从代码隐藏创建aspx文本框 [英] Creating aspx textbox from codebehind

问题描述

如何在C#中从后面的代码创建aspx文本框，以及如何在后面的代码中访问其值?我按如下操作，但是在每个帖子背面的文本框都被清除了.我需要将其值保留在回发上.

how can I create aspx textbox from code behind in C# and how to access its value in code behind ? I do as follows but on every post backs text box is getting cleared. I need to keep its values on post backs.

TextBox txt = new TextBox();
txt.ID = "strtxtbox";
txt.CssClass = "CSS1";
StringBuilder sb = new StringBuilder();
StringWriter writer = new StringWriter(sb);
HtmlTextWriter htmlWriter = new HtmlTextWriter(writer);
txt.RenderControl(htmlWriter);

//lbl is an aspx label
lbl.text += @"<td style='width: 5%;'>" + sb.ToString() + "</td>";

然后我按如下方式访问文本框值

And I access text box value as follows

string tb = Request.Form["strtxtbox"].ToString();

推荐答案

您可以从创建TextBox控件开始.必须在 Init()( Page_Init())或 PreInit()( Page_PreInit())方法，则无论 Page.IsPostBack 是什么，您都必须这样做.这样会将元素放在 ViewState 加载之前的页面上，并允许您在回发时检索值.

You can start by creating the TextBox control. It must be done in the Init() (Page_Init()) or PreInit() (Page_PreInit()) method, and you have to do it regardless of Page.IsPostBack. This will put the element on the page before the ViewState is loaded, and will allow you to retrieve the value on postback.

var textBox = new TextBox();

然后，您应该在其上设置一些属性，包括ID，以便以后查找:

Then you should set a few properties on it, including an ID so you can find it later:

textBox.ID = "uxTxtSomeName";
textBox.MaxLength = 10; // maximum input length
textBox.Columns = 20; // character width of the textbox
etc...

然后，您需要将其添加到页面上的适当容器中( Page ，或者您希望其出现在其中的任何控件):

Then you need to add it to an appropriate container on the page (Page, or whichever control you want it to appear within):

parentControl.Controls.Add(textBox);

然后在回发时，可以使用父级的 FindControl()函数:

Then on post back, you can retrieve the value, probably in the Load() method (Page_Load()) using the parent's FindControl() function:

var input = (parentControl.FindControl("uxTxtSomeName") as TextBox).Text;

注意:内置的 FindControl()仅迭代直接子级.如果要搜索嵌套服务器控件的整个树，则可能需要实现自己的递归 FindControl()函数.虽然[so]上有一百万个递归 FindControl()函数的示例，所以我将由您自己决定.

Note: The built-in FindControl() only iterates through immediate children. If you want to search through the entire tree of nested server controls, you may need to implement your own recursive FindControl() function. There are a million and one examples of recursive FindControl() functions on [so] though, so I'll leave that up to you.

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