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observable undefined in component - Angular

I have a service that connects with api
export class ConsolidadoApi {
constructor(private http: HttpClient) { }
getInvestiments(search?: any): Observable<any> {
return this.http.get<any>(`${environment.basePosicaoConsolidada}`);
}
}
Response this api:
https://demo5095413.mockable.io/consolidado
This one is responsible for the logic before reaching the component
#Injectable({
providedIn: 'root'
})
export class CoreService {
public test;
constructor(private api: ConsolidadoApi, private state: StateService) { }
public createMenu() {
this.api.getInvestiments()
.subscribe(response => {
console.log(response.carteiras[0])
this.products = response.carteiras[0]
return this.products;
})
}
In my component
export class MenuComponent implements OnInit {
constructor( private coreService : CoreService ) {}
ngOnInit(): void {
console.log(this.coreService.createMenu())
}
}
But when createMenu is called in menu.component.ts it comes undefined.

The raw response is an object. forEach works only on an array. If you are aiming for forEach in 'categorias', you should try
this.test.categorias.forEach()

When you return Observable<any>, that means the argument of the lambda you create when you do subscribe (which you named response) is type any. This doesn't necessary have the function forEach defined (unless the API returns an object with that prototype). That's generally why using any is not good practice; you can't have any expectations on what the object can contain. In fact, it's possible that it's not on object (it could be an array since any is not exclusively an object). If you do want to use forEach, you will want to make sure that response is type array. You can inspect the object's type before using it (e.g. using typeof) and make a judgement on what to call or even just check if the function you're trying to use is defined first, e.g. if (response.forEach !== undefined). You don't actually need to compare to undefined though, so if (response.forEach) suffices. In the examples, I used response, but you can use this.test since they are the same object after the first line in the lambda.

Based on the link you shared, the response is an object. You can log it to the console to confirm.
You can only call for each on an array, so for example, based on the response api, you can call forEach on the property ‘categorias’ and on that array’s children property ‘produtus’
Edit: this answer was based on the op original api and question
https://demo5095413.mockable.io/carteira-investimentos
public createMenu() {
return this.api.getInvestiments()
}
ngOnit() {
this.coreService.createMenu().subscribe(x => console.log(x.categorias))};
{
"codigo":1,
"categorias":[
{
"nome":"Referenciado",
"valorTotal":23000.0,
"codigo":"2",
"produtos":[
{
"nome":"CDB Fácil Bradesco",
"valor":2000.0,
"codigo":1,
"quantidade":0.0,
"porcentagem":0.5500,
"aplicacaoAdicional":500.0,
"codigoInvest":1,
"salaInvestimento":"CDB",
"permiteAplicar":true,
"permiteResgatar":true,
"movimentacaoAutomatica":false,
"ordemApresentacao":37,
"horarioAbertura":"08:30",
"horarioFechamento":"23:59",
"codigoGrupo":0,
"codigoMF":"001

angular load local file then make http calls to return observables

I am new to Angular, JS, and observables. I have a typescript class called DataService. I want it to load a list of URLs from a JSON formatted local file, and then have some way to call those URLs (to a handful of REST APIs) and return observables. The problem I am having is my code is not waiting for the config file to be loaded before the REST API functions get called.
I thought I could have the DataService constructor load the configuration file, and then have unique functions for each REST API call, but that isn't working
my code:
export class DataService {
configFile
constructor(private http: HttpClient) {
this.http.get('/assets/restApiUrlListConfig.json').subscribe(config => {
this.configFile = config;
});
}
getUrlFromConfigFile(name: string): string {
...
this returns the URL from the config file
...
}
getUrlAData(): Observable {
return this.http.get( getUrlFromConfigFile('A') )
}
}
My other components have code like this:
export class SomeComponent implements OnInit {
someComponentAData
constructor(private data: DataService) { }
ngOnInit() {
this.data.getUrlAData().subscribe(
data => {
this.someComponentAData = data
}
)
}
I am getting an error that the observable returned from the dataservice is undefined. Which I believe is because the constructor hasn't finished loading the config file, which I think is why the function getUrlAData isn't returning anything.
I feel like I'm not correctly handling these async calls, but I'm at a loss for how to tell my code to :
create the data service object
load the data file before anything else can be done
allow the other functions to be called asyncronously AFTER the config file is loaded
Angular CLI: 6.2.3
Node: 8.12.0
OS: win32 x64
Angular: 6.1.8
Edit 1: attempting to implement suggested solution
My DataService
configFile
configObservable: Observable<any>;
someSubscribeObj
constructor(private http: HttpClient) {
this.someSubscribeObj = this.http.get('/assets/restApiUrlListConfig.json').subscribe(config => {
this.someSubscribeObj = undefined;
this.configFile = config;
});
}
getObsFromConfigFile(name: string): Observable<any> {
//...
if (this.configFile != undefined) {
console.log('this.restApiUrlListConfig[name]',this.configFile[name])
return of(this.configFile[name])
}
else
return of(this.someSubscribeObj.pipe(map(c => c[name])))
//this.configObservable
//...
}
getUrlAData(): Observable<any> {
return this.getObsFromConfigFile('A').pipe(mergeMap(url => this.http.get(url)))
}
My other component:
constructor( private data: DataService ) { }
ngOnInit() {
//this.data.loggedIn.pipe((p) => p);
this.data.getUrlAData().subscribe(
data => {
this.urlAData = data
}
)
}
I was unable to store the "subscribe" into the observable, so I created a generic Any type varable, but at runtime I get a problem with the pipe command:
TypeError: this.someSubscribeObj.pipe is not a function
at DataService.push../src/app/services/data.service.ts.DataService.getObsFromConfigFile
(data.service.ts:67)
at DataService.push../src/app/services/data.service.ts.DataService.getUrlAData
(data.service.ts:74)
Edit 2: the unfortunate workaround
I am currently using two nested subscriptions to get the job done basically
http.get(config_file_url).subscribe(
config => {
http.get( config['A'] ).subscribe( adata => { do things };
http.get config['B'].subscribe( bdata => {do things };
}
)
I feel like I should be able to use a mergeMap of some sort, but I couldn't get them to work as I thought they would.

You need to wait on that async call, I would use a flatmap to get the value out of an observable.
export class DataService {
configFile
configObservable: Observable<any>;
constructor(private http: HttpClient) {
this.configObservable = this.http.get('/assets/restApiUrlListConfig.json').pipe(
map(config => {
this.configObservable = undefined;
this.configFile = config;
return configFile;
})
);
}
getUrlFromConfigFile(name: string): Observable<string> {
...
return of(configFile[name]) if configFile is set else return configObservable.pipe(map(c => c[name]));
...
}
getUrlAData(): Observable<string> {
return this.getUrlFromConfigFile('A').pipe(map(url => this.http.get(url)))
}
}
Basically you want to store the observable and keep using it till it completes, after it completes you can just wrap the config in an observable. The reason for wrapping it is to make the interface consistent, otherwise you have to have an if before every get.

Shared service works only onInit - Angular

I want to pass an object between 2 components. I created the following shared service:
[PageService Component]
private messageSource = new BehaviorSubject([]);
currentMessage = this.messageSource.asObservable();
changeMessage(message) {
this.messageSource.next(message)
}
And I have implemented it in these 2 components:
[COMPONENT WHEN I GET ON CLICK SONO DATAS]
constructor(private pageService: PageService, private _sanitizer: DomSanitizer) {}
...
onClickMethod(){
self.pageService.getCustomers(self.filters).toPromise().then(response => {
self.searchResults = response;
});
self.pageService.changeMessage(self.searchResults);
}
and
[Component where I need to see above datas]
ngOnInit() {
let self = this;
self.pageService.currentMessage.subscribe(message => self.searchResults = message);
console.log(self.searchResults);
}
Now...if I put the "changeMessage" method in the first component in the method onInit or in the costructor and i try to pass some data like [1,2,3] (so not the response of another api rest) it seems to work...this doesn't work just when i put it inside onClick method and passing "self.searchResults" (the response)...anyone can help me?
Thanks

Go from this
self.pageService.getCustomers(self.filters).toPromise().then(response => {
self.searchResults = response;
});
self.pageService.changeMessage(self.searchResults);
To this
self.pageService.getCustomers(self.filters).toPromise().then(response => {
self.searchResults = response;
self.pageService.changeMessage(self.searchResults);
});
Because you make an HTTP call (I assume), you should wait for the call to end. In your code, it doesn't.

Angular HttpClient get, wrong this object

in my Angular App i make a simple call to a node.js server. the HttpClient "get"
function returns the right answer. This answer I want to store in a variable of my component "interfaces". But in the "subscribe" function of the get request my "this" pointer doesn't point to my component. Instead it tells me that it is of type "SafeSubscriber". Any call to my member "interfaces" lead to the following error:
TypeError: Cannot read property 'interfaces' of undefined
export class SettingsComponent implements OnInit {
public interfaces : string[];
constructor(private http: HttpClient) {
this.interfaces = [];
this.interfaces.push("huhu");
}
ngOnInit() : void {
this.http.get('http://localhost:3000/settings/interfaces').subscribe((data) => {
// Read the result field from the JSON response.
console.log(data);
this.interfaces.push("xxx");
Object.keys(data).forEach(function(k) {
console.log(k);
this.interfaces.push("xxx");
});
}),
err => {
console.log("error " + err);
};
}
}
As you can see I also tried to enter some values manually into the array just to make sure, that not the server response is causing the problem.
Any help is appreciated.
I used this code as a blueprint which is from:
https://angular.io/guide/http
#Component(...)
export class MyComponent implements OnInit {
results: string[];
// Inject HttpClient into your component or service.
constructor(private http: HttpClient) {}
ngOnInit(): void {
// Make the HTTP request:
this.http.get('/api/items').subscribe(data => {
// Read the result field from the JSON response.
this.results = data['results'];
});
}
}

You're losing reference to the correct this in this statement:
Object.keys(data).forEach(function(k) {..})
Inside the function block code this refers to the calling context , which is the subscribe method itself, that's why interfaces is undefined, since it's not a property of the subscribe method.
You can change the function for a lambda en it should be fine:
Object.keys(data).forEach((k) => {..})

Angular 2 - Component property undefined in method

I have a property that is a custom class array. The array is populated with a call to a service which calls a web service for data. I have subscribed to the observable and I'm using the complete event to fire off a method which loads a graph.
The data the graph uses should come from the array which is populated during the subscribe, but when I attempt to do so in the method I am getting an undefined error on my component property. Why is this the case, I though that the component property should be accessible to methods in the same class.
export class MetricsComponent implements OnInit{
errorMessage: string;
metric: MetricData[] = [];
//constructor is used for dependency injection
constructor(public _metricsService: MetricsService){}
ngOnInit(): void {
console.log('talking to service...');
this._metricsService.getData()
.subscribe(
data => this.metric = data,
error => this.errorMessage = <any>error,
this.LoadChart
);
}
LoadChart(): void {
console.log(this.metric); // <== this returns as undefined
}

Use arrow functions to retain the scope of this.
ngOnInit(): void {
console.log('talking to service...');
this._metricsService.getData()
.subscribe(
data => this.metric = data,
error => this.errorMessage = <any>error,
() => this.LoadChart()
);
}

do it like this for more info read about lexical this and arrow functions one more thing if you are using chrome developer tools it will still show null there is some bug with chrome developer tools.
LoadChart = () => void {
console.log(this.metric); //
}