Monthly Archives: January 2021

How to prevent updates of a SQL column using JPA ?

When working with JPA / Hibernate, you may want to prevent updates of a given column. This is typically the case with your primary key. This is possible using the “updatable” attribute of the @Column annotation. Ex :

    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", updatable = false, nullable = false)
    private Long id;

How to create an Angular 7+ component with two way binding ?

You have an angular component, and would like to have a value with a two way binding similar to ngModel. The easiest way is to :

  • add an Input on your document
  • add an Ouput whose name is the one of the input, suffixed by Change (that’s a required naming convention)

For example :

  selector: 'app-select-nature-document',
  template: './select-nature-document.component.html',
  styleUrls: ['./select-nature-document.component.css']
export class SelectNatureDocumentComponent implements OnInit {
  natureDocument: NatureDocument;
  natureDocumentChange: EventEmitter<NatureDocument> = new EventEmitter<NatureDocument>();

You can then notify the value change using the output event emitter :

  onNatureDocumentSelected() {

And the component can be used like this :

<app-select-nature-document [(natureDocument)]="editedDocument.nature"></app-select-nature-document>

Thanks to