Why I don't need to JSON.stringify() this post payload?

Question

I have read:

How to post json object with Http.post (Angular 2) (php server side)

And both suggests to create headers and stringfy my object to JSON before doing a POST request, which works, but I noticed that if I just pass the object it works also fine.

So I'm just wondering who is responsible for this behaviour, 'cause I believe some layer is converting the object to JSON format. Or not?

I am using:

Angular 4 front-end.
Wildfly 10.1.0 final
Resteasy 3.1.1 final

I have a person.component.ts with the following method:

addPerson() {
    this.personService.save(this.person)
       .then(result => {
        console.log('Added!', result);
       });
  }

a person.service.ts with the save method:

save(person: Person){
    //OPTION 3
    return this.http.post(`${this.baseURL}person/add`, person).toPromise();
}

Backend I have my REST application class:

@ApplicationPath("/rest")
public class HouseApplication extends Application {

    public HouseApplication() {}
}

and my Person resource:

@RequestScoped
@Path("/person")
@Produces({ "application/json" })
@Consumes({ "application/json" })
public class PersonResource {

    public PersonResource() {}

    @Inject
    PersonService personService;

    @POST
    @Path("/add")
    public void addPerson(Person person) throws HouseValidationException{
        personService.add(person);
    }
    ...

I'm actually getting an exception in the front-end but my record gets persisted to the database. I think the exception is related to the button I'm using, or the PRIMEng UI component in my screen...

I have the following messages in my console after the call:

ERROR Error: Uncaught (in promise): Unexpected literal at position 2
    at resolvePromise (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:710:31) [angular]
    at eval (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:761:17) [angular]
    at Object.onInvokeTask (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4322:37) [angular]
    at drainMicroTaskQueue (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:591:35) [<root>]
    at HTMLButtonElement.ZoneTask.invoke (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:464:25) [<root>]
    at ____________________Elapsed_3_ms__At__Fri_May_05_2017_02_45_38_GMT_0300__BRT_ (http://localhost)
    at getStacktraceWithUncaughtError (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:39:12) [angular]
    at new LongStackTrace (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:33:22) [angular]
    at Object.onScheduleTask (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:109:22) [angular]
    at Object.onScheduleTask (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:274:29) [angular]
    at scheduleResolveOrReject (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:756:14) [angular]
    at ZoneAwarePromise.then (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:845:17) [angular]
    at NgModel._updateValue (eval at <anonymous> (http://localhost:8080/house/vendor.js:72:1), <anonymous>:4434:27) [angular]
    at NgModel.ngOnChanges (eval at <anonymous> (http://localhost:8080/house/vendor.js:72:1), <anonymous>:4316:18) [angular]
    at checkAndUpdateDirectiveInline (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:10907:19) [angular]
    at checkAndUpdateNodeInline (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12289:17) [angular]
    at checkAndUpdateNode (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12257:16) [angular]
    at debugCheckAndUpdateNode (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12886:59) [angular]
    at debugCheckDirectivesFn (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12827:13) [angular]
    at Object.eval [as updateDirectives] (ng:///AppModule/PatientComponent.ngfactory.js:2577:5) [angular]
    at Object.debugUpdateDirectives [as updateDirectives] (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12812:21) [angular]
    at checkAndUpdateView (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12224:14) [angular]
    at callViewAction (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12539:17) [angular]
    at execComponentViewsAction (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12485:13) [angular]
    at checkAndUpdateView (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12230:5) [angular]
    at callViewAction (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12539:17) [angular]
    at execComponentViewsAction (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12485:13) [angular]
    at checkAndUpdateView (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12230:5) [angular]
    at callWithDebugContext (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:13212:42) [angular]
    at Object.debugCheckAndUpdateView [as checkAndUpdateView] (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12752:12) [angular]
    at ViewRef_.detectChanges (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:10321:63) [angular]
    at eval (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:5258:63) [angular]
    at Array.forEach (native) [angular]
    at ApplicationRef_.tick (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:5258:25) [angular]
    at eval (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:5138:106) [angular]
    at Object.onInvoke (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4331:37) [angular]
    at NgZone.run (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4200:62) [angular]
    at Object.next (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:5138:82) [angular]
    at SafeSubscriber.schedulerFn [as _next] (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4034:52) [angular]
    at SafeSubscriber.__tryOrUnsub (eval at <anonymous> (http://localhost:8080/house/vendor.js:28:1), <anonymous>:236:16) [angular]
    at SafeSubscriber.next (eval at <anonymous> (http://localhost:8080/house/vendor.js:28:1), <anonymous>:185:22) [angular]
    at Subscriber._next (eval at <anonymous> (http://localhost:8080/house/vendor.js:28:1), <anonymous>:125:26) [angular]
    at Subscriber.next (eval at <anonymous> (http://localhost:8080/house/vendor.js:28:1), <anonymous>:89:18) [angular]
    at EventEmitter.Subject.next (eval at <anonymous> (http://localhost:8080/house/vendor.js:79:1), <anonymous>:55:25) [angular]
    at EventEmitter.emit (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4020:76) [angular]
    at NgZone.checkStable (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4296:40) [angular]
    at NgZone.onLeave (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4372:14) [angular]
    at Object.onInvokeTask (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4325:27) [angular]
    at HTMLButtonElement.ZoneTask.invoke (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:460:38) [<root>]
    at ____________________Elapsed_18597_ms__At__Fri_May_05_2017_02_45_19_GMT_0300__BRT_ (http://localhost)
    at getStacktraceWithUncaughtError (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:39:12) [angular]
    at new LongStackTrace (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:33:22) [angular]
    at Object.onScheduleTask (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:109:22) [angular]
    at Object.onScheduleTask (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:274:29) [angular]
    at zoneAwareAddListener (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:1453:14) [angular]
    at HTMLButtonElement.addEventListener (eval at createNamedFn (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1)), <anonymous>:3:43) [angular]
    at DomEventsPlugin.addEventListener (eval at <anonymous> (http://localhost:8080/house/vendor.js:186:1), <anonymous>:3131:17) [angular]
    at EventManager.addEventListener (eval at <anonymous> (http://localhost:8080/house/vendor.js:186:1), <anonymous>:2477:23) [angular]
    at EmulatedEncapsulationDomRenderer2.DefaultDomRenderer2.listen (eval at <anonymous> (http://localhost:8080/house/vendor.js:186:1), <anonymous>:2990:36) [angular]
    at DebugRenderer2.listen (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:13476:30) [angular]
    at listenToElementOutputs (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:9558:66) [angular]
    at createViewNodes (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12148:17) [angular]
    at callViewAction (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12546:13) [angular]
    at execComponentViewsAction (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12485:13) [angular]
    at createViewNodes (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12203:5) [angular]
    at callViewAction (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12546:13) [angular]
    at execComponentViewsAction (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12485:13) [angular]
    at createViewNodes (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12203:5) [angular]
    at createRootView (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12081:5) [angular]
    at callWithDebugContext (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:13212:42) [angular]
    at Object.debugCreateRootView [as createRootView] (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:12673:12) [angular]
    at ComponentFactory_.create (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:10017:46) [angular]
    at ComponentFactoryBoundToModule.create (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:3633:29) [angular]
    at ApplicationRef_.bootstrap (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:5215:57) [angular]
    at eval (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:5002:79) [angular]
    at Array.forEach (native) [angular]
    at PlatformRef_._moduleDoBootstrap (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:5002:42) [angular]
    at eval (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4964:27) [angular]
    at Object.onInvoke (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4331:37) [angular]
    at eval (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:758:57) [angular]
    at Object.onInvokeTask (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4322:37) [angular]
    at drainMicroTaskQueue (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:591:35) [<root>]
    at <anonymous> [<root>]
    at ____________________Elapsed_62_ms__At__Fri_May_05_2017_02_45_19_GMT_0300__BRT_ (http://localhost)
    at getStacktraceWithUncaughtError (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:39:12) [angular]
    at new LongStackTrace (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:33:22) [angular]
    at Object.onScheduleTask (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:109:22) [angular]
    at Object.onScheduleTask (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:274:29) [angular]
    at scheduleResolveOrReject (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:756:14) [angular]
    at resolvePromise (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:705:21) [angular]
    at eval (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:758:17) [angular]
    at Object.onInvokeTask (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4322:37) [angular]
    at drainMicroTaskQueue (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:591:35) [<root>]
    at <anonymous> [<root>]
    at ____________________Elapsed_4_ms__At__Fri_May_05_2017_02_45_19_GMT_0300__BRT_ (http://localhost)
    at getStacktraceWithUncaughtError (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:39:12) [angular]
    at new LongStackTrace (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:33:22) [angular]
    at Object.onScheduleTask (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2776:1), <anonymous>:109:22) [angular]
    at Object.onScheduleTask (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:274:29) [angular]
    at scheduleResolveOrReject (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:756:14) [angular]
    at ZoneAwarePromise.then (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:845:17) [angular]
    at new ApplicationInitStatus (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:3120:60) [angular]
    at AppModuleInjector.createInternal (ng:///AppModule/module.ngfactory.js:167:35) [angular]
    at AppModuleInjector.NgModuleInjector.create (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:3743:76) [angular]
    at NgModuleFactory.create (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:3716:18) [angular]
    at eval (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4954:61) [angular]
    at Object.onInvoke (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4331:37) [angular]
    at NgZone.run (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4200:62) [<root>]
    at PlatformRef_._bootstrapModuleFactoryWithZone (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4952:23) [<root>]
    at eval (eval at <anonymous> (http://localhost:8080/house/vendor.js:14:1), <anonymous>:4993:59) [<root>]
    at eval (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:758:57) [<root>]
    at drainMicroTaskQueue (eval at <anonymous> (http://localhost:8080/house/polyfills.js:2782:1), <anonymous>:591:35) [<root>]
    at <anonymous> [<root>]
defaultErrorLogger @ core.es5.js?0445:1290
ErrorHandler.handleError @ core.es5.js?0445:1350
next @ core.es5.js?0445:4960
schedulerFn @ core.es5.js?0445:4034
SafeSubscriber.__tryOrUnsub @ VM28777:236
SafeSubscriber.next @ VM28777:185
Subscriber._next @ VM28777:125
Subscriber.next @ VM28777:89
Subject.next @ VM28804:55
EventEmitter.emit @ core.es5.js?0445:4020
NgZone.triggerError @ core.es5.js?0445:4391
onHandleError @ core.es5.js?0445:4352
ZoneDelegate.handleError @ zone.js?fad3:369
Zone.runGuarded @ zone.js?fad3:141
_loop_1 @ zone.js?fad3:602
drainMicroTaskQueue @ zone.js?fad3:611
ZoneTask.invoke @ zone.js?fad3:464
person.component.ts?10bd:76 '

Added! Response {_body: null, status: 204, ok: true, statusText: "No Content", headers: Headers…}

Note at the end of the console message that I have logged the message 'Added!' and the response which is fine.

So again, why I didn't need to stringfy my Person object, nor even set the Content-Type to application/json value but it got understood by the REST endpoint where it should only consume application/json content?

Any ideas? What did I miss?

score 1 · Accepted Answer · answered May 05 '17 at 06:28

1

If you trace down the http source code

detectContentTypeFromBody method will do the content setting for you

as detectContentType methods default case inside the switch

https://github.com/angular/angular/blob/master/packages/http/src/static_request.ts#L135

answered May 05 '17 at 06:28

eko

39,722
10
72
98

1

I see, so Angular is taking care of that, wouldn't it be better to just let it break? It might "teach" newbies in the wrong way, or more of an incomplete way... – skinny_jones May 05 '17 at 16:04
@skinny_jones I see your point. But some newbies get frustrated and give up on the framework the minute they see the red lines. I'm sure you know what I mean ;) – eko May 05 '17 at 16:30

Why I don't need to JSON.stringify() this post payload?

1 Answers1