如何强制ASP.NET Web API始终返回JSON?

How to force ASP.NET Web API to always return JSON?

ASP.NET Web API默认情况下执行内容协商-将返回基于Accept头的XML、JSON或其他类型。我不需要/不想要这个,有没有一种方法(比如属性或其他东西)告诉Web API总是返回JSON?


清除所有格式化程序,然后重新添加JSON格式化程序。

1
2
GlobalConfiguration.Configuration.Formatters.Clear();
GlobalConfiguration.Configuration.Formatters.Add(new JsonMediaTypeFormatter());

编辑

我把它加到了Global.asaxApplication_Start()里面。


仅支持ASP.NET Web API中的JSON–正确的方法

用jsonContentNegotiator替换IContentNegotiator:

1
2
3
var jsonFormatter = new JsonMediaTypeFormatter();
//optional: set serializer settings here
config.Services.Replace(typeof(IContentNegotiator), new JsonContentNegotiator(jsonFormatter));

JSonContentNegotiator实现:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
public class JsonContentNegotiator : IContentNegotiator
{
    private readonly JsonMediaTypeFormatter _jsonFormatter;

    public JsonContentNegotiator(JsonMediaTypeFormatter formatter)
    {
        _jsonFormatter = formatter;    
    }

    public ContentNegotiationResult Negotiate(
            Type type,
            HttpRequestMessage request,
            IEnumerable<MediaTypeFormatter> formatters)
    {
        return new ContentNegotiationResult(
            _jsonFormatter,
            new MediaTypeHeaderValue("application/json"));
    }
}


Philip W给出了正确的答案,但为了清晰和完整的工作解决方案,请编辑global.asax.cs文件,如下所示:(注意,我必须将引用system.net.http.formatting添加到stock生成的文件中)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http.Formatting;
using System.Web;
using System.Web.Http;
using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;

namespace BoomInteractive.TrainerCentral.Server {
    // Note: For instructions on enabling IIS6 or IIS7 classic mode,
    // visit http://go.microsoft.com/?LinkId=9394801

    public class WebApiApplication : System.Web.HttpApplication {
        protected void Application_Start() {
            AreaRegistration.RegisterAllAreas();

            WebApiConfig.Register(GlobalConfiguration.Configuration);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            //Force JSON responses on all requests
            GlobalConfiguration.Configuration.Formatters.Clear();
            GlobalConfiguration.Configuration.Formatters.Add(new JsonMediaTypeFormatter());
        }
    }
}

1
GlobalConfiguration.Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();

这将清除XML格式化程序,因此默认为JSON格式。


受Dmitry Pavlov出色答案的启发,我稍微修改了它,以便可以插入我想要执行的任何格式化程序。

归功于德米特里。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
/// <summary>
/// A ContentNegotiator implementation that does not negotiate. Inspired by the film Taken.
/// </summary>
internal sealed class LiamNeesonContentNegotiator : IContentNegotiator
{
    private readonly MediaTypeFormatter _formatter;
    private readonly string _mimeTypeId;

    public LiamNeesonContentNegotiator(MediaTypeFormatter formatter, string mimeTypeId)
    {
        if (formatter == null)
            throw new ArgumentNullException("formatter");

        if (String.IsNullOrWhiteSpace(mimeTypeId))
            throw new ArgumentException("Mime type identifier string is null or whitespace.");

        _formatter = formatter;
        _mimeTypeId = mimeTypeId.Trim();
    }

    public ContentNegotiationResult Negotiate(Type type, HttpRequestMessage request, IEnumerable<MediaTypeFormatter> formatters)
    {
        return new ContentNegotiationResult(_formatter, new MediaTypeHeaderValue(_mimeTypeId));
    }
}

如果您只想对一个方法执行此操作,那么将您的方法声明为返回HttpResponseMessage,而不是返回IEnumerable,并执行以下操作:

1
2
3
4
    public HttpResponseMessage GetAllWhatever()
    {
        return Request.CreateResponse(HttpStatusCode.OK, new List<Whatever>(), Configuration.Formatters.JsonFormatter);
    }

此代码对于单元测试来说很麻烦,但也可能是这样:

1
2
3
    sut = new WhateverController() { Configuration = new HttpConfiguration() };
    sut.Configuration.Formatters.Add(new Mock<JsonMediaTypeFormatter>().Object);
    sut.Request = new HttpRequestMessage();


这设置了正确的标题。看起来有点优雅。

1
2
3
4
public JsonResult<string> TestMethod()
{
return Json("your string or object");
}


对于那些使用OWIN的人

1
2
GlobalConfiguration.Configuration.Formatters.Clear();
GlobalConfiguration.Configuration.Formatters.Add(new JsonMediaTypeFormatter());

变为(在startup.cs中):

1
2
3
4
5
6
7
8
9
10
   public void Configuration(IAppBuilder app)
        {
            OwinConfiguration = new HttpConfiguration();
            ConfigureOAuth(app);

            OwinConfiguration.Formatters.Clear();
            OwinConfiguration.Formatters.Add(new DynamicJsonMediaTypeFormatter());

            [...]
        }

您可以在webapiconfig.cs中使用:

1
config.Formatters.JsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));