Struggling to assign the data value retrieved from an API to a class variable in Angular 8

As I call the api to fetch data in the ngOnInit lifecycle hook, I am struggling with assigning the retrieved data to a class variable. Here is the relevant code snippet:

  tasks: Task[];

  ngOnInit() {

    this.apiService.getTasks()
      .subscribe( data => {
        Object.keys(data).map((index) => {
          this.tasks.push(data[index]);
       });
      });

  }

An error message 'TypeError: Cannot read property 'push' of undefined' keeps appearing for the line:

this.tasks.push(data[index]);

Even though 'tasks' has been defined as an array.

I could really use some help understanding the scope here, any suggestions would be greatly appreciated.

Answer №1

If your main goal in the map is simply to retrieve the property's value, you have the option of utilizing Object.values().

this.apiService.getTasks().subscribe(data => {
  this.tasks = Object.values(data);
});

Answer №2

A revised approach is to utilize the map method for returning a new array, eliminating the need for manual pushing. Consider updating your code as follows:

this.apiService.getTasks()
      .subscribe( data => {
        this.tasks = Object.keys(data).map((index) => {
         return data[index];
         });
      });

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