如何使用Razor / Webforms语法访问属性内的属性

Question

I'm trying to set a maximum length limit in a text area using a regex validator (if there is a better way to do this, please let me know). This is an ASP.Net webforms user control. The current code I have is

<asp:Panel ID="labeledTextBox" runat="server">
    <asp:Label ID="label" CssClass="label" ClientIDMode="Static" runat="server"/>
    <asp:TextBox ID="textBox" CssClass="labeledTextBox" TextMode="MultiLine" ClientIDMode="Static" runat="server"/>
    <asp:Label ID="textBoxLengthLabel" CssClass="textBoxLengthLabel" ClientIDMode="Static" runat="server">Maximum <%= MaxLength %> characters</asp:Label>
    <asp:RegularExpressionValidator ID="textboxLengthValidator" Display="Dynamic" ControlToValidate="textBox" ValidationExpression="^[\s\S]{0,<%= MaxLength %>}$" ErrorMessage="Test Message" ClientIDMode="Static" runat="server" />
</asp:Panel>

MaxLength is defined in the codebehind file as

public int MaxLength { get; set; }

The value I set shows up in the textBoxLengthLabel properly as, for example, Maximum 500 characters .

However, it is taken literally in the attribute for the validator. The markup on the client side is

<SPAN id=textboxLengthValidator
      style="COLOR: red; DISPLAY: inline"
      controltovalidate="textBox"
      errormessage="Test Message"
      validationexpression="^[\s\S]{0,<%= MaxLength %>}$"
      isvalid="false"
      display="Dynamic">Test Message</SPAN>

How can I use the property in the code-behind file in the attribute?

Answer 1

在页面加载或提交后的代码中，您只需添加属性

textBox.Attributes.Add("maxlength",  MaxLength.ToString());