Angular 5 subscribe not assign data to list

Question

i am unable to assign data to my qMList. console always showing that list is undefined. web service is working and data is coming as observable problem is data not assigning to qMList.

@Injectable()
export class QuestionService {

  public qMList: QuestionMaster[] ;

    constructor(private http: HttpClient) {

    }

    getOsz():Observable<QuestionMaster[]>{

      return this.http.get<QuestionMaster[]>("http://localhost:7073/api/values");

    }

    getQuestions() {

      this.getOsz().subscribe(res => this.qMList = res);

      console.log(this.qMList);

      }
}

That's because getOsz is asynchronous, so the log statement is printing before qMList has been set — user184994
– user184994, Commented Apr 22, 2018 at 11:39
If you move your console.log into the subscribe, it'll print fine (subscribe(res => { this.qMList = res; console.log(this.qMList);})) — user184994
– user184994, Commented Apr 22, 2018 at 11:47

Katya Pavlenko · Accepted Answer · 2018-04-22 11:54:55Z

1

the problem is int he fact that http request is asyncronious and you should wait for it to fullfil

@Injectable()
export class QuestionService {

  public qMList: QuestionMaster[] ;

    constructor(private http: HttpClient) {

    }

    getOsz():Observable<QuestionMaster[]>{

      return this.http.get<QuestionMaster[]>("http://localhost:7073/api/values");

    }

    getQuestions() {

      this.getOsz().subscribe(res => {
            this.qMList = res;
            console.log(this.qMList);
      });

      }
}

answered Apr 22, 2018 at 11:54

Katya Pavlenko

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6 Comments

Suneth Athakada Over a year ago

how to do it synchronously?

Katya Pavlenko Over a year ago

there is no way to make request syncronious, why would you need it?

Suneth Athakada Over a year ago

i want to use for loop for qMList where i put console.log(this.qMList);.

Katya Pavlenko Over a year ago

so make a loop inside of the subscribe section

Suneth Athakada Over a year ago

in the subscribe section how to return qMList to another component.

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