Can't access method from the model class in Angular 4

Question

I am trying to use method from the model class but its throwing error like

ERROR TypeError: act.sayHi is not a function

Here is my code

Model Class myModelClass.ts

    export interface IMymodel {
        name: string;
        address: string;
        age: number;
    }

    export class Mymodel implements IMymodel {
        name: string;
        address: string;
        age: number 

        constructor() {}

        sayHi(name): string {
            console.log('Hiii' + name);
            return 'Hiii'+name;
        }

    }

Component MyComponent.ts

import { IMymodel, Mymodel } from '../model/myModelClass.ts';

@Component({
    selector: 'my-component',
    templateUrl: 'myComponent.html'
})
export class MyComponent {

    ...

    prepareData(data: Array<IMymodel>): Array<IMymodel> {

         data.map((act: Mymodel) => {
             act.sayHi(act.name);
         });

         return data;
    } 

}

Answer 1

You need to put the sayHi method signature into the interface too as you access your objects via interface type and that type lacks a method with name sayHi .

export interface IMymodel {
    name: string;
    address: string;
    age: number;
    sayHi(name): string
}

and method call

prepareData(data: Array<IMymodel>): Array<IMymodel> {

     data.map((act: IMymodel) => {
         act.sayHi(act.name);
     });

     return data;
}