集合已修改 IGrouping of Invoices

Question

我有一个List<IGrouping<string, InvoiceCount>> 来检查发票中的位置。它工作得很好，但是当一个职位已经在另一个发票中时，应该删除该职位，但它会出现异常

“集合已修改；枚举操作可能无法执行。”

我不知道如何解决这个问题

 private static void ValidateInvoices(List<IGrouping<string, InvoiceCount>> invo)
        {
            var validationErrors = new StringBuilder();
            foreach (IGrouping<string, InvoiceCount> invoice in invo)
            {
                for (var line = 1; line < invoice.Count(); line++)
                {
                    if (!invoice.ElementAt(line).IsInSameInvoice(invoice.First()))
                    {
                        validationErrors.Append("Validation error in Invoice" + invoice.Key + " in line " + (line + 1) + Environment.NewLine);
                        if (invo.Contains(invoice))
                            try
                            {
                                invo.Remove(invoice);
                            }
                            catch (Exception ex)
                            {
                                throw ex;
                            }
                    }
                }
            }
            if (validationErrors.Length > 0)
                throw new Exception(validationErrors.ToString());
        }

Answer 1

删除元素后需要刷新集合。 尝试更改您的代码，如下所示，看看它是否有效：

代码：

var newList = invo;
foreach (IGrouping<string, InvoiceCount> invoice in invo)
{
       for (var line = 1; line < invoice.Count(); line++)                
       {
           if (YOUR CONDITION HERE)
           {
              newList.Remove(invoice );
              invo= newList;
           }
       }
}

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注意： How to modify a collection during iteration