.NET core web API, how to change the root name of the XML returned when using IAsyncEnumerable?

Question

I would like to use the new IAsyncEnumerable<T> in my .net core 3.1 web api. This works alright, except I am not happy with the name of the XML root element. It appears to be ArrayOfX and I would like something like Xs. How do I achieve this?

To be more specific. My controller:

[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
    private static readonly string[] Summaries = new[]
    {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };

    [HttpGet]
    public async IAsyncEnumerable<WeatherForecast> Get()
    {
        await Task.Delay(0);
        var rng = new Random();

        for (var index = 1; index < 5; index++)
        {
            yield return new WeatherForecast
            {
                Date = DateTime.Now.AddDays(index),
                TemperatureC = rng.Next(-20, 55),
                Summary = Summaries[rng.Next(Summaries.Length)]
            };
        }
    }
}

public class WeatherForecast
{
    public DateTime Date { get; set; }
    public int TemperatureC { get; set; }
    public string Summary { get; set; }
}

In Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers();
    services.AddMvcCore(options =>
        {
            options.OutputFormatters.Clear(); // Remove json for simplicity
            options.OutputFormatters.Add(new XmlSerializerOutputFormatter());
        });
}

And the XML output:

<ArrayOfWeatherForecast xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><WeatherForecast><Date>2020-03-26T08:39:59.2303161+01:00</Date><TemperatureC>-13</TemperatureC><Summary>Warm</Summary></WeatherForecast><WeatherForecast><Date>2020-03-27T08:39:59.2389359+01:00</Date><TemperatureC>22</TemperatureC><Summary>Sweltering</Summary></WeatherForecast><WeatherForecast><Date>2020-03-28T08:39:59.2389696+01:00</Date><TemperatureC>33</TemperatureC><Summary>Scorching</Summary></WeatherForecast><WeatherForecast><Date>2020-03-29T08:39:59.2389719+02:00</Date><TemperatureC>-2</TemperatureC><Summary>Bracing</Summary></WeatherForecast></ArrayOfWeatherForecast>

How do I get WeatherForecasts instead of ArrayOfWeatherForecast?

Looks like the issue is probably in ControllerBase. With Xml serialization you current have public WeatherForecast[] WeatherForeCast { get;set;} To fix you need to add before the previous line [XmlElement("WeatherVoreCast")]. I believe that is burried in the ControllerBase code. — jdweng
– jdweng, Commented Mar 25, 2020 at 9:12
@jdweng My demo project is based on a Microsoft template with a few modifications, all of these listed above. There is no property of type WeatherForecast[], only the Get() method in the controller. And ControllerBase is part of standard mvc (namespace Microsoft.AspNetCore.Mvc). So I am not sure what you mean. — Jesper Mygind
– Jesper Mygind, Commented Mar 25, 2020 at 9:25
That is what I thought. The service is automatically when it see the array creating two xml tags (ArrayOfWeatherForecast,and WeatherForecast). The service is using Xml Serialization to read/write XML. Xml doesn't allow an array as the root element. If you have only one WeatherForeCast the remove the Enumerable from IAsyncEnumerable<WeatherForecast>. — jdweng
– jdweng, Commented Mar 25, 2020 at 10:32
@jdweng I would like to use the IAsyncEnumerable (see learn.microsoft.com/en-us/aspnet/core/web-api/… for further details) to return multiple items. But thanks for your suggestion. — Jesper Mygind
– Jesper Mygind, Commented Mar 25, 2020 at 10:59
You can't have your cake and have pie too. If you want IAsyncEnumerable as root element in xml then you are going to live with ArrayOfWeatherForecast. Since your can't have an array as root in xml with serialization. — jdweng
– jdweng, Commented Mar 25, 2020 at 11:28

Ryan · Accepted Answer · 2020-03-26 06:53:14Z

3

You could write your own XmlSerializerOutputFormatter like below:

public class MyCustomXmlSerializerOutputFormatter : XmlSerializerOutputFormatter
{
    protected override void Serialize(XmlSerializer xmlSerializer, XmlWriter xmlWriter, object value)
    {

        xmlSerializer = new XmlSerializer(typeof(List<WeatherForecast>) ,new XmlRootAttribute("WeatherForecasts"));

        xmlSerializer.Serialize(xmlWriter, value);
    }
}

Startup.cs

public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers();
        services.AddMvcCore(options =>
        {
            options.OutputFormatters.Clear(); // Remove json for simplicity
            options.OutputFormatters.Add(new MyCustomXmlSerializerOutputFormatter());
        });
    }

Result:

answered Mar 26, 2020 at 6:53

Ryan

20.3k10 gold badges44 silver badges68 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Jesper Mygind Over a year ago

Absolutely perfect. Thanks

Collectives™ on Stack Overflow

.NET core web API, how to change the root name of the XML returned when using IAsyncEnumerable?

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related