error when create service res.json is not a function

Question

I work on angular 7

I create service take array of locations then make forjoin between them 

but i get error as following :

error when create service res.json is not a function

 

core.js:15724 ERROR TypeError: res.json is not a function
    at MapSubscriber.project (part-details.service.ts:56)
    at MapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/map.js.MapSubscriber._next (map.js:35)
    at MapSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:54)
    at MapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/map.js.MapSubscriber._next (map.js:41)
    at MapSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:54)
    at FilterSubscriber.push../node_modules/rxjs/_esm5/internal/operators/filter.js.FilterSubscriber._next (filter.js:38)
    at FilterSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:54)
    at MergeMapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber.notifyNext (mergeMap.js:84)
    at InnerSubscriber.push../node_modules/rxjs/_esm5/internal/InnerSubscriber.js.InnerSubscriber._next (InnerSubscriber.js:15)
    at InnerSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:54)

and this is my code

      getLocationData(ids: Array<number>) {
        let observableBatch = [];

      ids.forEach((id) => {

            observableBatch.push(
                  this.http.get('http://192.168.7.45:9200/location/_doc/'+id)

                          .map((res: any) => res.json()));
        });

        return Observable.forkJoin(observableBatch);
    }

      //--------------------------------

}

 error show display here 

 

How to solve this problem please ?

 

I pass array of locationid to url to get gps1 

from json returned from function  then i mkae forkjoin between them