CODEWITHSUNDEEP
asp.net-mvcasp.net-mvc-3razor
bkaid
bkaid

Reputation: 52093

Replace line break characters with <br /> in ASP.NET MVC Razor view

I have a textarea control that accepts input. I am trying to later render that text to a view by simply using:

@Model.CommentText

This is properly encoding any values. However, I want to replace the line break characters with <br /> and I can't find a way to make sure that the new br tags don't get encoded. I have tried using HtmlString but haven't had any luck yet.

Upvotes: 283

Views: 192551

Answers (8)

xMilak
xMilak

Reputation: 1

simply put this inside your div where that text is and it will work.

<p>@Html.Raw(notam.Text.Replace("\r\n", "<br>").Replace("\n", "<br>"))</p>

Upvotes: 0

James S.
James S.

Reputation: 150

I prefer this method as it doesn't require manually emitting markup. I use this because I'm rendering Razor Pages to strings and sending them out via email, which is an environment where the white-space styling won't always work.

public static IHtmlContent RenderNewlines<TModel>(this IHtmlHelper<TModel> html, string content)
{
    if (string.IsNullOrEmpty(content) || html is null)
    {
        return null;
    }

    TagBuilder brTag = new TagBuilder("br");
    IHtmlContent br = brTag.RenderSelfClosingTag();
    HtmlContentBuilder htmlContent = new HtmlContentBuilder();

    // JAS: On the off chance a browser is using LF instead of CRLF we strip out CR before splitting on LF.
    string lfContent = content.Replace("\r", string.Empty, StringComparison.InvariantCulture);
    string[] lines = lfContent.Split('\n', StringSplitOptions.None);
    foreach(string line in lines)
    {
        _ = htmlContent.Append(line);
        _ = htmlContent.AppendHtml(br);
    }

    return htmlContent;
}

Upvotes: 0

Jacob Krall
Jacob Krall

Reputation: 28835

Use the CSS white-space property instead of opening yourself up to XSS vulnerabilities!

<span style="white-space: pre-line">@Model.CommentText</span>

Upvotes: 791

thelem
thelem

Reputation: 2782

Omar's third solution as an HTML Helper would be:

public static IHtmlString FormatNewLines(this HtmlHelper helper, string input)
{
    return helper.Raw(helper.Encode(input).Replace("\n", "<br />"));
}

Upvotes: 11

drzaus
drzaus

Reputation: 25034

Split on newlines (environment agnostic) and print regularly -- no need to worry about encoding or xss:

@if (!string.IsNullOrWhiteSpace(text)) 
{
    var lines = text.Split(new[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
    foreach (var line in lines)
    {
        <p>@line</p>
    }
}

(remove empty entries is optional)

Upvotes: 13

Andrea
Andrea

Reputation: 1868

I needed to break some text into paragraphs ("p" tags), so I created a simple helper using some of the recommendations in previous answers (thank you guys).

public static MvcHtmlString ToParagraphs(this HtmlHelper html, string value) 
    { 
        value = html.Encode(value).Replace("\r", String.Empty);
        var arr = value.Split('\n').Where(a => a.Trim() != string.Empty);
        var htmlStr = "<p>" + String.Join("</p><p>", arr) + "</p>";
        return MvcHtmlString.Create(htmlStr);
    }

Usage:

@Html.ToParagraphs(Model.Comments)

Upvotes: 4

Akaoni
Akaoni

Reputation: 1043

Applying the DRY principle to Omar's solution, here's an HTML Helper extension:

using System.Web.Mvc;
using System.Text.RegularExpressions;

namespace System.Web.Mvc.Html {
    public static class MyHtmlHelpers {
        public static MvcHtmlString EncodedReplace(this HtmlHelper helper, string input, string pattern, string replacement) {
            return new MvcHtmlString(Regex.Replace(helper.Encode(input), pattern, replacement));
        }
    }
}

Usage (with improved regex):

@Html.EncodedReplace(Model.CommentText, "[\n\r]+", "<br />")

This also has the added benefit of putting less onus on the Razor View developer to ensure security from XSS vulnerabilities.

My concern with Jacob's solution is that rendering the line breaks with CSS breaks the HTML semantics.

Upvotes: 5

Omar
Omar

Reputation: 40202

Try the following:

@MvcHtmlString.Create(Model.CommentText.Replace(Environment.NewLine, "<br />"))

Update:

According to marcind's comment on this related question, the ASP.NET MVC team is looking to implement something similar to the <%: and <%= for the Razor view engine.

Update 2:

We can turn any question about HTML encoding into a discussion on harmful user inputs, but enough of that already exists.

Anyway, take care of potential harmful user input.

@MvcHtmlString.Create(Html.Encode(Model.CommentText).Replace(Environment.NewLine, "<br />"))

Update 3 (Asp.Net MVC 3):

@Html.Raw(Html.Encode(Model.CommentText).Replace("\n", "<br />"))

Upvotes: 124

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