Returning generated HTML from .NET Core controller

Question

I have a .NET Core 2 app that needs to be able to return generated HTML from a controller. I've been able to get it returning the HTML as plain text, but not to persuade the browser that it's HTML and render that; as soon as an HTML content type is provided, the content type negotiation appears to break it and it just renders a 406 Not Acceptable.

(Simplified) options I've tried -

    [HttpGet]
    [Produces("text/html")]
    public string Display()
    {
        return "<html><head><title>Testing</title><head><body>Hello, world!</body></html>";
    }

    [HttpGet]
    [Produces("text/html")]
    public HttpResponseMessage Display()
    {
        try
        {
            var response = new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent("<html><head><title>Testing</title><head><body>Hello, world!</body></html>")
            };
            response.Content.Headers.ContentType = new MediaTypeHeaderValue("text/html");

            return response;
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex.Message);
            return new HttpResponseMessage(HttpStatusCode.InternalServerError);
        }
    }

    [HttpGet]
    [Produces("text/html")]
    public IActionResult Display()
    {
        var pageHtml = "<html><head><title>Testing</title><head><body>Hello, world!</body></html>";
        var result = StatusCode(200, pageHtml);
        result.ContentTypes.Add(new MediaTypeHeaderValue("text/html"));

        return StatusCode(200, pageHtml);
    }

The Startup.ConfigureServices method has been tried with all combinations I can think of of the RespectBrowserAcceptHeader and ReturnHttpNotAcceptable properties, but they didn't seem to make a difference.

Can anyone see what I've missed to persuade the server to just return the generated HTML?

You cannot use an explanation mark. It is a special character. See : en.wikipedia.org/wiki/… — jdweng
– jdweng, Commented May 13, 2019 at 23:34

brandonhein · Accepted Answer · 2019-05-14 02:12:22Z

3

How/why are you generating html yourself? I think an eaiser solution might be to make an ASP.NET Core 2 MVC app. That will allow you to use ViewModels. I'd take a look into that.

Anyways, try returning Content... this returns a Http Status code of 200, and will allow you to return a string with other details of how the content is formatted.

[HttpGet]
[Produces("text/html")]
public IActionResult Display()
{
     return Content("<html><h1>hello world!</h1></html>", "text/html", Encoding.UTF8);
}

answered May 14, 2019 at 2:12

brandonhein

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1 Comment

eftpotrm Over a year ago

It's an unusual requirement, I agree, but definitely better than a more standard approach (which has already been tried) in this case. Thanks - that works :-)

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