【发布时间】：2014-08-07 21:58:09
【问题描述】：
我在工作中的一个项目的要求方面遇到问题。我正在做的是将数据表绑定到 DataGridView(DGV) 的数据源。然后，我遍历 DataGridView 并检查单元格的值是否为 1 * 或 2 **，并使用工具提示和红色背景格式化这些单元格。如果我使用按钮事件来触发这一切都很好。但是，如果我希望在使用 DataBindingComplete 事件加载表单时自动发生这种情况，则它无法正常工作。问题是 DataBindingComplete 多次触发。我读了this SO question，它给了我几个尝试的选择，但没有一个奏效。代码如下：
public partial class TestForm2 : Form
{
private DataTable dt;
private int methodCalls = 0;
private bool isFormatted = false;
public TestForm2()
{
InitializeComponent();
buildDataTable();
dataGridView1.DataBindingComplete += dataGridView1_DataBindingComplete;
}
private void TestForm2_Load(object sender, EventArgs e)
{
bindData();
}
private void button1_Click(object sender, EventArgs e)
{
formatDataGridView();
}
private void bindData()
{
dataGridView1.DataSource = dt;
}
private void dataGridView1_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
{
//If this code is commented out the program will work just fine
//by just clicking the button
//This was added to prevent formatDataGridView from executing more
//than once. Even though I unreg and rereg the event handler, the
//method was still being called 3 - 4 times. This successfully
//prevented that but only the *'s were removed and no red back color
//added to the cells.
if(!isFormatted)
{
formatDataGridView();
}
}
private void buildDataTable()
{
dt = new DataTable();
dt.Columns.Add("col1");
dt.Columns.Add("col2");
dt.Columns.Add("col3");
dt.Columns.Add("col4");
Random randNum = new Random();
for(int i = 0; i < 10; i++)
{
DataRow dr;
object[] rowItems = new object[dt.Columns.Count];
for(int j = 0; j < dt.Columns.Count; j++)
{
int number = randNum.Next(1, 20);
if(number % 7 == 0)
{
rowItems[j] = number + "*";
}
else if(number % 5 == 0)
{
rowItems[j] = number + "**";
}
else
{
rowItems[j] = number;
}
}
dr = dt.NewRow();
dr.ItemArray = rowItems;
dt.Rows.Add(dr);
}
}
private void formatDataGridView()
{
// I noticed that I needed to unregister the event handler to
// prevent DataBindingComplete from firing during the format
dataGridView1.DataBindingComplete -= dataGridView1_DataBindingComplete;
foreach(DataGridViewRow row in dataGridView1.Rows)
{
string originalCell;
string reformattedCell;
if(row.Cells["col1"].Value != null)
{
originalCell = row.Cells["col1"].Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
row.Cells["col1"].Value = reformattedCell;
row.Cells["col1"].Style.BackColor = Color.Red;
row.Cells["col1"].ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
row.Cells["col1"].Value = reformattedCell;
row.Cells["col1"].Style.BackColor = Color.Red;
row.Cells["col1"].ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
if (row.Cells["col2"].Value != null)
{
originalCell = row.Cells["col2"].Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
row.Cells["col2"].Value = reformattedCell;
row.Cells["col2"].Style.BackColor = Color.Red;
row.Cells["col2"].ToolTipText = "Divisible by 5";
}
if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
row.Cells["col2"].Value = reformattedCell;
row.Cells["col2"].Style.BackColor = Color.Red;
row.Cells["col2"].ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
if (row.Cells["col3"].Value != null)
{
originalCell = row.Cells["col3"].Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
row.Cells["col3"].Value = reformattedCell;
row.Cells["col3"].Style.BackColor = Color.Red;
row.Cells["col3"].ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
row.Cells["col3"].Value = reformattedCell;
row.Cells["col3"].Style.BackColor = Color.Red;
row.Cells["col3"].ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
if (row.Cells["col4"].Value != null)
{
originalCell = row.Cells["col4"].Value.ToString();
if (originalCell.Count(c => c == '*') == 2)
{
reformattedCell = originalCell.Replace("**", "");
row.Cells["col4"].Value = reformattedCell;
row.Cells["col4"].Style.BackColor = Color.Red;
row.Cells["col4"].ToolTipText = "Divisible by 5";
}
else if (originalCell.Count(c => c == '*') == 1)
{
reformattedCell = originalCell.Replace("*", "");
row.Cells["col4"].Value = reformattedCell;
row.Cells["col4"].Style.BackColor = Color.Red;
row.Cells["col4"].ToolTipText = "Divisible by 7";
}
else
{
//do nothing
}
}
}
// Reregistering the event handler
dataGridView1.DataBindingComplete += dataGridView1_DataBindingComplete;
isFormatted = true;
methodCalls++;
MessageBox.Show("Method Calls: " + methodCalls);
}
}
我不确定如何解决这个问题，但必须有办法。直到最近我才对 DataBindingComplete 不熟悉，所以我肯定会在这里学到一些东西。感谢大家的帮助，帮助我学习新东西！
【问题讨论】：
-
尝试使用 CellFormatting 事件。
-
我认为出错的是，在 DataBindEvent 期间，您正在更改网格中的一些值。然后将这些更改保存在 DataSource 中，之后 DataSource 再次与新值绑定，重新触发 DataBindEvent。
-
@BartvanderDrift 我相信是这样。如果我没有通过在我的 formatDataGridView 方法中声明 dataGridView1.DataBindingComplete -= dataGridView1_DataBindingComplete 来取消注册 dataGridView1_DataBindingComplete 事件处理程序，则计数器 methodCalls 报告该方法被调用的次数与所做更改的次数一样多。但是，我通过取消注册事件处理程序来阻止这种情况的发生，以防止这些更改触发事件。我还放了一个 bool isFormatted，一旦调用该方法就会设置为 true，条件 if(!isFormatted) 也可以防止这种情况发生
-
所以尽管从事件中解除绑定，但 dataGridView1_DataBindingComplete 函数被多次调用？
-
@LarsTech 我可能有一个使用您的方法的解决方案。我只需要重写一些东西来测试它。感谢您的意见！
标签： c# data-binding datagridview event-handling