Angular 4 - Observable catch error

Question

How can I solve the problem of return with error, use the capture inside the Observable?

I want to execute a function inside the catch, to do some validation before the subscribe is executed.

Thank you in advance, thank you very much for your attention.

Error occurs in -> .catch( (e) => {console.log(e)} )

import { Injectable } from '@angular/core'; import { Headers, Http, ResponseOptions} from '@angular/http'; import { AuthHttp } from 'angular2-jwt';  import { MEAT_API } from '../app.api';  import { Observable } from 'rxjs/Observable'; import 'rxjs/add/operator/map'; import 'rxjs/add/operator/catch';  @Injectable() export class  CompareNfeService {       constructor(private http: AuthHttp) { }      envirArquivos(order): Observable<any> {         const headers = new Headers();         return this.http.post(`${MEAT_API}compare/arquivo`, order,         new ResponseOptions({headers: headers}))         .map(response => response.json())         .catch( (e) => {console.log(e)} );     } } 

Error

ERROR in /XXXXXX/application/src/app/compare/service.ts (28,17): Argument of type '(e: any) => void' is not assignable to parameter of type '(err: any, caught: Observable) => ObservableInput<{}>'.
Type 'void' is not assignable to type 'ObservableInput<{}>'.

Answer 1

If you want to use the catch() of the Observable you need to use Observable.throw() method before delegating the error response to a method

import { Injectable } from '@angular/core';  import { Headers, Http, ResponseOptions} from '@angular/http';  import { AuthHttp } from 'angular2-jwt';    import { MEAT_API } from '../app.api';    import { Observable } from 'rxjs/Observable';  import 'rxjs/add/operator/map';  import 'rxjs/add/operator/catch';    @Injectable()  export class CompareNfeService {        constructor(private http: AuthHttp) {}      envirArquivos(order): Observable < any > {      const headers = new Headers();      return this.http.post(`${MEAT_API}compare/arquivo`, order,          new ResponseOptions({            headers: headers          }))        .map(response => response.json())        .catch((e: any) => Observable.throw(this.errorHandler(e)));    }      errorHandler(error: any): void {      console.log(error)    }  }

Using Observable.throw() worked for me