Question

我不知道为什么会这样？

var tradeList = client.getTradeReports(criteria);
tradeGridView.DataSource = tradeList;
int rowCount = tradeGridView.Rows.Count;

foreach (DataGridViewRow row in tradeGridView.Rows)
{
    for (int counter = 0; counter < columnNameAndFlag.Length; counter++)
    {
        if (row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value == null || row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value == DBNull.Value || String.IsNullOrWhiteSpace(row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value.ToString()))
            tradeData.Add("");
        else
        {
            if (columnNameAndFlag[counter].Split('-')[0] == "TransactTime")
                tradeData.Add(dt.AddSeconds(Convert.ToDouble(row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value)).ToLocalTime().ToString());
            else
                tradeData.Add(row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value.ToString());
        }
     }
}

如果我不使用foreach循环，一切都很好，数据网格显示数据。但是当我使用foreach循环时，每个单元格值都返回空/ null。

MessageBox.Show(row.Cells[anyColumn].Value.ToString()); // messagebox shows nothing

这就是为什么只有符合条件的这条线：

if (row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value == null || row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value == DBNull.Value || String.IsNullOrWhiteSpace(row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value.ToString()))

编辑：

这是我创建列并手动设置每个新单元格值的方法：

List<string> tradeData = new List<string>();

string columnSettings = ConfigurationManager.AppSettings["columnSettings"];
string[] columnNameAndFlag = columnSettings.Split(',');

var tradeList = client.getTradeReports(criteria);
tradeGridView.DataSource = tradeList;
int rowCount = tradeGridView.Rows.Count;

foreach (DataGridViewRow row in tradeGridView.Rows)
{
    for (int counter = 0; counter < columnNameAndFlag.Length; counter++)
    {
        if (row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value == null || row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value == DBNull.Value || String.IsNullOrWhiteSpace(row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value.ToString()))
            tradeData.Add("");
        else
        {
            if (columnNameAndFlag[counter].Split('-')[0] == "TransactTime")
                tradeData.Add(dt.AddSeconds(Convert.ToDouble(row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value)).ToLocalTime().ToString());
            else
                tradeData.Add(row.Cells[columnNameAndFlag[counter].Split('-')[0]].Value.ToString());
        }
    }
}

tradeGridView.DataSource = null;
tradeGridView.Columns.Clear();

for (int counter = 0; counter < columnNameAndFlag.Length; counter++)
{
    tradeGridView.Columns.Add(columnNameAndFlag[counter].Split('-')[0], columnNameAndFlag[counter].Split('-')[0]);

    if (columnNameAndFlag[counter].Split('-').Last() == "1")
        tradeGridView.Columns[columnNameAndFlag[counter].Split('-')[0]].Visible = true;
    else
        tradeGridView.Columns[columnNameAndFlag[counter].Split('-')[0]].Visible = false;
}

for (int index = 0; index < rowCount; index++)
    tradeGridView.Rows.Add();

int i = 0;
foreach (DataGridViewRow row in tradeGridView.Rows)
{
    foreach (DataGridViewCell cell in row.Cells)
    {
        cell.Value = tradeData[i];
        i++;
    }
}

Answer 1

你应该写tradeGridView.DataBind（）; tradeGridView.DataSource = tradeList之后的命令;并检查它是否正常工作。

DataGridViewCell值为空，而实际存在

1 个答案: