Asp.net文本框，Multiline属性为true，不支持max lenght值，为什么？

It is strange Asp.net Text box with multi line attribute does not support max lenth property. we need to manage it by writing customized java script Code.

奇怪的是，具有多行属性的Asp.net文本框不支持max lenth属性。我们需要通过编写自定义的java脚本代码来管理它。

2 个解决方案

#1

because the textbox-mode multiline is rendered as textarea, and the textarea does not contain a maxlength property.

因为textbox-mode多线渲染为textarea，而textarea不包含maxlength属性。

yes, apply a javascript, and, to be sure add also some server-side check for the length (if the client disables javascript)

是的，应用一个JavaScript，并确保添加一些服务器端检查的长度（如果客户端禁用JavaScript）

#2

TextBox, when multi-line, renders a TextArea that does not contain a MaxLength property.

TextBox，当多行时，呈现不包含MaxLength属性的TextArea。

TextBox control should act different as for the output of the MaxLength property depending on the TextMode property. If it's single-line, render MaxLength, if it's not, render a JavaScript. I consider it a bad behavior or maybe a bug.

TextBox控件的行为应与MaxLength属性的输出不同，具体取决于TextMode属性。如果它是单行，则渲染MaxLength，如果不是，则渲染JavaScript。我认为这是一个不好的行为或可能是一个错误。

In these cases when you are curious you can always take a look at Microsoft's code with Reflector.

在这些情况下，当您感到好奇时，您总是可以使用Reflector查看Microsoft的代码。

Here's the code snippet for MaxLength property rendering in the AddAttributesToRender method:

这是AddAttributesToRender方法中MaxLength属性呈现的代码片段：

int maxLength = this.MaxLength;
    if (maxLength > 0)
    {
        writer.AddAttribute(HtmlTextWriterAttribute.Maxlength, maxLength.ToString(NumberFormatInfo.InvariantInfo));
    }
    maxLength = this.Columns;
    if (maxLength > 0)
    {
        writer.AddAttribute(HtmlTextWriterAttribute.Size, maxLength.ToString(NumberFormatInfo.InvariantInfo));
    }

#1