ASP NET Core return JSON with status code

Question

I m looking for the correct way to return JSON with a HTTP status code in my  NET Core Web API controller  I use to use it like this   public IHttpActionResult GetResourceData         return this Content HttpStatusCode OK  new   response    Hello         This was in a 4 6 MVC application but now with  NET Core I don t seem to have this IHttpActionResult I have ActionResult and using like this   public ActionResult IsAuthenticated         return Ok Json  123         But the response from the server is weird  as in the image below     I just want the Web API controller to return JSON with a HTTP status code like I did in Web API 2

User · Answer

You have predefined methods for most common status codes.

Ok(result) returns 200 with response
CreatedAtRoute returns 201 + new resource URL
NotFound returns 404
BadRequest returns 400 etc.

See BaseController.cs and Controller.cs for a list of all methods.

But if you really insist you can use StatusCode to set a custom code, but you really shouldn't as it makes code less readable and you'll have to repeat code to set headers (like for CreatedAtRoute).

public ActionResult IsAuthenticated()
{
    return StatusCode(200, "123");
}

User · Answer

Please refer below code  You can manage multiple status code with different type JSON   public async Task lt HttpResponseMessage gt  GetAsync         try               using  var entities   new DbEntities                          var resourceModelList   entities Resources Select r  gt  new ResourceModel Build Your Resource Model   ToList                 if  resourceModelList Count    0                                return this Request CreateResponse lt string gt  HttpStatusCode NotFound   No resources found                                return this Request CreateResponse lt List lt ResourceModel gt  gt  HttpStatusCode OK  resourceModelList   application json                        catch  Exception ex                return this Request CreateResponse lt string gt  HttpStatusCode InternalServerError   Something went wrong

User · Answer

The most basic version responding with a JsonResult is      GET  api authors  HttpGet  public JsonResult Get         return Json  authorRepository List         However  this isn t going to help with your issue because you can t explicitly deal with your own response code      The way to get control over the status results  is you need to return a ActionResult which is where you can then take advantage of the StatusCodeResult type    for example      GET  api authors search namelike foo  HttpGet  Search    public IActionResult Search string namelike        var result    authorRepository GetByNameSubstring namelike       if   result Any                  return NotFound namelike             return Ok result       Note both of these above examples came from a great guide available from Microsoft Documentation  Formatting Response Data    Extra Stuff  The issue I come across quite often is that I wanted more granular control over my WebAPI rather than just go with the defaults configuration from the  New Project  template in VS   Let s make sure you have some of the basics down     Step 1  Configure your Service  In order to get your ASP NET Core WebAPI to respond with a JSON Serialized Object along full control of the status code  you should start off by making sure that you have included the AddMvc   service in your ConfigureServices method usually found in Startup cs      It s important to note thatAddMvc   will automatically include the Input Output Formatter for JSON along with responding to other request types    If your project requires full control and you want to strictly define your services  such as how your WebAPI will behave to various request types including application json and not respond to other request types  such as a standard browser request   you can define it manually with the following code   public void ConfigureServices IServiceCollection services           Build a customized MVC implementation  without using the default AddMvc    instead use AddMvcCore           https   github com aspnet Mvc blob dev src Microsoft AspNetCore Mvc MvcServiceCollectionExtensions cs      services          AddMvcCore options   gt                        options RequireHttpsPermanent   true     does not affect api requests             options RespectBrowserAcceptHeader   true     false by default               options OutputFormatters RemoveType lt HttpNoContentOutputFormatter gt                    remove these two below  but added so you know where to place them                options OutputFormatters Add new YourCustomOutputFormatter                  options InputFormatters Add new YourCustomInputFormatter                           AddApiExplorer              AddAuthorization            AddFormatterMappings              AddCacheTagHelper              AddDataAnnotations              AddCors            AddJsonFormatters       JSON  or you can build your own custom one  above      You will notice that I have also included a way for you to add your own custom Input Output formatters  in the event you may want to respond to another serialization format  protobuf  thrift  etc    The chunk of code above is mostly a duplicate of the AddMvc   method  However  we are implementing each  default  service on our own by defining each and every service instead of going with the pre-shipped one with the template  I have added the repository link in the code block  or you can check out AddMvc   from the GitHub repository    Note that there are some guides that will try to solve this by  undoing  the defaults  rather than just not implementing it in the first place    If you factor in that we re now working with Open Source  this is redundant work  bad code and frankly an old habit that will disappear soon     Step 2  Create a Controller  I m going to show you a really straight-forward one just to get your question sorted   public class FooController        HttpPost      public async Task lt IActionResult gt  Create  FromBody  Object item                if  item    null  return BadRequest             var newItem   new Object       create the object to return         if  newItem    null  return Ok newItem            else return NotFound                Step 3  Check your Content-Type and Accept  You need to make sure that your Content-Type and Accept headers in your request are set properly  In your case  JSON   you will want to set it up to be application json   If you want your WebAPI to respond as JSON as default  regardless of what the request header is specifying you can do that in a couple ways   Way 1 As shown in the article I recommended earlier  Formatting Response Data  you could force a particular format at the Controller Action level  I personally don t like this approach    but here it is for completeness      Forcing a Particular Format If you would like to restrict the response formats for a specific action you can  you can apply the    Produces  filter  The  Produces  filter specifies the response   formats for a specific action  or controller   Like most Filters  this   can be applied at the action  controller  or global scope    Produces  application json    public class AuthorsController       The  Produces  filter will force all actions within the   AuthorsController to return JSON-formatted responses  even if other   formatters were configured for the application and the client provided   an Accept header requesting a different  available format    Way 2 My preferred method is for the WebAPI to respond to all requests with the format requested  However  in the event that it doesn t accept the requested format  then fall-back to a default  ie  JSON   First  you ll need to register that in your options  we need to rework the default behavior  as noted earlier   options RespectBrowserAcceptHeader   true     false by default   Finally  by simply re-ordering the list of the formatters that were defined in the services builder  the web host will default to the formatter you position at the top of the list  ie position 0    More information can be found in this  NET Web Development and Tools Blog entry

User · Answer

I got this to work   My big issue was my json was a string  in my database   and not a specific known Type    Ok  I finally got this to work        Route  api  controller          ApiController      public class MyController  Microsoft AspNetCore Mvc ControllerBase                                public IActionResult MyMethod string myParam                         string hardCodedJson                             int hardCodedStatusCode   200                       Newtonsoft Json Linq JObject job   Newtonsoft Json Linq JObject Parse hardCodedJson                           this  comes from your class being a subclass of Microsoft AspNetCore Mvc ControllerBase                        Microsoft AspNetCore Mvc ContentResult contRes   this Content job ToString                         contRes StatusCode   hardCodedStatusCode                       return contRes                                  end MyMethod                          end class   I happen to be on asp net core 3 1   region Assembly Microsoft AspNetCore Mvc Core  Version 3 1 0 0  Culture neutral  PublicKeyToken adb9793829ddae60   C  Program Files dotnet packs Microsoft AspNetCore App Ref 3 1 0 ref netcoreapp3 1 Microsoft AspNetCore Mvc Core dll   I got the hint from here       https   www jianshu com p 7b3e92c42b61

User · Answer

Controller action return types in ASP NET Core web API 02 03 2020 6 minutes to read  2 By Scott Addie Link Synchronous action  HttpGet  quot  id  quot     ProducesResponseType StatusCodes Status200OK    ProducesResponseType StatusCodes Status404NotFound   public ActionResult lt Product gt  GetById int id        if    repository TryGetProduct id  out var product                 return NotFound               return product     Asynchronous action  HttpPost   Consumes MediaTypeNames Application Json    ProducesResponseType StatusCodes Status201Created    ProducesResponseType StatusCodes Status400BadRequest   public async Task lt ActionResult lt Product gt  gt  CreateAsync Product product        if  product Description Contains  quot XYZ Widget quot                  return BadRequest               await  repository AddProductAsync product        return CreatedAtAction nameof GetById   new   id   product Id    product

User · Answer

The easiest way I came up with is    var result   new Item   Id   123  Name    Hero      return new JsonResult result        StatusCode   StatusCodes Status201Created    Status code here

User · Answer

Awesome answers I found here and I also tried this return statement see StatusCode whatever code you wish  and it worked     return Ok new                       Token   new JwtSecurityTokenHandler   WriteToken token                       Expiration   token ValidTo                      username   user FullName                      StatusCode   StatusCode 200

User · Answer

The cleanest solution I have found is to set the following in my ConfigureServices method in Startup cs  In my case I want the TZ info stripped  I always want to see the date time as the user saw it      services AddControllers                    AddNewtonsoftJson o   gt                                        o SerializerSettings DateTimeZoneHandling   DateTimeZoneHandling Unspecified                       The DateTimeZoneHandling options are Utc  Unspecified  Local or RoundtripKind I would still like to find a way to be able to request this on a per-call bases  something like   static readonly JsonMediaTypeFormatter  jsonFormatter   new JsonMediaTypeFormatter      jsonFormatter SerializerSettings   new JsonSerializerSettings                    DateTimeZoneHandling   DateTimeZoneHandling Unspecified    return Ok  quot Hello World quot    jsonFormatter     I am converting from ASP NET and there I used the following helper method public static ActionResult lt T gt  Ok lt T gt  T result  HttpContext context                var responseMessage   context GetHttpRequestMessage   CreateResponse HttpStatusCode OK  result   jsonFormatter           return new ResponseMessageResult responseMessage

User · Answer

Instead of using 404 201 status codes using enum        public async Task lt IActionResult gt  Login string email  string password                if  string IsNullOrWhiteSpace email     string IsNullOrWhiteSpace password                          return StatusCode  int HttpStatusCode BadRequest  Json  email or password is null                         var user   await  userManager FindByEmailAsync email           if  user    null                        return StatusCode  int HttpStatusCode BadRequest  Json  Invalid Login and or password                        var passwordSignInResult   await  signInManager PasswordSignInAsync user  password  isPersistent  true  lockoutOnFailure  false           if   passwordSignInResult Succeeded                        return StatusCode  int HttpStatusCode BadRequest  Json  Invalid Login and or password                       return StatusCode  int HttpStatusCode OK  Json  Sucess

User · Answer

What I do in my Asp Net Core Api applications it is to create a class that extends from ObjectResult and provide many constructors to customize the content and the status code  Then all my Controller actions use one of the costructors as appropiate  You can take a look at my implementation at  https   github com melardev AspNetCoreApiPaginatedCrud  and  https   github com melardev ApiAspCoreEcommerce  here is how the class looks like go to my repo for full code    public class StatusCodeAndDtoWrapper   ObjectResult          public StatusCodeAndDtoWrapper AppResponse dto  int statusCode   200    base dto                StatusCode   statusCode             private StatusCodeAndDtoWrapper AppResponse dto  int statusCode  string message    base dto                StatusCode   statusCode          if  dto FullMessages    null              dto FullMessages   new List lt string gt  1           dto FullMessages Add message              private StatusCodeAndDtoWrapper AppResponse dto  int statusCode  ICollection lt string gt  messages    base dto                StatusCode   statusCode          dto FullMessages   messages            Notice the base dto  you replace dto by your object and you should be good to go

User · Answer

This is my easiest solution   public IActionResult InfoTag         return Ok new  name    Fabio   age   42  gender    M         or  public IActionResult InfoTag         return Json new  name    Fabio   age   42  gender    M

User · Answer

With ASP NET Core 2 0  the ideal way to return object from Web API  which is unified with MVC and uses same base class Controller  is  public IActionResult Get         return new OkObjectResult new Item   Id   123  Name    Hero          Notice that   It returns with 200 OK status code  it s an Ok type of ObjectResult  It does content negotiation  i e  it ll return based on Accept header in request  If Accept  application xml is sent in request  it ll return as XML  If nothing is sent  JSON is default    If it needs to send with specific status code  use ObjectResult or StatusCode instead  Both does the same thing  and supports content negotiation    return new ObjectResult new Item   Id   123  Name    Hero       StatusCode   200    return StatusCode  200  new Item   Id   123  Name    Hero        or even more fine grained with ObjectResult    Microsoft AspNetCore Mvc Formatters MediaTypeCollection myContentTypes   new Microsoft AspNetCore Mvc Formatters MediaTypeCollection   System Net Mime MediaTypeNames Application Json     String hardCodedJson       Id     123     DateOfRegistration     2012-10-21T00 00 00 05 30     Status   0     return new ObjectResult hardCodedJson    StatusCode   200  ContentTypes   myContentTypes      If you specifically want to return as JSON  there are couple of ways    GET http   example com api test asjson  HttpGet  AsJson    public JsonResult GetAsJson         return Json new Item   Id   123  Name    Hero           GET http   example com api test withproduces  HttpGet  WithProduces     Produces  application json    public Item GetWithProduces         return new Item   Id   123  Name    Hero         Notice that   Both enforces JSON in two different ways  Both ignores content negotiation  First method enforces JSON with specific serializer Json object   Second method does the same by using Produces   attribute  which is a ResultFilter  with contentType   application json   Read more about them in the official docs  Learn about filters here   The simple model class that is used in the samples  public class Item       public int Id   get  set        public string Name   get  set

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