In your product.service.ts you are using stringify method in a wrong way..

Just use

JSON.stringify(product) 

instead of

JSON.stringify({product})

i have checked your problem and after this it's working absolutely fine.

If you use a TypeScript interface instead of a class, things are simpler:

Copyexport interface Employee {
    typeOfEmployee_id: number;
    department_id: number;
    permissions_id: number;
    maxWorkHours: number;
    employee_id: number;
    firstname: string;
    lastname: string;
    username: string;
    birthdate: Date;
    lastUpdate: Date;
}

let jsonObj = JSON.parse(employeeString); // string to "any" object first
let employee = jsonObj as Employee;

If you want a class, however, simple casting won't work. For example:

Copyclass Foo {
    name: string;
    public pump() { }
}

let jsonObj = JSON.parse('{ "name":"hello" }');
let fObj = jsonObj as Foo;
fObj.pump(); // crash, method is undefined!

For a class, you'll have to write a constructor which accepts a JSON string/object and then iterate through the properties to assign each member manually, like this:

Copyclass Foo {
    name: string;

    constructor(jsonStr: string) {
        let jsonObj = JSON.parse(jsonStr);
        for (let prop in jsonObj) {
            this[prop] = jsonObj[prop];
        }
    }
}

let fObj = new Foo(theJsonString);

you can use class-transformer which helps you to convert plain javascript objects to real es6 classes. With this real instances you can also use class methods.

import { Component, OnInit } from "@angular/core";
import ProductsJson from "./products.json";
import {plainToClass} from "class-transformer";

@Component({
  selector: "my-app",
  templateUrl: "./app.component.html",
  styleUrls: ["./app.component.css"]
})
export class AppComponent implements OnInit {
  productsJson: any = ProductsJson;
  products: Array<Product>;
  constructor() {}
  ngOnInit() {
    //this.products = <Product[]>this.productsJson;
    this.products = plainToClass(Product, this.productsJson as []);
    console.log(this.products);
  }
}
export class Product {
  id: number;
  name: string;
  description: string;
  relatedProducts: Array<number>;

  getId(){
    return this.id + "_ID";
  }
}

template:

<ul>
    <li *ngFor="let p of products">
        {{p.getId()}} {{p.id}} {{p.name}}
    </li>
</ul>

You can do it with angular.fromJson()

in your sample, it would have been $scope.tmp = angular.fromJson($scope.text);

The difference between JSON.Parse() and angular.fromJson, is that angular will check to make sure a string is provided. If it is already an object, it will return the same object.

You are passing the data as a parameter, hence you should not use $scope prefix. Instead just use data.

  $scope.updateDetails = function (data) {
                        $scope.editedArrayDetails = [];
                        $scope.editedArrayDetails.push(data);
                        $scope.json = angular.toJson(data);
                        console.log($scope.json )
                        $scope.goEvent();
                    }

As Abdul has pointed out you have a JSON array and you want a JSON object, there you need

  var eachProduct = 
                     {
                         "name": name,
                         "id": id,
                         "category":category,
                         "price":price
                     };

Now alert(eachProduct.name); will return name. And I assume by "How to pass the function parameters to the each product" you mean add an attribute to your JSON object. To do this you you would have

eachProduct["someAttribute"]='"value":someValue';