ASP.NET Web API - Model Binding not working with XML data on POST

Question

I have not been able to get model binding to work when doing a POST using XML data with ASP.NET Web API. JSON data works fine.

Using a brand new Web API project, here are my model classes:

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class PostResponse
{
    public string ResponseText { get; set; }
}

Here is my post method in the controller:

    public PostResponse Post([FromBody]Person aPerson)
    {
        var responseObj = new PostResponse();
        if (aPerson == null)
        {
            responseObj.ResponseText = "aPerson is null";
            return responseObj;
        }

        if (aPerson.FirstName == null)
        {
            responseObj.ResponseText = "First Name is null";
            return responseObj;
        }

        responseObj.ResponseText = string.Format("The first name is {0}", aPerson.FirstName);
        return responseObj;
    }

I am able to run it successfully with JSON from Fiddler:

Request Headers:
User-Agent: Fiddler
Host: localhost:49188
Content-Type: application/json; charset=utf-8
Content-Length: 38

Request Body:
{"FirstName":"Tom","LastName":"Jones"}

Result:
{"ResponseText":"The first name is Tom"}

When passing in XML, the Person object is not hydrated correctly:

Request Headers:
User-Agent: Fiddler
Host: localhost:49188
Content-Type: text/xml
Content-Length: 79

Request Body:
<Person>
    <FirstName>Tom</FirstName>
    <LastName>Jones</LastName>
</Person>

Result:
<ResponseText>aPerson is null</ResponseText>

From what I understand XML should work similar to JSON. Any suggestions on what I’m missing here?

Thanks,
Skip

Answer 1

Add this in your WebApiConfig.cs:

config.Formatters.XmlFormatter.UseXmlSerializer = true;

This forced Web API to use XMLSerializer instead of DataContractSerializer and allows you to pass raw XML.

Otherwise you have to pass fully qualify datacontract XML i.e.:

<Person xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/Test.WebAPI.Controllers">
<FirstName>a</FirstName>
<LastName>b</LastName>
</Person>