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 lt any gt            const headers   new Headers            return this http post    MEAT API compare arquivo   order          new ResponseOptions  headers  headers             map response   gt  response json             catch   e    gt   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 lt         Type  void  is not assignable to type  ObservableInput lt

User · Answer

catch needs to return an observable    catch e   gt    console log e   return Observable of e        if you d like to stop the pipeline after a caught error  then do this    catch e   gt    console log e   return Observable of null      filter e   gt    e    this catch transforms the error into a null val and then filter doesn t let falsey values through   This will however  stop the pipeline for ANY falsey value  so if you think those might come through and you want them to  you ll need to be more explicit   creative   edit   better way of stopping the pipeline is to do   catch e   gt  Observable empty

User · Answer

You should be using below  return Observable throw error     Internal Server error      Import the throw operator using the below line  import  rxjs add observable throw

User · Answer

With angular 6 and rxjs 6 Observable throw    Observable off   has been deprecated instead you need to use throwError  ex     return this http get  yoururl      pipe      map response   gt  response json         catchError  e  any    gt           do your processing here       return throwError e

User · Answer

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   x000D   x000D  import   Injectable   from   angular core   x000D  import   Headers  Http  ResponseOptions  from   angular http   x000D  import   AuthHttp   from  angular2-jwt   x000D   x000D  import   MEAT API   from     app api   x000D   x000D  import   Observable   from  rxjs Observable   x000D  import  rxjs add operator map   x000D  import  rxjs add operator catch   x000D   x000D   Injectable   x000D  export class CompareNfeService   x000D   x000D   x000D    constructor private http  AuthHttp     x000D   x000D    envirArquivos order   Observable  lt  any  gt    x000D      const headers   new Headers    x000D      return this http post    MEAT API compare arquivo   order  x000D          new ResponseOptions   x000D            headers  headers x000D              x000D         map response   gt  response json    x000D         catch  e  any    gt  Observable throw this errorHandler e     x000D      x000D   x000D    errorHandler error  any   void   x000D      console log error  x000D      x000D    x000D   x000D   x000D    Using Observable throw   worked for me

[angular] Angular 4 - Observable catch error

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