How to create array of objects from another class in angular?

Question

I have two angular classes called class A , B and I have an angular component

export class B {
    id:String;
    Name:String;
}

My class A , Where I am passing data from a component. Where Component retrieves the data from httpclient request. Additionally I am trying to create an array of objects of class B . Which will have the size of data

export class A {

  mygroupB : B[];

  setData(data:any){
      if((data.length) >0){
        this.mygroupB = new B[data.length];
      }else return;

  }
}

But When I am running the code I am getting an error "B[data.length] is not a constructor" . I can't figure out, what is the mistake here. Thanks in advance.

you should create object as new B(); don't pass any arguments as your class B has no constructer to accept it.You can use map or loops to create a array — Madhawa Priyashantha
– Madhawa Priyashantha, Commented Sep 7, 2021 at 1:59
This is not java, you don't create array like that in javascript or typescript. Just this.mygroupB = []; is enough. — Ricky Mo
– Ricky Mo, Commented Sep 7, 2021 at 2:05

dom.macs · Accepted Answer · 2021-09-07 02:18:11Z

1

The first issue is you didn't instantiate your mygroupB before assigning the value. The next issue is you are trying to assign the value of data which is type any directly to mygroupB which has a type of B.

In the solution below, I instantiated mygroupB before iterating the values of data and then pushing it to the mygroupB array.

setData(data: any) {
    if (data.length > 0) {
      this.mygroupB = new Array<B>();
      data.forEach(e => {
        this.mygroupB.push({
          Name: e.Name,
          id: e.id
        });
      });
      console.log(this.mygroupB);
    }
}

edited Sep 7, 2021 at 2:18

answered Sep 7, 2021 at 2:05

dom.macs

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1 Comment

dom.macs Over a year ago

I'm glad I could help!

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