我有一个一直困扰着我的问题。
在我的代码中，我有以下内容：
private int rowCount
{
get { return (int)ViewState["rowCount"]; }
set { ViewState["rowCount"] = value; }
}
和按钮事件
protected void addRow_Click(object sender, EventArgs e)
{
rowCount = rowCount + 1;
}
然后在Page_Load上我读取了该值并相应地创建了控件。
我理解在Page_Load触发后触发按钮事件，因此在下次回发之前不会更新该值。真正的噩梦。
以下是整个代码：
protected void Page_Load(object sender, EventArgs e)
{
string xmlValue = ""; //To read a value from a database
if (xmlValue.Length > 0)
{
if (!Page.IsPostBack)
{
DataSet ds = XMLToDataSet(xmlValue);
Table dimensionsTable = DataSetToTable(ds);
tablePanel.Controls.Add(dimensionsTable);
DataTable dt = ds.Tables["Dimensions"];
rowCount = dt.Rows.Count;
colCount = dt.Columns.Count;
}
else
{
tablePanel.Controls.Add(DataSetToTable(DefaultDataSet(rowCount, colCount)));
}
}
else
{
if (!Page.IsPostBack)
{
rowCount = 2;
colCount = 4;
}
tablePanel.Controls.Add(DataSetToTable(DefaultDataSet(rowCount, colCount)));
}
}
protected void submit_Click(object sender, EventArgs e)
{
resultsLabel.Text = Server.HtmlEncode(DataSetToStringXML(TableToDataSet((Table)tablePanel.Controls[0])));
}
protected void addColumn_Click(object sender, EventArgs e)
{
colCount = colCount + 1;
}
protected void addRow_Click(object sender, EventArgs e)
{
rowCount = rowCount + 1;
}
public DataSet TableToDataSet(Table table)
{
DataSet ds = new DataSet();
DataTable dt = new DataTable("Dimensions");
ds.Tables.Add(dt);
//Add headers
for (int i = 0; i < table.Rows[0].Cells.Count; i++)
{
DataColumn col = new DataColumn();
TextBox headerTxtBox = (TextBox)table.Rows[0].Cells[i].Controls[0];
col.ColumnName = headerTxtBox.Text;
col.Caption = headerTxtBox.Text;
dt.Columns.Add(col);
}
for (int i = 0; i < table.Rows.Count; i++)
{
DataRow valueRow = dt.NewRow();
for (int x = 0; x < table.Rows[i].Cells.Count; x++)
{
TextBox valueTextBox = (TextBox)table.Rows[i].Cells[x].Controls[0];
valueRow[x] = valueTextBox.Text;
}
dt.Rows.Add(valueRow);
}
return ds;
}
public Table DataSetToTable(DataSet ds)
{
DataTable dt = ds.Tables["Dimensions"];
Table newTable = new Table();
//Add headers
TableRow headerRow = new TableRow();
for (int i = 0; i < dt.Columns.Count; i++)
{
TableCell headerCell = new TableCell();
TextBox headerTxtBox = new TextBox();
headerTxtBox.ID = "HeadersTxtBox" + i.ToString();
headerTxtBox.Font.Bold = true;
headerTxtBox.Text = dt.Columns[i].ColumnName;
headerCell.Controls.Add(headerTxtBox);
headerRow.Cells.Add(headerCell);
}
newTable.Rows.Add(headerRow);
//Add value rows
for (int i = 0; i < dt.Rows.Count; i++)
{
TableRow valueRow = new TableRow();
for (int x = 0; x < dt.Columns.Count; x++)
{
TableCell valueCell = new TableCell();
TextBox valueTxtBox = new TextBox();
valueTxtBox.ID = "ValueTxtBox" + i.ToString() + i + x + x.ToString();
valueTxtBox.Text = dt.Rows[i][x].ToString();
valueCell.Controls.Add(valueTxtBox);
valueRow.Cells.Add(valueCell);
}
newTable.Rows.Add(valueRow);
}
return newTable;
}
public DataSet DefaultDataSet(int rows, int cols)
{
DataSet ds = new DataSet();
DataTable dt = new DataTable("Dimensions");
ds.Tables.Add(dt);
DataColumn nameCol = new DataColumn();
nameCol.Caption = "Name";
nameCol.ColumnName = "Name";
nameCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(nameCol);
DataColumn widthCol = new DataColumn();
widthCol.Caption = "Width";
widthCol.ColumnName = "Width";
widthCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(widthCol);
if (cols > 2)
{
DataColumn heightCol = new DataColumn();
heightCol.Caption = "Height";
heightCol.ColumnName = "Height";
heightCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(heightCol);
}
if (cols > 3)
{
DataColumn depthCol = new DataColumn();
depthCol.Caption = "Depth";
depthCol.ColumnName = "Depth";
depthCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(depthCol);
}
if (cols > 4)
{
int newColCount = cols - 4;
for (int i = 0; i < newColCount; i++)
{
DataColumn newCol = new DataColumn();
newCol.Caption = "New " + i.ToString();
newCol.ColumnName = "New " + i.ToString();
newCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(newCol);
}
}
for (int i = 0; i < rows; i++)
{
DataRow newRow = dt.NewRow();
newRow["Name"] = "Name " + i.ToString();
newRow["Width"] = "Width " + i.ToString();
if (cols > 2)
{
newRow["Height"] = "Height " + i.ToString();
}
if (cols > 3)
{
newRow["Depth"] = "Depth " + i.ToString();
}
dt.Rows.Add(newRow);
}
return ds;
}
public DataSet XMLToDataSet(string xml)
{
StringReader sr = new StringReader(xml);
DataSet ds = new DataSet();
ds.ReadXml(sr);
return ds;
}
public string DataSetToStringXML(DataSet ds)
{
XmlDocument _XMLDoc = new XmlDocument();
_XMLDoc.LoadXml(ds.GetXml());
StringWriter sw = new StringWriter();
XmlTextWriter xw = new XmlTextWriter(sw);
XmlDocument xml = _XMLDoc;
xml.WriteTo(xw);
return sw.ToString();
}
private int rowCount
{
get { return (int)ViewState["rowCount"]; }
set { ViewState["rowCount"] = value; }
}
private int colCount
{
get { return (int)ViewState["colCount"]; }
set { ViewState["colCount"] = value; }
}
编辑：这是我的.aspx，以防你想在VS中尝试。
<asp:Panel ID="tablePanel" runat="server" CssClass="table-panel" />
<asp:Label ID="resultsLabel" runat="server" />
<asp:LinkButton ID="submit" Text="submit" runat="server" onclick="submit_Click" />
<asp:LinkButton ID="addColumn" Text="Add Column" runat="server"
onclick="addColumn_Click" />
<asp:LinkButton ID="addRow" Text="Add Row" runat="server" onclick="addRow_Click" />
提前致谢，
马尔科
答案 0 :(得分：1)
正如我在this other question中所推荐的那样，如果您希望在按钮“Click”事件之后执行某些页面逻辑，请将该代码放入Page_PreRender。
您可以在此处详细了解：ASP.NET page life cycle。
编辑：
在仔细检查代码之后，我看到你添加了东西并创建了新的控件，这在PreRender事件中并不是一个好主意。 相反，将代码放入一个单独的方法。在Page_Load中，检查它是否是回发并在不是时处理大小写。 在按钮'click evnt中，还添加对该新方法的调用。 （因此处理IsPostback == true case）
答案 1 :(得分：1)
好的，我已按照this帖子中的说明解决了问题。
这是我的最终代码 - 如果您需要基于计数器创建动态控件，请随时使用它。
此外，我不介意对整体编码风格的反馈，我总是感谢别人的意见。
protected void Page_Load(object sender, EventArgs e)
{
string xmlValue = ""; //To read a value from a database
if (xmlValue.Length > 0)
{
if (!Page.IsPostBack)
{
DataSet ds = XMLToDataSet(xmlValue);
Table dimensionsTable = DataSetToTable(ds);
tablePanel.Controls.Add(dimensionsTable);
DataTable dt = ds.Tables["Dimensions"];
rowCount = dt.Rows.Count;
colCount = dt.Columns.Count;
}
else
{
tablePanel.Controls.Add(DataSetToTable(DefaultDataSet(rowCount, colCount)));
}
}
else
{
if (!Page.IsPostBack)
{
rowCount = 2;
colCount = 4;
}
else
{
if (GetPostBackControl(this.Page).ID == "addRow")
{
rowCount = rowCount + 1;
}
else if (GetPostBackControl(this.Page).ID == "addColumn")
{
colCount = colCount + 1;
}
}
tablePanel.Controls.Add(DataSetToTable(DefaultDataSet(rowCount, colCount)));
}
}
protected void submit_Click(object sender, EventArgs e)
{
resultsLabel.Text = Server.HtmlEncode(DataSetToStringXML(TableToDataSet((Table)tablePanel.Controls[0])));
}
protected void addColumn_Click(object sender, EventArgs e)
{
}
protected void addRow_Click(object sender, EventArgs e)
{
}
public DataSet TableToDataSet(Table table)
{
DataSet ds = new DataSet();
DataTable dt = new DataTable("Dimensions");
ds.Tables.Add(dt);
//Add headers
for (int i = 0; i < table.Rows[0].Cells.Count; i++)
{
DataColumn col = new DataColumn();
TextBox headerTxtBox = (TextBox)table.Rows[0].Cells[i].Controls[0];
col.ColumnName = headerTxtBox.Text;
col.Caption = headerTxtBox.Text;
dt.Columns.Add(col);
}
for (int i = 0; i < table.Rows.Count; i++)
{
DataRow valueRow = dt.NewRow();
for (int x = 0; x < table.Rows[i].Cells.Count; x++)
{
TextBox valueTextBox = (TextBox)table.Rows[i].Cells[x].Controls[0];
valueRow[x] = valueTextBox.Text;
}
dt.Rows.Add(valueRow);
}
return ds;
}
public Table DataSetToTable(DataSet ds)
{
DataTable dt = ds.Tables["Dimensions"];
Table newTable = new Table();
//Add headers
TableRow headerRow = new TableRow();
for (int i = 0; i < dt.Columns.Count; i++)
{
TableCell headerCell = new TableCell();
TextBox headerTxtBox = new TextBox();
headerTxtBox.ID = "HeadersTxtBox" + i.ToString();
headerTxtBox.Font.Bold = true;
headerTxtBox.Text = dt.Columns[i].ColumnName;
headerCell.Controls.Add(headerTxtBox);
headerRow.Cells.Add(headerCell);
}
newTable.Rows.Add(headerRow);
//Add value rows
for (int i = 0; i < dt.Rows.Count; i++)
{
TableRow valueRow = new TableRow();
for (int x = 0; x < dt.Columns.Count; x++)
{
TableCell valueCell = new TableCell();
TextBox valueTxtBox = new TextBox();
valueTxtBox.ID = "ValueTxtBox" + i.ToString() + i + x + x.ToString();
valueTxtBox.Text = dt.Rows[i][x].ToString();
valueCell.Controls.Add(valueTxtBox);
valueRow.Cells.Add(valueCell);
}
newTable.Rows.Add(valueRow);
}
return newTable;
}
public DataSet DefaultDataSet(int rows, int cols)
{
DataSet ds = new DataSet();
DataTable dt = new DataTable("Dimensions");
ds.Tables.Add(dt);
DataColumn nameCol = new DataColumn();
nameCol.Caption = "Name";
nameCol.ColumnName = "Name";
nameCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(nameCol);
DataColumn widthCol = new DataColumn();
widthCol.Caption = "Width";
widthCol.ColumnName = "Width";
widthCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(widthCol);
if (cols > 2)
{
DataColumn heightCol = new DataColumn();
heightCol.Caption = "Height";
heightCol.ColumnName = "Height";
heightCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(heightCol);
}
if (cols > 3)
{
DataColumn depthCol = new DataColumn();
depthCol.Caption = "Depth";
depthCol.ColumnName = "Depth";
depthCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(depthCol);
}
if (cols > 4)
{
int newColCount = cols - 4;
for (int i = 0; i < newColCount; i++)
{
DataColumn newCol = new DataColumn();
newCol.Caption = "New " + i.ToString();
newCol.ColumnName = "New " + i.ToString();
newCol.DataType = System.Type.GetType("System.String");
dt.Columns.Add(newCol);
}
}
for (int i = 0; i < rows; i++)
{
DataRow newRow = dt.NewRow();
newRow["Name"] = "Name " + i.ToString();
newRow["Width"] = "Width " + i.ToString();
if (cols > 2)
{
newRow["Height"] = "Height " + i.ToString();
}
if (cols > 3)
{
newRow["Depth"] = "Depth " + i.ToString();
}
dt.Rows.Add(newRow);
}
return ds;
}
public DataSet XMLToDataSet(string xml)
{
StringReader sr = new StringReader(xml);
DataSet ds = new DataSet();
ds.ReadXml(sr);
return ds;
}
public string DataSetToStringXML(DataSet ds)
{
XmlDocument _XMLDoc = new XmlDocument();
_XMLDoc.LoadXml(ds.GetXml());
StringWriter sw = new StringWriter();
XmlTextWriter xw = new XmlTextWriter(sw);
XmlDocument xml = _XMLDoc;
xml.WriteTo(xw);
return sw.ToString();
}
private int rowCount
{
get { return (int)ViewState["rowCount"]; }
set { ViewState["rowCount"] = value; }
}
private int colCount
{
get { return (int)ViewState["colCount"]; }
set { ViewState["colCount"] = value; }
}
public static Control GetPostBackControl(Page page)
{
Control control = null;
string ctrlname = page.Request.Params.Get("__EVENTTARGET");
if (ctrlname != null && ctrlname != string.Empty)
{
control = page.FindControl(ctrlname);
}
else
{
foreach (string ctl in page.Request.Form)
{
Control c = page.FindControl(ctl);
if (c is System.Web.UI.WebControls.Button)
{
control = c;
break;
}
}
}
return control;
}
答案 2 :(得分：0)
移动此代码：
tablePanel.Controls.Add(DataSetToTable(DefaultDataSet(rowCount, colC....
在prerender事件中，在按钮单击触发后使表绑定到其数据。