c# - 将我的 linq 查询结果集添加到数据集，c# asp.net 3.5

Question

我的查询是:

var query1 = from u in dc.Usage_Computers.AsEnumerable
             where u.DomainUser == s3
             orderby u.OperationTime descending
             select new
             {
                 u.ProgramVersion,
                 u.OperationTime,
                 u.IPaddress,
                 u.ComputerName,
                 u.DomainUser,
                 u.OnNetwork,
                 Operation = u.Operation == 1 ? "Login" :
                             u.Operation == 2 ? "Logoff" :
                             u.Operation == 3 ? "AGNS Connect" :
                             u.Operation == 4 ? "AGNS Disconnect" :
                             "None"
             };

GridView1.DataSource = query1;
GridView1.DataBind();

在使用 gridview 进行数据绑定(bind)后，我想将结果集“query1”添加到数据集或数据表中。谁能告诉我该怎么做？

我在这里看到另一篇帖子也有同样的问题，但那个答案在我身上不起作用......

**注意:我使用的是 VS 2008 **

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Data;

public static class IEnumerableExt
{
    public static DataTable ToDataTable<T>(this IEnumerable<T> things) where T : class
    {
        DataTable tbl = new System.Data.DataTable();
        bool buildColumns = false;
        foreach (var item in things)
        {
            Type t = item.GetType();
            var properties = t.GetProperties();
            if (!buildColumns)
            {
                foreach (var prop in properties)
                {
                    Type ptype = prop.PropertyType;
                    if (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
                    {
                        ptype = Nullable.GetUnderlyingType(prop.PropertyType.UnderlyingSystemType);
                    }
                    DataColumn col = new DataColumn(prop.Name, ptype);
                    tbl.Columns.Add(col);
                }
                buildColumns = true;
            }
            DataRow row = tbl.NewRow();

            foreach (var prop in properties)
            {
                if (prop.GetValue(item, null) == null)
                {
                    row[prop.Name] = DBNull.Value;
                }
                else
                {
                    row[prop.Name] = prop.GetValue(item, null);
                }
            }

            tbl.Rows.Add(row);
        }

        return tbl;
    }
}

没有 CopyToDataTable 除非你处理 DataRows 看看这些:

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=2162392&SiteID=1

http://oakleafblog.blogspot.com/2007/03/linq-missing-todatatable-method-saga.html

比我的代码涉及更多的好选择: http://blogs.msdn.com/aconrad/archive/2007/09/07/science-project.aspx

编辑:更新后可以正常工作