How do I include a clickable hyperlink in ASP.NET MVC Core ModelState error message?

Question

In my controller, there are some custom validations. I want to provide a clickable hyperlink in the ModelState error message, that when clicked, will take the user to different page of the same site for further actions. Something like "Error: please click here to fix it". Here is the scaled down version of the controller.

public IActionResult LaunchItem()
{      
    var errorMsg = @"Error: Please click <a href=""https://localhost:44316/Controller/Action"" target=""_blank"">here</a> to fix error.";
    ModelState.AddModelError("", errorMsg);
    return View();
}

Here is the portion of the view that presents the error message.

<div asp-validation-summary="All" class="text-danger"></div>

I would like the message to show with the "here" being the clickable hyperlink:

Error: Please click <here> to fix error

Instead, the message include the whole anchor text, like this:

Error: Please click <a href="https://localhost:44316/Controller/Action" target="_blank">here</a> to fix error

I think this has something to do with encoding but I can't figure out how to make it work.

Answer 1

You could try as below:

In controller:

ModelState.AddModelError("", "Error");
 ViewBag.FixMessage = String.Format("Please click <a href={0}>Here</a> to fix", "/Home/Index").ToHtmlString();

In View:

//remove it
@*<div asp-validation-summary="ModelOnly" class="text-danger" ></div>*@

            @if (!ViewData.ModelState.IsValid&& ViewData.ModelState[""]?.Errors.Count>0)
            {
                <div class="text-danger validation-summary-errors">
                    @ViewBag.FixMessage;
                </div>
                
            }

Extension :

public static class MyExtension
    {
        public static HtmlString ToHtmlString(this String str)
        {
            return new HtmlString(str);
        }
    }

Result: