RegularExpression data annotation: Regex that matches all content that is not an HTML tag

0
votes

There is a need for client unobtrusive validation on the textbox to warn user that he types invalid symbols. I want to use RegularExpression in data annotation, somethimg like this:

[Required]
[Display(Name = "RecordBody", ResourceType = typeof(Resources))]
[RegularExpression(@"(\<(/?[^\>]+)\>)", ErrorMessageResourceType = typeof(ValidationErrors), ErrorMessageResourceName = "DisallowHtml")]
[StringLength(8191, ErrorMessageResourceType = typeof(ValidationErrors), ErrorMessageResourceName = "TooLongEntry")]
public string Description { get; set; }

A regular expression is used on server side to validate user input and is used on client side in Javascript regular expression:

<textarea cols="20" data-val="true" data-val-disallowhtml="Поле Текст записи содержит недопустимые символы" data-val-disallowhtml-pattern="(\<(/?[^\>]+)\>)" data-val-length="Введено слишком много символов. Допустимо: 8191" data-val-length-max="8191" data-val-required="Требуется поле Текст записи." id="Description" name="Description" rows="2"></textarea>

(\<(/?[^\>]+)\>) doesn't work because it matches only html tags. I need a regex that matches all content that is not an HTML tag. In other words to negate the whole regex.

Here is a working example http://cafuego.net/2011/11/15/html-and-regular-expressions. But i suppose (?<=^|>)([^><]+?)(?=<|$) it works only in php.

1
asp.net-mvcregexregex-negationdata-annotations
What exactly do you want to allow and prevent? – Moby's Stunt Double
So what form exactly must be the form or the content of the textbox? Anything except HTML tags? That's sounds like something that should be just HTML-escaped. – Loamhoof
I want prevent html tags. text text - valid. text text <b> text </b> - invalid and user is warned he typed invalid signs – olly
Can't you just HTML-escape the input? I can't see any reason to forbid using html tags if they'll be escaped. – Loamhoof

1 Answers

0
votes

Based on one of your comments, you should be able to use a lookahead assertion to search for any tags; if one is found, then the assertion will fail, and the error message should be displayed.

e.g.

[RegularExpression(@"^(?![^<]*<[^>]+>).*$", ...