I have a restful WebAPI application that handles requests from an AngularJS app. The controller actions requiring the GET verb works fine, but actions with POST/PUT that does not return any content will throw a Nullreference Exception.
Example:
[HttpPut]
public void Update()
This gives me the following message after function execution returns:
System.NullReferenceException: Object reference not set to an instance of an object. <SendAsync>d__0.MoveNext
It will also return HTTP status code 204 to the client.
By changing method signature to be async and return an empty object it will work as expected:
[HttpPut]
[Route("")]
public async Task<object> Update(ProfileViewModel model)
{
_profileManager.Update(model);
return Ok(new {});
}
Note that just returning status code 200 will not work. Some content must also be returned, or else the exception is thrown.
This happens on every request that is not GET, including DELETE. How can I fix this without having to change the signature and return an anonymous object for every single method?
Please try this code without any _profileManager.Update(model);
Use IActionResult if you are using .net core.
return Ok() does not force you to return anything and should work.
if that does not work then check for any errors in your custom serializer.
if that WORKS then put back your _profileManager.Update(model) and check if that is throwing any errors.
[HttpPut]
[Route("")]
public async Task<IHttpActionResult> Update(ProfileViewModel model)
{
return Ok();
}
You don't have to return object:
[HttpPost]
public IActionResult Update()
{
return Ok();
}
Related
Web Api Controller Method
[Route("change-gross-profit")]
[HttpPost]
public IHttpActionResult UpdateGrossProfit(decimal grossProfit)
{
var customerGrossProfit = grossProfit / 100;
Context.UpdateCustomerCost();
return Ok();
}
Angular Http Call
public updateGrossProfit(grossProfit: number): Observable<void> {
const url = UrlTemplate.populate('api/customer/total', 'change-gross-profit', {});
return this._http.post<void>(url, grossProfit ,{withCredentials: true});
}
I am getting the 404 Method Not Found error.
I have also tried by passing data using JSON.stringify({'grossProfit' : grossProfit}) (Getting un-supported content-type error.)
Currently workaround is, I can create a class with required property and then pass that class instance as a body which I know that it will work. But I would like to avoid it as there is only one parameter that I want to pass into POST controller method so.
Any idea how can I pass the single parameter as an argument to Post controller method from Angular without creating a custom object?
You are passing the number just fine.
I tried the same with this code below and it works fine.
let no : number =5;
this.http.post<any>("https://xxxxx/postDecimal", no).subscribe(result => {
console.log(result);
});
This is my backend code:
[HttpPost("postDecimal")]
[ProducesResponseType(typeof(int), 200)]
[ProducesResponseType(typeof(string), 400)]
[ProducesResponseType(typeof(string), 403)]
public async Task<IActionResult> PostDecimal(decimal x)
{
return Ok(x);
}
Is your url fine? Since you got 404 Method not found error.
I have a HTTPPUT request that is not being called. I have a similar put request that manages another tab and it works. Both pages are pretty identical. I don't know what I am doing wrong.
I have tried almost everything and don't know what else to try.
controller:
[HttpPut]
[Route("updateAllocations({type})")]
public IHttpActionResult UpdateAllocations(string type, T_LOC entity)
{
System.Diagnostics.Debug.WriteLine("inside");
_allocationsService.UpdateAllocations(type,entity);
return Ok();
}
interface:
using OTPS.Core.Objects;
using System.Collections.Generic;
using OTPS.Core.Models;
namespace OTPS.Core.Interfaces
{
public interface IAllocationsService
{
void UpdateAllocations(string type, T_LOC entity);
}
}
service:
public void UpdateAllocations(string type, T_LOC entity)
{
System.Diagnostics.Debug.WriteLine("inside");
}
CLIENT SIDE:
public updateAllocation(type: string , entity) {
console.log("sdfsdf")
console.log(`${this.baseUrl}/api/allocations/updateAllocations(${type})`)
return this.http.put(`${this.baseUrl}/api/allocations/updateAllocations({type})`, entity, { headers: this.headers, withCredentials: true })
.pipe(catchError((error: Error) => {
console.log("sdfasd111111sdf")
return this.errorService.handleError(error);
}));
}
I am expecting the clinet side to call the put request before making any further logic but the print on server side never gets called..
Make sure that you subscribe to the service method inside component:
this.myService.updateAllocation(type, entity).subscribe( response => {
// do something here with response
});
You must call subscribe() or nothing happens. Just calling
Service method does not initiate the PUT/DELETE/POST/GET request.
Always subscribe!
An HttpClient method does not begin its HTTP request until you call
subscribe() on the observable returned by that method. This is true
for all HttpClient methods.
I was searching around but I couldn't find a working answer for my issue. I saw a similar question but we had different results. My issue is I have 2 controllers. The first controller has a POST action that I want to return a CreatedAtRoute to a GET action inside a different controller. I tested the GET action in Postman and it works so my only issue is getting the CreatedAtRoute to work.
My first controller:
[HttpPost]
public async Task<IActionResult> Submit(AssessmentAttemptVM attempt)
{
if (!ModelState.IsValid)
{
return BadRequest();
}
//Do database related stuff
await _context.SaveChangesAsync();
return CreatedAtRoute("GetAssessmentResult", new { id = studentAttempt.Id }, studentAttempt);
}
My second controller:
[HttpGet("{id}", Name = "GetAssessmentResult")]
public async Task<ActionResult<AssessmentResultVM>> GetById(int id)
{
//Get my ViewModel -- This works if I try to access it without using the CreatedAtRoute method
return resultVM;
}
The picture below shows what Postman responds with when I try to Post. I verified that the data gets added to the database so only the CreatedAtRoute method is the only I can think of that isn't making this work for me..
EDIT
Controller Route Attributes:
[ApiController]
[Route("api/view/assessmentresult/")]
public class AssessmentResultsController: ControllerBase
{
[ApiController]
[Route("api/take/assessment")]
public class StudentAssessmentController : ControllerBase
{
I found the cause. The last parameter for CreatedAtRoute and CreatedAtAction required an object similar to the destination controller. It went over my head because I was sending models prior to what I did now which used a ViewModel.
Well That wasn't the main reason I couldn't get a response though. It was because of an execption where the object I'm passing ended up having recursive references because I was sending a model that wasn't properly formatted to be sent over as JSON.
I used this to make it work, taken from the MS Docs site:
CreatedAtAction(String, String, Object, Object) Where the last parameter should be the object you want to the api to send over.
PS: I also didn't notice immediately because when I debugged the project, it didn't crash and had to read the logs. I'm a noob so I really didn't know that it's possible for an exception to occur without the project crashing in debug mode.
I have this Object
public class Deportista implements Serializable {
private static final long serialVersionUID = 6229604242306465153L;
private String id;
...
#NotNull(message="{field.null}")
public String getId() {
return id;
}
...
}
I have the following Controller's methods
#InitBinder(value="deportistaRegistrar")
public void registrarInitBinder(WebDataBinder binder) {
logger.info(">>>>>>>> registrarInitBinder >>>>>>>>>>>>>");
}
#RequestMapping(value="/registrar.htm", method=RequestMethod.GET)
public String crearRegistrarFormulario(Model model){
logger.info("crearRegistrarFormulario GET");
Deportista deportista = new Deportista();
model.addAttribute("deportistaRegistrar", deportista);
return "deportista.formulario.registro";
}
#RequestMapping(value="/registrar.htm", method=RequestMethod.POST)
public String registrarPerson(#Validated #ModelAttribute("deportistaRegistrar") Deportista deportista,
BindingResult result){
logger.info("registrarPerson POST");
logger.info("{}", deportista.toString());
if(result.hasErrors()){
logger.error("There are errors!!!!");
for(ObjectError objectError : result.getAllErrors()){
logger.error("Error {}", objectError);
}
return "deportista.formulario.registro";
}
logger.info("All fine!!!!");
this.fakeMultipleRepository.insertDeportista(deportista);
return "redirect:/manolo.htm";
}
Until here the Controller is able to create a form (GET) and submit (POST) a new command object, Validation code works well.
The problem is with the update.
I have the following:
#InitBinder(value="deportistaActualizar")
public void actualizarInitBinder(WebDataBinder binder) {
logger.info(">>>>>>>> actualizarInitBinder >>>>>>>>>>>>>");
binder.setDisallowedFields("id");
}
Observe I have binder.setDisallowedFields("id")
public String crearActualizarFormulario(#PathVariable("id") String id, Model model){
logger.info("crearActualizarFormulario GET");
Deportista deportista = this.fakeMultipleRepository.findDeportista(id);
model.addAttribute("deportistaActualizar", deportista);
return "deportista.formulario.actualizacion";
}
#RequestMapping(value="/{id}/actualizar.htm", method=RequestMethod.POST)
public String actualizarPerson(#Validated #ModelAttribute("deportistaActualizar") Deportista deportista,
BindingResult result){
logger.info("actualizarPerson POST");
logger.info("{}", deportista.toString());
if(result.hasErrors()){
logger.error("There are errors!!!!");
for(ObjectError objectError : result.getAllErrors()){
logger.error("Error {}", objectError);
}
return "deportista.formulario.actualizacion";
}
logger.info("All fine!!!!");
this.fakeMultipleRepository.updateDeportista(deportista);
return "redirect:/manolo.htm";
}
The problem is:
when the form or command has any error, the controller re-render the view and the form appear showing the error messages how is expected, but without the ID value
or
if I try to update the object, of course keeping the id value, and without any error to simply proceed to update, it fails
The following appears in the Console:
- -------- createCollections ---------------
- >>>>>>>> actualizarInitBinder >>>>>>>>>>>>>
- Skipping URI variable 'id' since the request contains a bind value with the same name.
- actualizarPerson POST
- Deportista [id=null, nombre=Manuel, ...]
- There are errors!!!!
- Error Field error in object 'deportistaActualizar' on field 'id': rejected value [null]; codes [NotNull.deportistaActualizar.id,NotNull.id,NotNull.java.lang.String,NotNull]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [deportistaActualizar.id,id]; arguments []; default message [id]]; default message [The field must be not empty]
The id is null. How I can around this problem keeping the Request Scope?
I have an alternate controller which is working with #SessionAttributes and all works perfect. But since is a huge risk if the user has many tabs open in the same web browser, one for create and other for updating, all is going to be very wrong. According with Spring MVC + Session attributes and multiple tabs, request scope should be used instead of session scope. It has sense.
Sadly seems Spring is not going to fix this:
#SessionAttributes doesn't work with tabbed browsing
Addition
According with your suggestion, I have the following:
#ModelAttribute("deportistaActualizar")
public Deportista populateActualizarFormulario(#RequestParam(defaultValue="") String id){
logger.info("populateActualizarFormulario - id: {}", id);
if(id.equals(""))
return null;
else
return this.fakeMultipleRepository.findDeportista(id);
}
Observe the method uses #RequestParam, my problem is how update that method to work when the URL to update has the following style
http://localhost:8080/spring-utility/deportista/1/actualizar.htm. There is no param in the URL, therefore #RequestParam is useless now.
I already have read the Spring Reference documentation:
Using #ModelAttribute on a method
Second Addition
Yes, you was right, and I did that yesterday, but I forget to share the following:
#ModelAttribute("deportistaActualizar")
public Deportista populateActualizarFormulario(#PathVariable(value="id") String id){
logger.info("populateActualizarFormulario - id: {}", id);
if(id.equals(""))
return null;
else
return this.fakeMultipleRepository.findDeportista(id);
}
Since a #ModelAttribute is called always before by any handler method, the following URL fails http://localhost:8080/spring-utility/deportista/registrar.htm, the following appears on the page
HTTP Status 400 -
type Status report
message
description The request sent by the client was syntactically incorrect.
Of course because the URL does not contains the expected id. Therefore I can't create new records to later edit/see.
I can confirm, that for the following work:
http://localhost:8080/spring-utility/deportista/1/detalle.htm
http://localhost:8080/spring-utility/deportista/1/actualizar.htm
the id (1) is retrieved.
How I could resolve this?
Thank You
I am really not sure if this is feasible using Spring 3.2 MVC.
My Controller has a method declared as below:
#RequestMapping(method = RequestMethod.GET)
#ResponseStatus(HttpStatus.OK)
public #ResponseBody List<Foo> getAll(){
return service.getAll();
}
Questions:
What is the meaning of #ResponseStatus(HttpStatus.OK) ?
Does it signifies that the method will always return a HttpStatus.OK status code.
What if an exception is thrown from the service layer?
Can I change the Response Status on occurrence of any exception?
How can I handle multiple response statuses depending on conditions in the same method?
#ResponseStatus(HttpStatus.OK) means that the request will return OK if the handling method returns normally (this annotation is redundant for this case, as the default response status is HttpStatus.OK). If the method throws an exception, the annotation does not apply; instead, the status will be determined by Spring using an exception handler.
How can I handle multiple response statuses depending on conditions in the same method?
That question has already been asked.
Can I change the Response Status on occurrence of any exception
You have two choices. If the exception class is one of your own, you could annotate the exception class with #ResponseStatus. The other choice is to provide the controller class with an exception handler, annotated with #ExceptionHandler, and have the exception handler set the response status.
If you return a ResponseEntity directly, you can set the HttpStatus in that:
// return with no body or headers
return new ResponseEntity<String>(HttpStatus.NOT_FOUND);
If you want to return an error other than 404, HttpStatus has lots of other values to choose from.
You cannot set multiple status value for #ResponseStatus. One approach I can think of is to use #ExceptionHandler for response status which is not HttpStatus.OK
#RequestMapping(value = "login.htm", method = RequestMethod.POST)
#ResponseStatus(HttpStatus.OK)
public ModelAndView login(#ModelAttribute Login login) {
if(loginIsValidCondition) {
//process login
//.....
return new ModelAndView(...);
}
else{
throw new InvalidLoginException();
}
}
#ExceptionHandler(InvalidLoginException.class)
#ResponseStatus(HttpStatus.BAD_REQUEST)
public ModelAndView invalidLogin() {
//handle invalid login
//.....
return new ModelAndView(...);
}