redux-observable wont be execute after catchError

Question

I am using redux-observable in my angular project. I have an updateNode function in my epics with catchError handling. I dispatch action DB_UPDATE_NODE many times and everything work well. However the time action execute catchError when I dispatch that action again, updateNode function wont be called any more.

public updateNode(action$: Observable<IScenarioNodesAction>, store: Store<IAppState>) {
  return action$.pipe(
    ofType(ScenarioNodeActionType.DB_UPDATE_NODE),
    flatMap((action) => {
     return  this._scenarioNodeService.update(action.payload.botId);
    }),
    flatMap(data => [
      this._scenarioNodeAction.updateNode(data),
    ]),
    catchError((error) => { 
      return Observable.of(this._commonAction.showError(error));
    })
  );
}

timdeschryver · Accepted Answer · 2018-09-13T08:59:51.647

2

You have to catch the error on the service's stream.

flatMap((action) => {
  return this._scenarioNodeService.update(action.payload.botId)
             .pipe(catchError(...)) ;
})

See the docs for more information.

Here we placed the catchError() inside our mergeMap(), but after our AJAX call; this is important because if we let the error reach the action$.pipe(), it will terminate it and no longer listen for new actions.

edited Sep 13 '18 at 08:59

answered Sep 13 '18 at 07:34

timdeschryver

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Thanks! but I faced with another error says I can not set value on setter :( – Amir Movahedi Sep 13 '18 at 08:48
I was wrong, you have to do this on the service call, I didn't see the second flatmap. See the updated answer – timdeschryver Sep 13 '18 at 08:59
I did on service but no result. – Amir Movahedi Sep 13 '18 at 09:15

Mac_W · Answer 2 · 2018-09-13T10:12:09.347

If your observable returns an errors it stops the observer from getting new events.

Please add to catchError something like:

  public updateNode(action$: Observable<IScenarioNodesAction>, store: Store<IAppState>){
    return action$.pipe(
      ofType(ScenarioNodeActionType.DB_UPDATE_NODE),
      flatMap((action) => {
       return  this._scenarioNodeService.update(action.payload.botId);
      }),
        flatMap(data => [
          this._scenarioNodeAction.updateNode(data),
        ]) ,
        catchError((error) => { 
              retryWhen((errors) => {
               return errors
                .pipe(delay(1000), take(1))
                .concat(Observable.throw(`Error`));
            },
        ),
      })
    );

  }

What the above does it waits a second delay(1000) and retries an amount of times take(1). If the error persists it throws error .concat(Observable.throw('Error')). In your case you just call showError and drop the connection.

Thanks! I have added to catch error but it's same happened again. Not sure but could you please show me how would my code when I add your code? Maybe I am wrong! — Amir Movahedi, Sep 13 '18 at 08:50
Thanks! I have changed but I have type error. `Type 'UnaryFunction, Observable<{}>>' is not assignable to type 'ObservableInput<{}>'.` — Amir Movahedi, Sep 14 '18 at 02:23

redux-observable wont be execute after catchError

2 Answers2