Issue using .Net Core 2.2 LinkGenerator - c#

In my controller.Post I am using a link generator to return the endpoint of the newly added resource to the user. The link generator always returns null and I cant quite put my finger on why?
I included controller code that is adding to the database. Note the line calling _linkGenerator.GetPathByAction - the parameters passed in are (in order) 1. the action (in this case the name of the method that does the 'Get'), 2, the controller name and 3 an anonymous type containing the correct Id. I honestly cant see a problem with this.
how the controller name is defined :
namespace CarPriceComparison.Controllers.Api{
[Route("api/vehicles")]
[ApiController]
public class VehicleController : Controller
'Get' Action - function header :-
[HttpGet("{vehicleId_:int}")]
public IActionResult GetVehicle(int vehicleId_)
{
'problem' code that does the get. To me, the parameters passed into _linkGenerator.GetPathByAction look perfectly fine. Suggestions as to why I am always returned a null value?
[HttpPost("")]
public async Task<IActionResult> PostNewVehicleData(VehicleViewModel vehicleData_)
{
try
{
if (ModelState.IsValid)
{
var newVehicle = _mapper.Map<Vehicle>(vehicleData_);
_vehicleRepository.AddVehicle(newVehicle);
var location = _linkGenerator.GetPathByAction("GetVehicle", "vehicles",
new {vehicleId_ = newVehicle.Id});
if (string.IsNullOrWhiteSpace(location))
{
return BadRequest("could not use vehicleId_ to create a new vehicle in the dataase");
}
if (await _vehicleRepository.SaveChangesAsync())
{
var vehicleModel = _mapper.Map<VehicleViewModel>(newVehicle);
return Created(location, _mapper.Map<VehicleViewModel>(newVehicle));
}
}
return BadRequest("Failed to save the vehicle");
}
catch(Exception ex)
{
return BadRequest($"Exception Thrown : {ex}");
}
}

You have to try this:
var location = _linkGenerator.GetPathByAction("GetVehicle", "Vehicle",
new {vehicleId_ = newVehicle.Id});
Or remane your controller to VehiclesController. Then try this:
var location = _linkGenerator.GetPathByAction("GetVehicle", "Vehicles",
new {vehicleId_ = newVehicle.Id});

Related

Unable to return anonymous object through an IActionResult Endpoint

I have a problem when I try to return an anonymous object/DTO from an endpoint in my ASP .NET Core 6 Web-Api Project. I get an error that it cannot implicitly convert the type to an IActionResult. The code I use was suggested in this answer but unfortunately it doesn't work out for me, I also tried using to map the anonymous object to an dto but that didn't work either. Any help would be greatly appreciated, thanks in advance.
I also tried to return an Json(output) like suggested in the answer but, Json() I can't specify a using for "Json", I also tried to return an JsonResult(output) by modifying the return type of the endpoint but that didn't work either.
This is the code I use:
[HttpGet]
public IActionResult GetAllEndpoints()
{
var endpoints = _endpoinDataSources
.SelectMany(es => es.Endpoints)
.OfType<RouteEndpoint>();
var output = endpoints.Select(
e =>
{
var controller = e.Metadata
.OfType<ControllerActionDescriptor>()
.FirstOrDefault();
var action = controller != null
? $"{controller.ControllerName}.{controller.ActionName}"
: null;
var controllerMethod = controller != null
? $"{controller.ControllerTypeInfo.FullName}:{controller.MethodInfo.Name}"
: null;
return new GetEndpointsDto
{
Method = e.Metadata.OfType<HttpMethodMetadata>().FirstOrDefault()?.HttpMethods?[0],
Route = $"/{e.RoutePattern.RawText.TrimStart('/')}",
Action = action,
ControllerMethod = controllerMethod
};
}
);
return output;
}
I also injected the EndPointDataSource through the controller constructor:
public MyController(IEnumerable<EndpointDataSource> endpointSources)
{
_endpoinDataSources = endpointSources;
}
You need to be more specific with return type:
[HttpGet]
public IActionResult<List<GetEndpointsDto>> GetAllEndpoints()
{
...
return Ok(output.toList())
}
You should try public ActionResult<object> GetAllEndpoints() and then return something like return Ok(output) or also just return output I realized that I'm returning output in a API of mine and it works fine

c# guid-field received null

I have following code:
public IActionResult Index()
{
_fileModel = new FileModel { Files = _fileService.GetFilesForArchivation(), IdOfService = default(Guid) };
return View(_fileModel);
}
and Iv'e implemented two methods also :
public IActionResult Compress()
{
//_compressingService.CompressAllFiles();
_fileModel.IdOfService = _compressResolverService.Start(_serviceProvider);
return RedirectToAction("Index");
}
public IActionResult CancelCompressing()
{
//_compressingService.Stop();
_compressResolverService.Stop(_fileModel.IdOfService);
return RedirectToAction("Index");
}
In first method Iv'e added IdOfService to FileModel. In second code I am trying to send this field as a parameter. In first method i get normal value of guid but in second method it has default value and i get
NullReferenceException
Kindly review this issue and give feedback.
If I understand correctly from one action to another you are losing your value, you can use
TempData["IdOfService"] = _fileModel.IdOfService;
TempData.Keep();
To keep this in "memory".

Return CreatedAtRoute location from ODataController

I have ODataController with a Post method in it which should return a URL to a newly created OData resource, something like the following:
public class TasksController: ODataController
{
[HttpPost]
public IActionResult Post([FromBody] Request request)
{
...
return CreatedAtRoute("GetTask", new Dictionary<string, object>{{"id", id}}, new object());
}
[ODataRoute(RouteName = "GetTask")]
public IActionResult Get(int key)
{
...
}
}
In my case I'm getting "InvalidOperationException: No route matches the supplied values" when returning CreatedAtRoute. I can fix the issue by changing code to:
return Created($"{baseUri}/odata/Task({id})", new object());
Is there any way to use CreatedAtRoute instead and making it return correct OData path?
I had this problem also. I was able to get it working by adding "odataPath" to the routeValues:
return CreatedAtAction(nameof(Get), new { id, odataPath = $"{baseUri}/odata/Task({id})" }, new object());
UPDATE:
I did find an alternate/better approach. When inheriting from ODataController, you have access to two additional result types: CreatedODataResult<TEntity> and UpdatedODataResult<TEntity>. So this works:
return Created(new object());
That returns a 201 with the OData-specific create route in the location header.
The route your are returning in the Created method: "{baseUri}/odata/Task({id})" doesn't exist. The simplest fix would be to change your URL to match your controller method.
Change: $"{baseUri}/odata/Task({id})"
to match $"{baseUri}/odata/GetTask({id})"

How to use a parameter in Web API v2?

I have no idea where to start with this. I asked a question previously, and someone suggested I look at attribute routing. I read up on it, and while it helped me to create the below code, I'm still not sure how to limit it like I want to.
public class ReviewController : ApiController
{
private Review db = new Review();
////This GET works. It was auto-generated by Visual Studio.
// GET: api/Review
public IQueryable<Review> GetReview()
{
return db.Review;
}
////This is the GET that I'm trying to write, but don't know what to do
// GET: api
[Route("api/review/site")]
[HttpGet]
public IEnumerable<Review> FindStoreBySite(int SiteID)
{
return db.Review
}
////This GET also works and was generated by VS.
// GET: api/Review/5
[ResponseType(typeof(Review))]
public IHttpActionResult GetReview(int id)
{
Review review = db.Review.Find(id);
if (review == null)
{
return NotFound();
}
return Ok(review);
}
Essentially what I'm aiming to do is to limit what's returned by the API to only the results where the SiteID is equal to whatever value is passed into the URL. I'm not even sure where to get started with this, and googling/searching stack overflow for "what to put in web api return" has been fruitless.
How do I tell the API what I want to have returned based off a parameter besides ReviewID?
Edit: I've updated the code per the suggestions in the answer below, but now I'm getting a new error.
Here's the current code:
private ReviewAPIModel db = new ReviewAPIModel();
// GET: api/Review
[Route("api/Review")]
[HttpGet]
public IQueryable<Review> GetReview()
{
return db.Review;
}
// GET: api
[Route("api/Review/site/{siteid}")]
[HttpGet]
public IEnumerable<Review> FindStoreBySite(int siteid)
{
return db.Review.Where(Review => Review.SiteID == siteid);
}
// GET: api/Review/5
[ResponseType(typeof(Review))]
public IHttpActionResult GetReview(int id)
{
Review review = db.Review.Find(id);
if (review == null)
{
return NotFound();
}
return Ok(review);
}
}
Here's the error that I get:
Multiple actions were found that match the request
When I google it, it takes me to this question: Multiple actions were found that match the request in Web Api
However, I've tried the answers there (I've confirmed that I'm using Web API V2, and my webapiconfig.cs file includes the config.MapHttpAttributeRoutes(); line.
In addition, as you can see in my code above, I've included the appropriate routing. However, I'm still getting an error telling me that it's returning two conflicting API calls.
To pass parameters to a WebApi controller you need to add a [Route()] attribute to that controller and mark the part of the link that's used as the attribute with this {}.
To return reviews that only match the passed in parameter you need to use LINQ to filter the data.
Here is an example:
[Route("api/getFoo/{id}")]
public IHttpActionResult GetFoo(int id)
{
return db.Foo.Where(x => x.Id == id);
}
The {id} part of the string represents the id that will be in the url in your browser: http://localhost:51361/api/getFoo/2. The "2" in the url IS the {id} property that you marked in your [Route("api/getFoo/{id}")] attribute.
I also modified your code:
public class ReviewController : ApiController
{
...
[Route("api/review/site/{siteId}")]
[HttpGet]
public IEnumerable<Review> FindStoreBySite(int SiteID)
{
return db.Review.Where(review => review.Id == SiteID);
}
...
Your request url should look somewhat like this: http://localhost:51361/api/review/site?SiteID=2
This can be difficult to wrap your head around at first but you'll get used to it eventually. It's how arguments are passed to Controller Action parameters.
if you want to get parameters for GET, it's like a simple overload, but if it's done, POST is with [fromBody], because the URL is in the tag [Route ("/abc/123/{id}")]
example
code
[Route ("/abc/123/{idSite}")]
[HttpGet]
public HttpResponseMessage ControllerIdSite(int IdSite){
//CODE . . .
return Request.CreateResponse<int>(HttpStatusCode.OK, IdSite);
}
call
/abc/123/17
return
17
OR
[Route ("/abc/123")]
[HttpGet]
public HttpResponseMessage ControllerIdSite(int IdSite){
//CODE . . .
return Request.CreateResponse<int>(HttpStatusCode.OK, IdSite);
}
call
/abc/123?IdSite=17
return
17

ASP.NET Core return JSON with status code

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.
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 =>
{
options.RequireHttpsPermanent = true; // does not affect api requests
options.RespectBrowserAcceptHeader = true; // false by default
//options.OutputFormatters.RemoveType<HttpNoContentOutputFormatter>();
//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<IActionResult> 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
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");
}
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; }
}
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
};
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"});
}
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)
});
Instead of using 404/201 status codes using enum
public async Task<IActionResult> 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 !!!"));
}
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("{id}")]
[ProducesResponseType(StatusCodes.Status200OK)]
[ProducesResponseType(StatusCodes.Status404NotFound)]
public ActionResult<Product> 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<ActionResult<Product>> CreateAsync(Product product)
{
if (product.Description.Contains("XYZ Widget"))
{
return BadRequest();
}
await _repository.AddProductAsync(product);
return CreatedAtAction(nameof(GetById), new { id = product.Id }, product);
}
Please refer below code, You can manage multiple status code with different type JSON
public async Task<HttpResponseMessage> GetAsync()
{
try
{
using (var entities = new DbEntities())
{
var resourceModelList = entities.Resources.Select(r=> new ResourceModel{Build Your Resource Model}).ToList();
if (resourceModelList.Count == 0)
{
return this.Request.CreateResponse<string>(HttpStatusCode.NotFound, "No resources found.");
}
return this.Request.CreateResponse<List<ResourceModel>>(HttpStatusCode.OK, resourceModelList, "application/json");
}
}
catch (Exception ex)
{
return this.Request.CreateResponse<string>(HttpStatusCode.InternalServerError, "Something went wrong.");
}
}
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<string>(1);
dto.FullMessages.Add(message);
}
private StatusCodeAndDtoWrapper(AppResponse dto, int statusCode, ICollection<string> 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.
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
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 =>
{
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("Hello World", _jsonFormatter );
I am converting from ASP.NET and there I used the following helper method
public static ActionResult<T> Ok<T>(T result, HttpContext context)
{
var responseMessage = context.GetHttpRequestMessage().CreateResponse(HttpStatusCode.OK, result, _jsonFormatter);
return new ResponseMessageResult(responseMessage);
}

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