How to force ASP.NET Web API to return JSON or XML data based on my input?

Question

I try to get the output XML or JSON data based on my input. I used the below WEB API code but not able to exact output.

public string Get(int id)
{
    if (GlobalConfiguration.Configuration.Formatters.XmlFormatter == null)
    {
        GlobalConfiguration.Configuration.Formatters.Add(GlobalConfiguration.Configuration.Formatters.XmlFormatter);
    }
    if (GlobalConfiguration.Configuration.Formatters.JsonFormatter == null)
    {
        GlobalConfiguration.Configuration.Formatters.Add(GlobalConfiguration.Configuration.Formatters.JsonFormatter);
    }
    if (id == 1)
    {
        GlobalConfiguration.Configuration.Formatters.Remove(GlobalConfiguration.Configuration.Formatters.JsonFormatter);                
        GlobalConfiguration.Configuration.Formatters.XmlFormatter.UseXmlSerializer = true;                
    }
    else
    {
        GlobalConfiguration.Configuration.Formatters.Remove(GlobalConfiguration.Configuration.Formatters.XmlFormatter);
        GlobalConfiguration.Configuration.Formatters.JsonFormatter.UseDataContractJsonSerializer = true;
    }
    return "value";
}

Vivek Jain · Accepted Answer · 2014-03-10 14:04:43Z

82

Add the below code app_start event in global.asax file. In API Url add the query string:

GlobalConfiguration.Configuration.Formatters.JsonFormatter.MediaTypeMappings.Add(
    new QueryStringMapping("type", "json", new MediaTypeHeaderValue("application/json")));

GlobalConfiguration.Configuration.Formatters.XmlFormatter.MediaTypeMappings.Add(
    new QueryStringMapping("type", "xml", new MediaTypeHeaderValue("application/xml")));

e.g.:

for xml : http://localhost:49533/api/?type=xml

for json: http://localhost:49533/api/?type=json

edited Mar 10, 2014 at 14:04

Vivek Jain

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answered Nov 14, 2013 at 13:31

vijayjan15

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2 Comments

Khaled Musaied Over a year ago

here is a tip if you need to use Route instead of QueryString, I created a custom mapper by inheriting from "MediaTypeMapping" and overriding "TryMatchMediaType"

Lucas Over a year ago

Does it work with HTTP routing like [Route( "api/{type}/entity" )] ?

Badrinarayanan Lakshmiraghavan · Accepted Answer · 2013-11-14 12:32:27Z

10

What you are trying to do will not work in a multi-threaded environment. You cannot add to and remove from the formatters collection on a per-request basis. Here is a better way of accomplishing what you want.

public HttpResponseMessage Get(int id)
{
    Foo foo = new Foo();
    var content = new ObjectContent<Foo>(foo,
                    ((id == 1) ? Configuration.Formatters.XmlFormatter :
                                Configuration.Formatters.JsonFormatter));
    return new HttpResponseMessage()
    {
         Content = content
    };
}

answered Nov 14, 2013 at 12:32

Badrinarayanan Lakshmiraghavan

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1 Comment

jamiebarrow Over a year ago

Ah I see this is similar to the answer I found, nice

Community · Accepted Answer · 2017-05-23 12:03:08Z

8

Looked into this a bit more, and found your answer in another post:

public HttpResponseMessage Get(int id)
{
    string content = "value";

    if (id == 1)
    {
        return Request.CreateResponse<string>(HttpStatusCode.OK, content, Configuration.Formatters.JsonFormatter);
    }

    return Request.CreateResponse<string>(HttpStatusCode.OK, content, Configuration.Formatters.XmlFormatter);
}

edited May 23, 2017 at 12:03

CommunityBot

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answered Oct 23, 2014 at 8:30

jamiebarrow

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2 Comments

Kirkaiya Over a year ago

Now that actually does look useful!

jamiebarrow Over a year ago

@Kirkaiya I noticed Badri's answer afterwards, they're doing the same thing it seems, but this seems to make a lot more sense to me :) Thanks!

Eric Herlitz · Accepted Answer · 2015-09-29 19:52:08Z

6

It also works to force the accept headers. Great option if you aren't always returning HttpResponseMessage's. I.e

Request.Headers.Add("Accept", "text/json");
return Request.CreateResponse(HttpStatusCode.OK, yourobject);

or

Request.Headers.Add("Accept", "application/xml");
return new Rss20FeedFormatter(feed);

answered Sep 29, 2015 at 19:52

Eric Herlitz

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1 Comment

aemorales1 Over a year ago

Can the Request.Headers.Add piece be added at the controller level

Jim Yarbro · Accepted Answer · 2013-11-14 13:42:19Z

5

If your request specifies the mime type, for example application/json, then web api will format the response appropriately.

If you are attempting to debug your web api manually, use a tool like Fiddler 2 to specify the type.

This article describes the concept.

answered Nov 14, 2013 at 13:42

Jim Yarbro

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2 Comments

jamiebarrow Over a year ago

+1 I would suggest to do this as well, rather than a custom input on a query string, as it is the standard way to do it

jamiebarrow Over a year ago

Perhaps a better link is asp.net/web-api/overview/formats-and-model-binding/…

Paradox · Accepted Answer · 2014-05-15 10:51:27Z

4

QueryStringMapping` is nice solution but I need a default value for type.

for xml : localhost:49533/api/?type=xml

for json: localhost:49533/api/

I solve that situation like that:

GlobalConfiguration.Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();
var jSettings = new JsonSerializerSettings();

GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings = jSettings;
GlobalConfiguration.Configuration.Formatters.XmlFormatter.MediaTypeMappings.Add(new QueryStringMapping("xml", "true", new MediaTypeHeaderValue("application/xml")));

edited May 15, 2014 at 10:51

answered May 13, 2014 at 12:25

Paradox

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1 Comment

WorkSmarter Over a year ago

Add the code to the App_Start/WebApiConfig.cs file.

Community · Accepted Answer · 2017-05-23 10:31:32Z

3

While the accepted answer by vijayjan15 seems the best way to go for your specific situation (that is, using the MediaTypeMappings), you could alternatively have two different methods, one that returns XML and one that returns JSON. To do that, you can instantiate a controller-specific HttpConfiguration (to avoid modifying the one in GlobalConfiguration.Configuration):

public MyReturnType GetMyTypeAsXml() {
    Configuration = new HttpConfiguration();
    Configuration.Formatters.Clear();
    Configuration.Formatters.Add(new XmlMediaTypeFormatter());

    return new MyReturnType();
}

public MyReturnType GetMyTypeAsJson() {
    Configuration = new HttpConfiguration();
    Configuration.Formatters.Clear();
    Configuration.Formatters.Add(new JsonMediaTypeFormatter());

    return new MyReturnType();
}

I'm not sure how much overhead there is in spinning up a new instance of HttpConfiguration (I suspect not a lot), but the new instance comes with the Formatters collection filled by default, which is why you have to clear it right after instantiating it. Note that it if you don't use Configuration = new HttpConfiguration(), and instead modify Configuration directly, it modifies the GlobalConfiguration.Configuration property (so, it would impact all your other WebApi methods - bad!).

edited May 23, 2017 at 10:31

CommunityBot

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answered Jul 25, 2014 at 23:32

Kirkaiya

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2 Comments

Kirkaiya Over a year ago

My proposed alternate answer was based on the assumption that the question author either didn't have access to the request itself (eg, to modify the headers) or wanted to specify XML or JSON if the request originated in a browser (in which case, different browsers send different accept headers, so that FireFox will show XML, while IE will pull as JSON - if he wants to be explicit, he can't rely on the headers). ;-)

jamiebarrow Over a year ago

Yeah true, I was presuming he had control of the request with the check on id == 1 but I guess he was just trying it out in a sample project first, so good point :) I added an answer, think I found the best way of doing this in another SO post.

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