IEnumerable ;使用匿名方法

发布于 2024-11-02 17:39:40 字数 713 浏览 1 评论 0 原文

我不知道如何摆脱这个错误？

错误 1 使用通用类型“System.Collections.Generic.IEnumerable”需要 1 个类型参数 C:\Users\huzaifa.gain\documents\visual studio 2010\Projects\VendInvoiceImport\VendInvoiceImport\Program.cs 34 24 VendInvoiceImport

private static IEnumerable<string , string >  DistinctInvoiceNumber(DataTable   VendorInvoiceStagingTable)
       {
           var InvoiceLinecollection = VendorInvoiceStagingTable.AsEnumerable().Select(t => new {  number = t.Field<string>(VendInvoice.Number),LineNumber = t.Field<string>(VendInvoice.LineNumber)}).Distinct();
        return InvoiceLinecollection;
      }

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原文

I dont know how to get rid of this error ?

Error 1 Using the generic type 'System.Collections.Generic.IEnumerable' requires 1 type arguments C:\Users\huzaifa.gain\documents\visual studio 2010\Projects\VendInvoiceImport\VendInvoiceImport\Program.cs 34 24 VendInvoiceImport

private static IEnumerable<string , string >  DistinctInvoiceNumber(DataTable   VendorInvoiceStagingTable)
       {
           var InvoiceLinecollection = VendorInvoiceStagingTable.AsEnumerable().Select(t => new {  number = t.Field<string>(VendInvoice.Number),LineNumber = t.Field<string>(VendInvoice.LineNumber)}).Distinct();
        return InvoiceLinecollection;
      }

enter image description here

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横笛休吹塞上声 2024-11-09 17:39:40

您的 Linq 查询返回匿名类型的序列，但方法不能返回匿名类型。您有多种选择：

返回一个 IEnumerable>

private static IEnumerable>>不同发票编号（数据表供应商发票暂存表）
{
    var InvoiceLinecollection = VendorInvoiceStagingTable
                                    .AsEnumerable()
                                    .Select(t => Tuple.Create(t.Field(VendInvoice.Number), t.Field(VendInvoice.LineNumber)))
                                     。清楚的（）;
    返回 InvoiceLine 集合；
}

, string>>

按照另一个答案中的建议返回一个 IDictionary （假设您的查询不返回重复的键）

private static IDictionary;不同发票编号（数据表供应商发票暂存表）
{
    var InvoiceLinecollection = VendorInvoiceStagingTable
                                    .AsEnumerable()
                                    .Select(t => Tuple.Create(t.Field(VendInvoice.Number), t.Field(VendInvoice.LineNumber)))
                                    。清楚的（）
                                    .ToDictionary(t => t.Item1, t => t.Item2);
    返回 InvoiceLine 集合；
}

为此目的创建一个类 2字符串属性并返回该类的序列

private static IEnumerable;不同发票编号（数据表供应商发票暂存表）
{
    var InvoiceLinecollection = VendorInvoiceStagingTable
                                    .AsEnumerable()
                                    .Select(t => new InvoiceLine(t.Field(VendInvoice.Number), t.Field(VendInvoice.LineNumber)))
                                    。清楚的（）;
    返回 InvoiceLine 集合；
}

Your Linq query returns an sequence of anonymous type, but methods can't return anonymous types. You have several options:

return an IEnumerable<Tuple<string, string>>

private static IEnumerable<Tuple<string, string>>  DistinctInvoiceNumber(DataTable   VendorInvoiceStagingTable)
{
    var InvoiceLinecollection = VendorInvoiceStagingTable
                                    .AsEnumerable()
                                    .Select(t => Tuple.Create(t.Field<string>(VendInvoice.Number), t.Field<string>(VendInvoice.LineNumber)))
                                     .Distinct();
    return InvoiceLinecollection;
}

return a IDictionary<string, string> as suggested in another answer (assuming your query doesn't return duplicate keys)

private static IDictionary<string, string> DistinctInvoiceNumber(DataTable   VendorInvoiceStagingTable)
{
    var InvoiceLinecollection = VendorInvoiceStagingTable
                                    .AsEnumerable()
                                    .Select(t => Tuple.Create(t.Field<string>(VendInvoice.Number), t.Field<string>(VendInvoice.LineNumber)))
                                    .Distinct()
                                    .ToDictionary(t => t.Item1, t => t.Item2);
    return InvoiceLinecollection;
}

create a class for this purpose with 2 string properties and return a sequence of that class

private static IEnumerable<InvoiceLine>  DistinctInvoiceNumber(DataTable   VendorInvoiceStagingTable)
{
    var InvoiceLinecollection = VendorInvoiceStagingTable
                                    .AsEnumerable()
                                    .Select(t => new InvoiceLine(t.Field<string>(VendInvoice.Number), t.Field<string>(VendInvoice.LineNumber)))
                                    .Distinct();
    return InvoiceLinecollection;
}

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清风疏影 2024-11-09 17:39:40

为什么不使用 Dictionary 来代替？

private static Dictionary<string , string >  DistinctInvoiceNumber(DataTable   VendorInvoiceStagingTable)
       {
           var InvoiceLinecollection = VendorInvoiceStagingTable.AsEnumerable().Select(t => new {  number = t.Field<string>(VendInvoice.Number),LineNumber = 
                 t.Field<string>(VendInvoice.LineNumber)}).ToDictionary();
            return InvoiceLinecollection;
          }

Why you do not use Dictionary<string, string> instead?

private static Dictionary<string , string >  DistinctInvoiceNumber(DataTable   VendorInvoiceStagingTable)
       {
           var InvoiceLinecollection = VendorInvoiceStagingTable.AsEnumerable().Select(t => new {  number = t.Field<string>(VendInvoice.Number),LineNumber = 
                 t.Field<string>(VendInvoice.LineNumber)}).ToDictionary();
            return InvoiceLinecollection;
          }

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