c# - 关于 Linq 查询中的 ArrayIndex

Question

当我尝试执行以下操作时，我有 LINQ 表达式节点类型 ArrayIndex is not suported in LINQ to Entities 错误

public List<AttachmentList> ShowAttachments(int type, int ReferenceId)
{

    try
    {
        var attachmentNames =
            (from attachment in tent.Attachments
                where (attachment.Attachment_Type == type
                    && attachment.Attachment_Reference_Pk == ReferenceId)
                select new AttachmentList
                        {
                            Attachment_Pk = attachment.Attachment_Pk,
                            Attachment_File_Path = attachment
                                .Attachment_File_Path.Split(new[] {'$'})[1]
                        }).ToList();

        return attachmentNames;
    }
    catch (Exception ex)
    {
        ExceptionHandler.ExceptionLog(ex);
        return null;
    }
} 

如您所见，我正在尝试拆分包含 '$' 的 Attachmentfilepath 并将第二个值 ([1]) 分配给 Attachment_FilePath

任何人都可以建议我如何拆分并将值分配给同一查询中的 AttachmentList 字符串谢谢

Answer 1

老实说，最简单的方法是在客户端进行拆分，除非您真的需要它成为一个成熟的实体。例如:

var query = from attachment in tent.Attachments
            where attachment.Attachment_Type == type &&
                  attachment.Attachment_Reference_Pk == ReferenceId
            select new { Attachment_Pk, Attachment_File_Path };

// Force the rest to execute client-side.
var attachmentNames = query.AsEnumerable()
                           .Select(x => new AttachmentList {
                               Attachment_Pk = x.Attachment_Pk,
                               Attachment_File_Path = x.Attachment_File_Path
                                                       .Split('$')[1]
                           })
                           .ToList();