====== Add Dialog Component from Angular Material ======
===== Basic Dialog =====
  - Install @angular/material by npm command.
  - Create a new component by ng g c command.
  - Assume the name of the new component is AlertDialogComponent, and it only display an alert message with an OK button. The TS file would be: (Note: this constructor take a ''data'' parameter)<code>
import {Component, Inject} from '@angular/core';
import {MAT_DIALOG_DATA, MatDialogRef} from "@angular/material";

@Component({
  selector: 'app-alert-dialog',
  templateUrl: './alert-dialog.component.html',
  styleUrls: ['./alert-dialog.component.css']
})
export class AlertDialogComponent {

  constructor(public dialogRef: MatDialogRef<AlertDialogComponent>,
              @Inject(MAT_DIALOG_DATA) public data: any) {
    console.log(data);
  }

  onOKClick(): void {
    this.dialogRef.close();
  }
}
</code>
  - The HTML file would be:<code><div mat-dialog-content>
  <p>{{data.message}}</p>
</div>
<div mat-dialog-actions>
  <button mat-button style="float: right" class="btn btn-primary"(click)="onOKClick()">OK</button>
</div>
</code>
  - Once the component is completed, we need to add it in a module. If this is use in the whole project, import it in the root module.<code>
...;
import {AlertDialogComponent} from "@app/shared/alert-dialog/alert-dialog.component";
export const appConfig = {
  declarations: [
    ...,
    AlertDialogComponent
  ],
  imports: [
    ...,
  ],
  entryComponents:[
    ...,
    AlertDialogComponent],
  providers: [...],
  bootstrap: [AppComponent]
</code>
  - To use the alert dialog in your component, import it:<code>
...;
import {AlertDialogComponent} from "@app/shared/alert-dialog/alert-dialog.component";
import {MatDialog} from "@angular/material";

</code>
  - Then inject a MatDialog in your component constructor:<code>
  constructor(public dialog: MatDialog) {}
</code>
  - To show up the dialog, call this code:<code>
   const dialogRef = this.dialog.open(AlertDialogComponent, {
     width: '250px',
     data: {message: "OK, Jahaa, sehr gut!"}
   });
</code>
  - Note: we use ''date.message'' to pass the message to our alert dialog component. Go back to step 3 and 4, you will see how to dialog get that ''date''.
{{ :ng:ng_alert_dialog.png?nolink&200 |}}

===== Dialog with Response =====
  - Do all the thing like the basic dialog
  - Modify the HTML of your component so that use can do some input, bind that input to a variable in your ts file. 
  - The ''component that open the dialog'' should subscribe the dialog afterClosed event as below. The ''result'' would be what the dialog component pass to the subscriber<code>
    dialogRef.afterClosed().subscribe(result => {...});</code>
  -  In the ''dialog component'', when you close it, close it with a parameter of any kind you like. that would be what the subscriber receives as the ''result'' variable. In the below case, the subscriber will receive a number of 10.<code>
this.dialogRef.close(10);</code>