获取动态下拉列表值。 [英] Get the dynamic dropdownlist value.
本文介绍了获取动态下拉列表值。的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我编写了动态创建表的代码。该表包含一个文本框和一个下拉列表。当我选择像Splitter1：5这样的下拉列表而不是表格行创建5时，我尝试根据选定的下拉列表值创建表格。第一次成功完成，当我第二次尝试第二次没有得到下拉列表的值。我正在分享我的代码，请帮助我。
我尝试过：
aspx
<％@ Page Language =C＃AutoEventWireup =trueCodeFile =testform.aspx.csInherits =testform％>
<！DOCTYPE html>
< html xmlns =http://www.w3.org/1999/xhtml>
< head runat =server>
< title>< / title>
< / head>
< body>
< form id =form1runat =server>
< div>
< asp：DropDownList ID =ddlTextBoxesrunat =server>
< asp：ListItem Value =2Text =Splitter1：2/>
< asp：ListItem Value =4Text =Splitter1：4/>
< asp：ListItem Value =8Text =Splitter1：8/>
< asp：ListItem Value =1Text =Joint/>
< asp：ListItem Value =0Text =OLT/>
< / asp：DropDownList>
< asp：Button ID =btnAddrunat =serverText =AddOnClick =btnAdd_Click/>< br />
< asp：Panel ID =containerrunat =serverVisible =false> < asp：Button ID =btnSubmitrunat =serverText =ProcessOnClick =Submit/>< / asp：Panel>
< / div>
< / form>
< / body>
< / html>
使用System;
使用System.Collections;
使用System.Collections.Generic;
使用System.Data;
使用System.Linq;
使用System.Web;
使用System.Web.UI;
使用System.Web.UI.WebControls;
public partial class testform：System.Web.UI.Page
{
DropDownList DDL; int i;
ArrayList arry_value = new ArrayList（）; object [] obj;
专家组;
protected void Page_Load（object sender，EventArgs e）
{
// ViewState [droplist] = obj;
}
protected void btnAdd_Click（object sender，EventArgs e）
{
int numOfTxt = Convert.ToInt32（ddlTextBoxes.SelectedItem） 。值）;
// DataTable dt = new DataTable（）;
//dt.Columns.Add(\"First Textbox）;
// dt.Columns.Add（Dropdownlist）;
// dt.Columns.Add（Last Textbox）;
var table = new Table（）;
for（i = 0; i< numOfTxt; i ++）
{
var row = new TableRow（）;
var cell = new TableCell（）;
// var thr = new TableHeaderRow（）;
// var heading = new TableHeaderCell（）;
// TableHeaderCell thPNumber = new TableHeaderCell（）;
// cell.Attributes.Add（runat，server）;
TextBox textbox = new TextBox（）;
textbox.ID =Textbox+ i;
textbox.Text =text+ i;
textbox.Width = new Unit（180）;
TextBox textbox1 = new TextBox（）;
textbox1.ID =Textbox1+ i;
textbox1.Text =text1+ i;
textbox1.Width = new Unit（180）;
DDL = new DropDownList（）;
DDL.ID =DDL1+ i;
DDL.Items.Add（Select Splitter）;
DDL.Items.Add（new ListItem（Splitter1：2，2））;
DDL.Items.Add（new ListItem（Splitter1：4，4））;
DDL.Items.Add（new ListItem（Splitter1：8，8））;
DDL.Items.Add（new ListItem（Joint，1））;
DDL.Items.Add（new ListItem（ONT，0））;
DDL.AutoPostBack = true;
DDL.SelectedIndexChanged + = new System.EventHandler（DDL_SelectedIndexChanged）;
cell.Controls.Add（textbox1）;
cell.Controls.Add（DDL）;
cell.Controls.Add（textbox）;
row.Cells.Add（cell）;
table.Rows.Add（row）;
arry_value.Add（DDL.ID）;
foreach（arry_value中的对象obj）
{
var idcollection = new string [] {obj.ToString（）};
}
}
pn = new Panel（）;
pn.ID =pan+ i + 1;
this.form1.Controls.Add（pn）;
container.Visible = true;
Button btnSubmit = new Button（）;
btnSubmit.ID =btnSubmit;
btnSubmit.Text =Processone;
btnSubmit.Click + = new System.EventHandler（Submit）;
container.Controls.Add（table）;
//pn.Controls.Add(btnSubmit）;
// container.Controls.AddAt（0，table）;
}
protected void DDL_SelectedIndexChanged（object sender，EventArgs e）
{
ScriptManager.RegisterClientScriptBlock（this，this.GetType（），alertMessage ，警报（'记录插入成功'），真实）;
}
protected void提交（对象发件人，EventArgs e）
{
//学生专栏=（学生）ViewState [CurrentStudent];
// DropDownList ddl =（DropDownList）container.FindControl（DDL1+ i）;
int numOfTxt = 5;
Label lb = new Label（）;
//lb.Text = DDL.SelectedValue.ToString（）;
// int numOfTxt = Convert.ToInt32（lb）;
string drpvalue;
for（int j = 0; j< Convert.ToInt32（ddlTextBoxes.SelectedItem.Value）; j ++）
{
drpvalue =DDL12+ i +。SelectedItem.Value ;
// int te = Convert.ToInt32（drpvalue）;
// numOfTxt + = Convert.ToInt32（DDL120.SelectedItem.Value）;
}
// int numOfTxt = Convert.ToInt32（ddlTextBoxes.SelectedItem.Value）;
var table = new Table（）;
DataTable dt = new DataTable（）;
for（int i = 0; i< numOfTxt; i ++）
{
var row = new TableRow（）;
var cell = new TableCell（）;
// dt.Columns.Add（TextOne1）;
cell.Attributes.Add（runat，server）;
TextBox textbox = new TextBox（）;
textbox.ID =Textbox+ i;
textbox.Text =text+ i;
textbox.Width = new Unit（180）;
TextBox textbox1 = new TextBox（）;
textbox1.ID =Textbox1+ i;
textbox1.Text = textbox1.Text;
textbox1.Width = new Unit（180）;
DropDownList DDLs = new DropDownList（）;
DDLs.ID =DDL12+ i;
// count = Convert.ToInt32（DDL.ID =DDL12+ i）;
DDLs.Items.Add（Select Splitter）;
DDLs.Items.Add（new ListItem（Splitter1：2，2））;
DDLs.Items.Add（new ListItem（Splitter1：4，4））;
DDLs.Items.Add（new ListItem（Splitter1：8，8））;
DDLs.Items.Add（new ListItem（Joint，1））;
DDLs.Items.Add（new ListItem（ONT，0））;
//DDLs.AutoPostBack = true;
// DDLs.TextChanged + = dropDown_TextChanged;
// dt.Rows.Add（textbox1）;
cell.Controls.Add（textbox1）;
// dt.Columns.Add（ListDropdown）;
cell.Controls.Add（DDLs）;
// dt.Columns.Add（Textbodx）;
cell.Controls.Add（textbox）;
row.Cells.Add（cell）;
table.Rows.Add（row）;
}
按钮btnSubmit = new Button（）;
btnSubmit.ID =btnSubmit;
btnSubmit.Text =过程;
btnSubmit.Click + = new System.EventHandler（Submit）;
小组平底锅=新小组（）;
pans.ID =panss;
this.form1.Controls.Add（pans）;
pans.Controls.AddAt（0，table）;
pans.Controls.Add（btnSubmit）;
pans.Visible = true;
//pn.Visible = true;
}
}
解决方案
如上所述，动态添加的控件应该是在每个回发上重新创建以将其保留在页面上。请参阅： ASP.Net持续动态控制：动态控件在ASP.Net中的PostBack后消失
这里有一个关于如何动态生成TextBox行的快速示例控制到表。
private int numOfRows = 0 ;
private int numOfColumns = 0 ;
private void GenerateTable（ int colsCount， int rowsCount）{
// < span class =code-comment>创建表并将其添加到页面
表table = new Table（）;
table.ID = Table1;
Page.Form.Controls.Add（table）;
// 现在遍历表并添加控件
for （ int i = 0 ; i < rowsCount; i ++）{
TableRow row = new TableRow（）;
for （ int j = 0 ; j < colsCount; j ++）{
TableCell cell = new TableCell（） ;
TextBox tb = new TextBox（）;
// 为每个添加的TextBox设置唯一ID
tb.ID = TextBoxRow _ + i + Col _ + j;
// 将控件添加到TableCell
cell.Controls.Add（ TB）;
// 将TableCell添加到TableRow
row.Cells.Add（细胞）;
}
// 将TableRow添加到表中
table.Rows.Add（row）;
}
}
上面的代码只是创建一个空白表并将其添加到表单中。然后根据rowsCount和的值，用。TextBoxes的列和行填充表格。 colsCount
现在，您可以在Page_Load事件上调用上面的方法来重新创建表回发时。
<前lang =c＃> 受保护 void Page_Load（ object sender，EventArgs e）{
// 两个参数全局声明
GenerateTable（numOfColumns，numOfRows）;
}
然后你可以在Button Click事件中调用方法GenerateTable（），如下所示：
受保护 void Button1_Click（ object sender，EventArgs e）{
// 检查输入是否为数字
if （ int .TryParse（TextBox1 .Text.Trim（）， out numOfColumns）&& int .TryParse（TextBox2.Text。修剪（）， out numOfRows））
{
// 根据输入生成表
GenerateTable（numOfColumns，numOfRows）;
// 将当前行和列存储在ViewState中作为回发时的参考值
ViewState [ cols] = numOfColumns;
ViewState [ rows] = numOfRows;
}
else
{
Response.Write（ 值不是数字！）;
}
}
就本例而言，我们使用了两个TextBoxes，以便您能够测试numOfColumns和numOfRows参数的值。在您的情况下，您可以绕过它并使用所选DropDownList的值。例如：
numOfColumns = 1 ;
numOfRows = Convert.ToInt32（ddlTextBoxes.SelectedItem.Value;
GenerateTable（numOfColumns，numOfRows）;
最后，既然我们已经动态地用TextBoxes创建了我们的表，我们可以获取输入的值来自动态TextBox使用Request.Form集合。这是下面的代码块。
protected void Button2_Click（ object sender，EventArgs e）{
// 检查如果ViewState值为null
if （ViewState [ cols]！= null && ViewState [ rows]！= null ）
{
// 在页面中查找表
表table =（表）Page.FindControl（ Table1）;
if （table！= null ）
{
// 重新创建包含当前行和列的表
GenerateTable（ int .Parse（ViewState [ cols]。ToString（） ）， int .Parse（ViewState [ rows< /跨度>]的ToString（）））。
// 现在我们可以遍历Table的行和列并获取值来自TextBoxes
for （ int i = 0 ; i < int .Parse（ViewState [ rows]。ToString（））; i ++）
{
for （ int j = 0 ; j < int .Parse（ViewState [ cols]。ToString（））; j ++）
{
// 打印输入的值
if （Request.Form [ TextBoxRow _ + i + Col _ + j]！= string .Empty）
{
Response.Write（Request.Form [ TextBoxRow _ + i + Col _ + j] + < BR />）;
}
}
}
}
}
}
就是这样。希望有所帮助。
如果您还在寻找GridView解决方案，您可以查看我的文章： 在GridView中动态添加和删除行并一次保存所有行 [ ^ ]
I have written code for dynamically creating a table. The table contains a textbox and a Dropdownlist. I trying to create the table based on selected dropdownlist value when I select dropdown list like "Splitter1:5" than Table row will creating 5 . First time it has done successfully, when I try to second time I did not get the value of dropdown list. i am sharing my code please help me.
What I have tried:
aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="testform.aspx.cs" Inherits="testform" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DropDownList ID="ddlTextBoxes" runat="server">
<asp:ListItem Value="2" Text="Splitter1:2" />
<asp:ListItem Value="4" Text="Splitter1:4" />
<asp:ListItem Value="8" Text="Splitter1:8" />
<asp:ListItem Value="1" Text="Joint" />
<asp:ListItem Value="0" Text="OLT" />
</asp:DropDownList>
<asp:Button ID="btnAdd" runat="server" Text="Add" OnClick="btnAdd_Click" /><br />
<asp:Panel ID="container" runat="server" Visible="false"> <asp:Button ID="btnSubmit" runat="server" Text="Process" OnClick="Submit" /></asp:Panel>
</div>
</form>
</body>
</html>
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class testform : System.Web.UI.Page
{
DropDownList DDL; int i;
ArrayList arry_value = new ArrayList(); object[] obj;
Panel pn;
protected void Page_Load(object sender, EventArgs e)
{
//ViewState["droplist"] = obj;
}
protected void btnAdd_Click(object sender, EventArgs e)
{
int numOfTxt = Convert.ToInt32(ddlTextBoxes.SelectedItem.Value);
// DataTable dt = new DataTable();
//dt.Columns.Add("First Textbox");
// dt.Columns.Add("Dropdownlist");
// dt.Columns.Add("Last Textbox");
var table = new Table();
for (i = 0; i < numOfTxt; i++)
{
var row = new TableRow();
var cell = new TableCell();
// var thr = new TableHeaderRow();
// var heading = new TableHeaderCell();
//TableHeaderCell thPNumber = new TableHeaderCell();
// cell.Attributes.Add("runat", "server");
TextBox textbox = new TextBox();
textbox.ID = "Textbox" + i;
textbox.Text = "text" + i;
textbox.Width = new Unit(180);
TextBox textbox1 = new TextBox();
textbox1.ID = "Textbox1" + i;
textbox1.Text = "text1" + i;
textbox1.Width = new Unit(180);
DDL = new DropDownList();
DDL.ID = "DDL1" + i;
DDL.Items.Add("Select Splitter");
DDL.Items.Add(new ListItem("Splitter1:2", "2"));
DDL.Items.Add(new ListItem("Splitter1:4", "4"));
DDL.Items.Add(new ListItem("Splitter1:8", "8"));
DDL.Items.Add(new ListItem("Joint", "1"));
DDL.Items.Add(new ListItem("ONT", "0"));
DDL.AutoPostBack = true;
DDL.SelectedIndexChanged += new System.EventHandler(DDL_SelectedIndexChanged);
cell.Controls.Add(textbox1);
cell.Controls.Add(DDL);
cell.Controls.Add(textbox);
row.Cells.Add(cell);
table.Rows.Add(row);
arry_value.Add(DDL.ID);
foreach (object obj in arry_value)
{
var idcollection = new string[] { obj.ToString() };
}
}
pn = new Panel();
pn.ID = "pan" + i + 1;
this.form1.Controls.Add(pn);
container.Visible = true;
Button btnSubmit = new Button();
btnSubmit.ID = "btnSubmit";
btnSubmit.Text = "Processone";
btnSubmit.Click += new System.EventHandler(Submit);
container.Controls.Add(table);
//pn.Controls.Add(btnSubmit);
// container.Controls.AddAt(0, table);
}
protected void DDL_SelectedIndexChanged(object sender, EventArgs e)
{
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "alertMessage", "alert('Record Inserted Successfully')", true);
}
protected void Submit(object sender, EventArgs e)
{
//Student stud = (Student)ViewState["CurrentStudent"];
//DropDownList ddl = (DropDownList)container.FindControl("DDL1"+i);
int numOfTxt = 5;
Label lb = new Label();
//lb.Text = DDL.SelectedValue.ToString();
//int numOfTxt = Convert.ToInt32(lb);
string drpvalue;
for (int j = 0; j < Convert.ToInt32(ddlTextBoxes.SelectedItem.Value); j++)
{
drpvalue = "DDL12" + i + ".SelectedItem.Value";
//int te = Convert.ToInt32(drpvalue);
// numOfTxt += Convert.ToInt32(DDL120.SelectedItem.Value);
}
//int numOfTxt = Convert.ToInt32(ddlTextBoxes.SelectedItem.Value);
var table = new Table();
DataTable dt = new DataTable();
for (int i = 0; i < numOfTxt; i++)
{
var row = new TableRow();
var cell = new TableCell();
// dt.Columns.Add("TextOne1");
cell.Attributes.Add("runat", "server");
TextBox textbox = new TextBox();
textbox.ID = "Textbox" + i;
textbox.Text = "text" + i;
textbox.Width = new Unit(180);
TextBox textbox1 = new TextBox();
textbox1.ID = "Textbox1" + i;
textbox1.Text = textbox1.Text;
textbox1.Width = new Unit(180);
DropDownList DDLs = new DropDownList();
DDLs.ID = "DDL12" + i;
// count= Convert.ToInt32( DDL.ID = "DDL12" + i);
DDLs.Items.Add("Select Splitter");
DDLs.Items.Add(new ListItem("Splitter1:2", "2"));
DDLs.Items.Add(new ListItem("Splitter1:4", "4"));
DDLs.Items.Add(new ListItem("Splitter1:8", "8"));
DDLs.Items.Add(new ListItem("Joint", "1"));
DDLs.Items.Add(new ListItem("ONT", "0"));
//DDLs.AutoPostBack = true;
// DDLs.TextChanged += dropDown_TextChanged;
// dt.Rows.Add(textbox1);
cell.Controls.Add(textbox1);
// dt.Columns.Add("ListDropdown");
cell.Controls.Add(DDLs);
// dt.Columns.Add("Textbodx");
cell.Controls.Add(textbox);
row.Cells.Add(cell);
table.Rows.Add(row);
}
Button btnSubmit = new Button();
btnSubmit.ID = "btnSubmit";
btnSubmit.Text = "Process";
btnSubmit.Click += new System.EventHandler(Submit);
Panel pans = new Panel();
pans.ID = "panss";
this.form1.Controls.Add(pans);
pans.Controls.AddAt(0, table);
pans.Controls.Add(btnSubmit);
pans.Visible = true;
//pn.Visible = true;
}
} 解决方案
As mentioned, dynamically added controls should be recreated on each postbacks to retain them on the page. See: ASP.Net Persist Dynamic Controls: Dynamic Controls disappear after PostBack in ASP.Net
Here's a quick example on how to dynamically generate rows ofTextBoxcontrols to atable.
private int numOfRows = 0; private int numOfColumns = 0; private void GenerateTable(int colsCount, int rowsCount){ //Creat the Table and Add it to the Page Table table = new Table(); table.ID = "Table1"; Page.Form.Controls.Add(table); // Now iterate through the table and add your controls for (int i = 0; i < rowsCount; i++){ TableRow row = new TableRow(); for (int j = 0; j < colsCount; j++){ TableCell cell = new TableCell(); TextBox tb = new TextBox(); // Set a unique ID for each TextBox added tb.ID = "TextBoxRow_" + i + "Col_" + j; // Add the control to the TableCell cell.Controls.Add(tb); // Add the TableCell to the TableRow row.Cells.Add(cell); } // Add the TableRow to the Table table.Rows.Add(row); } }
The code above simply creates a blank table and add it to the form. It then fill the table with columns and rows ofTextBoxesbased from the values ofrowsCountandcolsCount.
Now, you can call the method above onPage_Loadevent to recreate thetablewhen it postbacks.
protected void Page_Load(object sender, EventArgs e){ // the two paramters are declared globally GenerateTable(numOfColumns, numOfRows); }
You can then call the method GenerateTable() at Button Click event like this:
protected void Button1_Click(object sender, EventArgs e){ //Check if the inputs are numbers if (int.TryParse(TextBox1.Text.Trim(), out numOfColumns) && int.TryParse(TextBox2.Text.Trim(), out numOfRows)) { //Generate the Table based from the inputs GenerateTable(numOfColumns, numOfRows); //Store the current Rows and Columns In ViewState as a reference value when it post backs ViewState["cols"] = numOfColumns; ViewState["rows"] = numOfRows; } else { Response.Write("Values are not numeric!"); } }
Just for this example, we've use twoTextBoxesfor you to be able to test the values ofnumOfColumnsandnumOfRowsparameters. In your case, you could bypass it and use the value of the DropDownList selected. For example:
numOfColumns = 1; numOfRows = Convert.ToInt32(ddlTextBoxes.SelectedItem.Value; GenerateTable(numOfColumns, numOfRows);
Finally, since we're done creating ourTablewithTextBoxesdynamically, we can grab the values entered from the dynamicTextBoxusingRequest.Formcollection. Here’s the code block below.
protected void Button2_Click(object sender, EventArgs e){ //Check if ViewState values are null if (ViewState["cols"] != null && ViewState["rows"] != null) { //Find the Table in the page Table table = (Table)Page.FindControl("Table1"); if (table != null) { //Re create the Table with the current rows and columns GenerateTable(int.Parse(ViewState["cols"].ToString()), int.Parse(ViewState["rows"].ToString())); // Now we can loop through the rows and columns of the Table and get the values from the TextBoxes for (int i = 0; i < int.Parse(ViewState["rows"].ToString()) ; i++) { for (int j = 0; j < int.Parse(ViewState["cols"].ToString()); j++) { //Print the values entered if (Request.Form["TextBoxRow_" + i + "Col_" + j] != string.Empty) { Response.Write(Request.Form["TextBoxRow_" + i + "Col_" + j] + "<BR/>"); } } } } } }
That's it. Hope that helps.
If you are also looking for aGridViewsolution, you can check my article about: Dynamically Adding and Deleting Rows in GridView and Saving All Rows at Once[^]
这篇关于获取动态下拉列表值。的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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