In normal asp.net MVC if I wanted to include custom html in the Validation summary that was placed there by the controller or other upstream processes and display it in Razor I would simply do something like:
@Html.Raw(HttpUtility.HtmlDecode(Html.ValidationSummary().ToHtmlString()))
in order to get the html decoded. This no longer seems to work in Asp.Net core. How can I achieve the same result in .net core 2.1?
In ASP.NET core, you can display a summary of the ModelState errors using asp-validation-summary (see validation documentation)
For example:
<div asp-validation-summary="ModelOnly" class="text-danger"></div>
If you need to access the errors directly and create your own custom html error summary/output, you can use @ViewData.ModelState
For example:
<ul>
@foreach (var error in ViewData.ModelState.SelectMany(x => x.Value.Errors))
{
<li>@error.ErrorMessage</li>
}
</ul>
If the error message contains raw html, you can use @Html.Raw()
For example:
<ul>
@foreach (var error in ViewData.ModelState.SelectMany(x => x.Value.Errors))
{
<li>@Html.Raw(error.ErrorMessage)</li>
}
</ul>
@Html.Raw(Html.ValidationSummary()) is because ValidationSummary() returns html encoded output. You could possibly try to WriteTo using a custom encoder (that you would have to write, see stackoverflow.com/a/33679999/3878764), but I think my solution is easier and more maintainable. You could even make a partial view of my solution.