How to make ASP.NET Core return XML result?

Question

[HttpGet]
[HttpPost]
public HttpResponseMessage GetXml(string value)
{
    var xml = $"<result><value>{value}</value></result>";
    return new HttpResponseMessage
   {
       Content = new StringContent(xml, Encoding.UTF8, "application/xml")
   };
}

I called the action using Swagger and passed this parameter 'text value'

Expected result should be an XML file like this: text value

Actual Result: strange json result without the passed value! https://www.screencast.com/t/uzcEed7ojLe

I tried the following solutions but did not work:

services.AddMvc().AddXmlDataContractSerializerFormatters();
services.AddMvc().AddXmlSerializerFormatters();

Answer 1

Try this solution

[HttpGet]
[HttpPost]
public ContentResult GetXml(string value)
{
    var xml = $"<result><value>{value}</value></result>";
    return new ContentResult
    {
        Content = xml,
        ContentType = "application/xml",
        StatusCode = 200
    };
}

Answer 2

1. you are missing parameter in your attribute.
2. you can put produces attribute to declare what type of output format

3. you can embrace IActionResult or directly return ContentResult.

   [HttpGet("{value}")]
   [Produces("application/xml")]
   public IActionResult GetXml(string value)
   {
       var xml = $"<result><value>{value}</value></result>";
       //HttpResponseMessage response = new HttpResponseMessage();
       //response.Content = new StringContent(xml, Encoding.UTF8);
       //return response;
   
       return new ContentResult{
           ContentType = "application/xml",
           Content = xml,
           StatusCode = 200
       };
   }
   

The above will give you

<result>
    <value>hello</value>
</result>

you can refer to following link to understand more about IActionResult

What should be the return type of WEB API Action Method?