“<” in a text box in ASP.NET --> how to allow it?

Question

I have a textfield which displays a string which contains < and >. The code throws an error because of that. How can I allow the usage of those chars in my textfield?

Answer 1

The easiest solution is to disable request validation in single pages

<%@ Page ... ValidateRequest="false" %>

but don't forget to enable requestValidationMode="2.0"

   ...
   

This solution could espose some threats.

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Another smart solution is to replace via javascript text written by user to make it safe for validation: is considere dangerous, but < tag> is considered safe!

A javascript replacement can solve the problem.

function validateTxt() {
    $("textarea, input[type='text']").change(function () {
      html = $(this).val(); //get the value
      //.replace("a" , "b")  works only on first occurrence of "a"
      html = html.replace(/< /g, "<"); //before: if there's space after < remove
      html = html.replace(/