumerator＆＃39;

2 个答案: