A form input & tabular output on the same page in Angular

So, I have started learning Angular. I like it as it enforces OOPs concepts via TypeScript.

Here I show how to input data into a form and display each entry as a row in a table.

angular-forms.png

import FormsModule into app.module.ts import { FormsModule } from '@angular/forms'; and place it into imports.

imports: [
    BrowserModule, FormsModule
  ],

Now place this HTML code in app.component.html

<div class="container">

    <form  class="mt-3" (ngSubmit)="addUser()" ngNativeValidate>
        <div class="form-row">
            <div class="form-group col-md-5">
                <input id="firstName" name="firstName" type="text" class="form-control" placeholder="First Name" [(ngModel)] = 'user.firstName' required />
            </div>
            <div class="form-group col-md-5">
                <input id="lastName" name="lastName" type="text" class="form-control" placeholder="Last Name" [(ngModel)] = 'user.lastName' required />
            </div>
            <div class="form-group col-md-2">
                <button type="submit" class="btn btn-primary">Save User</button>
            </div>
        </div>
    </form>

    <div class="table-responsive-sm">
        <table class="table">
            <thead>
                <tr>
                    <th>Firstname</th>
                    <th>Lastname</th>
                </tr>
            </thead>
            <tbody>              
                <ng-container *ngFor="let u of _users.reverse(); let i = index">
                <tr>
                    <td>{{ u.firstName }}</td>
                    <td>{{ u.lastName }}</td>
                  </tr>
              </ng-container>
            </tbody>          
        </table>
      </div>    

</div>

and this into app.component.ts (the only reason why I put class User into app.component.ts is for easy reference, otherwise this would be stored in a separate file and then imported into app)

import { Component } from '@angular/core';

export class User
{
    private _id: number;

    firstName: string;
    lastName: string;

    constructor(_id: number)
    {
        this._id = _id;
    }

    get id(): number
    {
        return this._id;
    }

    set id(id:number)
    {
        this._id = id;
    }

    setAllDetails(_firstName:string, _lastName: string)
    {
        this.firstName = _firstName;
        this.lastName = _lastName;
    }
}

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent
{
    _users:User[] = [];
    user:User;

    constructor()
    {        
        this.user = new User(0);
    }

    addUser()
    {
        this.user.id = Math.floor(Math.random() * 100000);

        // https://stackoverflow.com/questions/35959372/property-assign-does-not-exist-on-type-objectconstructor
        const newUser = (<any>Object).assign({}, this.user); // copy, -t es6

        // https://stackoverflow.com/questions/64566579/home-come-object-assign-works-for-sending-in-a-copy-of-the-object-to-a-function
        // const newUser = { ...this.user }; // This doesn't work since expected type in addUser() is user: User        
        // this._users.push(this.user);
        this._users.push(newUser);

        // this.service.addUser(newUser);
    }
}

Two issues :

  1. const newUser = { ...this.user } won't do as the resultant newUser won't have all the properties (like private properties and methods) which will result in a TypeScript error.
  2. this._users.push(this.user); will push a reference of this.user to the _users array which will have the exact values in all keys of the array. So it it necessary to pass in a copy of this.user to push() or any other function (like a service) that accepts a argument of type User.

Ref : stackoverflow.com/questions/64566579/home-c..

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