Question

我现在正在使用C＃Linq我将DataTable转换为List 我被困了...... 给我正确的方向谢谢..

    private void treeview1_Expanded(object sender, RoutedEventArgs e)
    {

        coa = new List<string>();
        //coa = (List<string>)Application.Current.Properties["CoAFull"];
        HMDAC.Hmclientdb db = new HMDAC.Hmclientdb(HMBL.Helper.GetDBPath());

        var data = (from a in db.CoA
                    where a.ParentId == 0 && a.Asset == true
                    select new { a.Asset, a.Category, a.CoAName, a.Hide, a.Recurring, a.TaxApplicable });

        DataTable dtTable = new DataTable();
        dtTable.Columns.Add("Asset", typeof(bool));
        dtTable.Columns.Add("Category", typeof(string));
        dtTable.Columns.Add("CoAName", typeof(string));
        dtTable.Columns.Add("Hide", typeof(bool));
        dtTable.Columns.Add("Recurring", typeof(bool));
        dtTable.Columns.Add("TaxApplicable", typeof(bool));

        if (data.Count() > 0)
        {
            foreach (var item in data)
            {
                DataRow dr = dtTable.NewRow();
                dr["Asset"] = item.Asset;
                dr["Category"] = item.Category;
                dr["CoAName"] = item.CoAName;
                dr["Hide"] = item.Hide;
                dr["Recurring"] = item.Recurring;
                dr["TaxApplicable"] = item.TaxApplicable;
                dtTable.Rows.Add(dr);

            }
        }


        coa = dtTable;



    }

Answer 1

您似乎已经拥有了一个强类型列表。为什么要将其转换为弱类型的DataTable然后再回到列表?????

var data = 
    from a in db.CoA
    where a.ParentId == 0 && a.Asset == true
    select new 
    { 
        a.Asset, 
        a.Category, 
        a.CoAName, 
        a.Hide, 
        a.Recurring, 
        a.TaxApplicable 
    };
var list = data.ToList();

如果您希望能够在方法范围之外使用此列表，请定义一个包含不同属性的类型，并在select语句中使用此类型而不是匿名类型，如：

var data = 
    from a in db.CoA
    where a.ParentId == 0 && a.Asset == true
    select new MyType
    { 
        Asset = a.Asset, 
        Category = a.Category, 
        CoAName = a.CoAName, 
        Hide = a.Hide, 
        Recurring = a.Recurring, 
        TaxApplicable = a.TaxApplicable 
    };
List<MyType> list = data.ToList();

Answer 2

根据您显示的代码，您不需要数据表：

var data = (from a in db.CoA 
    where a.ParentId == 0 && a.Asset == true 
    select new { a.Asset.ToString() + a.Category.ToString() 
        + a.CoAName.ToString()... }).ToList();

Answer 3

如果确实想要将数据表转换为1D列表，则可以这样做

foreach (DataRow row in dtTable.Rows) 
{
    foreach (DataColumn col in dtTable.Columns)
    {
        coa.Add(row[col]);
    }
}

Answer 4

正如您在linq查询中使用Select new它会找到对象。你能做的是

var data = (from a in db.CoA
                    where a.ParentId == 0 && a.Asset == true
                    select new { a.Asset, a.Category, a.CoAName, a.Hide, a.Recurring, a.TaxApplicable });

这是您的查询，您可以在查询中选择多个列。因此，您无法将数据转换为单个字符串列表。你可以做的是在一个字符串中连接所有列，然后将它们添加到字符串列表中。

要做到这一点修改您的查询，如'CK'说

var data = (from a in db.CoA 
    where a.ParentId == 0 && a.Asset == true 
    select new { a.Asset.ToString() + a.Category.ToString() 
        + a.CoAName.ToString()... }).ToList();

然后再做

List<string> name  = new List<string>(data.ToList());

如何在C＃</string>中将DataTable转换为List <string>

4 个答案: