C# – failed to serialize the response in Web API

asp.net-web-apicserialization

I was working on ASP.NET MVC web API, I'm having this error:

The 'ObjectContent`1' type failed to serialize the response body for content type 'application/xml; charset=utf-8'.

My controller is:

public Employee GetEmployees()
{
    Employee employees = db.Employees.First();
    return employees;
}

why I m getting this error?

Best Answer

For me this was a problem with circular referencing.

The accepted answer did not work for me because it only changes the behaviour of the JSON formatter, but I was getting XML when I called the service from the browser.

To fix this, I switched off XML and forced only JSON to be returned.

In the Global.asax file, put the following lines at the top of your Application_Start method:

GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
GlobalConfiguration.Configuration.Formatters.Remove(GlobalConfiguration.Configuration.Formatters.XmlFormatter);

Now only JSON results will be returned. If you need XML results, you will need to find a different solution.

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

Json – How to get ASP.NET Web API to return JSON instead of XML using Chrome

Note: Read the comments of this answer, it can produce a XSS Vulnerability if you are using the default error handing of WebAPI

I just add the following in App_Start / WebApiConfig.cs class in my MVC Web API project.

config.Formatters.JsonFormatter.SupportedMediaTypes
    .Add(new MediaTypeHeaderValue("text/html") );

That makes sure you get JSON on most queries, but you can get XML when you send text/xml.

If you need to have the response Content-Type as application/json please check Todd's answer below.

NameSpace is using System.Net.Http.Headers.

Best Answer

Related Solutions

C# – the difference between String and string in C#

This is the style that Microsoft tends to use in their examples.

Json – How to get ASP.NET Web API to return JSON instead of XML using Chrome

Note: Read the comments of this answer, it can produce a XSS Vulnerability if you are using the default error handing of WebAPI

Related Topic