Vaadin Spring Boot #autowired field returns null in a view - spring-boot

Question

First off, please excuse my question due to my being new to spring boot ecosystem. In my application, I've a vaadin page, where I want to submit user details to DB, using repository. In my view class, I've added them as #autowired fields, however, during the runtime, I see that their values are run so the operation fails. I know that to benefit from #autowired, the instances should not be created newly during constructing but I couldn't figure out how I should do it on my own. Here are my classes:
#SuppressWarnings("serial")
public class LoginAwareComposite extends Composite<Div> {
#Autowired
private ApplicationEventPublisher publisher;
public LoginAwareComposite() {
}
#Override
protected void onAttach(AttachEvent event) {
super.onAttach(event);
UserCredentials userPrincipal = UI.getCurrent().getSession().getAttribute(UserCredentials.class);
if (userPrincipal != null) {
// --- NOT LOGGED IN
UI.getCurrent().navigate(AddressBookManagementView.class);
}
}
}
#SuppressWarnings("serial")
#Route(value = "account")
#Theme(value = Lumo.class, variant = Lumo.LIGHT)
public class AddressBookManagementView extends LoginAwareComposite {
private VerticalLayout pageLayout = new VerticalLayout();
public AddressBookManagementView() {
getContent().setSizeFull();
getContent().add(initPage());
}
private Component initPage() {
pageLayout.getStyle().set("padding-left", "0px");
pageLayout.getStyle().set("padding-bottom", "0px");
pageLayout.getStyle().set("padding-right", "0px");
pageLayout.getStyle().set("overflow", "auto");
pageLayout.setSizeFull();
pageLayout.add(new HeaderLayout(), new BodyLayout(), new FooterLayout());
return pageLayout;
}
}
#SuppressWarnings("serial")
#SpringComponent
public class BodyLayout extends VerticalLayout {
// some fields
#Autowired
EmailRepository emailRepository;
#Autowired
FaxRepository faxRepository;
public BodyLayout() {
init(); //this function inits the view, and eventually inits the on click event for submit button , which then calls my function
}
private void myFunction() {
//here i use the repository entities but they do return null although they are autowired
}
So what happens is, in BodyLayout's constructor we call init() function which is used to init the layout and give functionality buttons etc, one of subfunctions inside the init method gives functionality to submit button using myFunction. MyFuction uses the repository entity but it returns null.

Answer 1

Since you are using springboot with vaadin ensure the following :
Make sure that the #Repository annotation is used on your repository interfaces like on EmailRepository.
Try using constructor injection for your repository classes like :
Try like below :
#SuppressWarnings("serial")
#SpringComponent
#UIScope
public class BodyLayout extends VerticalLayout {
// some fields
private final EmailRepository emailRepository;
private final FaxRepository faxRepository;
#Autowired
public BodyLayout(EmailRepository emailRepository, FaxRepository faxRepository) {
this.emailRepository = emailRepository;
this.faxRepository = faxRepository;
init(); //this function inits the view, and eventually inits the on click event for submit button , which then calls my function
}
private void myFunction() {
//here i use the repository entities but they do return null although they are autowired
}

Answer 2

I was able to get it working as follows:
#SuppressWarnings("serial")
#Route(value = "account")
#Theme(value = Lumo.class, variant = Lumo.LIGHT)
#UIScope
#SpringComponent
public class AddressBookManagementView extends LoginAwareComposite {
private VerticalLayout pageLayout = new VerticalLayout();
#Autowired
BodyLayout bodyLayout;
public AddressBookManagementView(BodyLayout bodyLayout) {
this.bodyLayout = bodyLayout;
getContent().setSizeFull();
getContent().add(initPage());
}
private Component initPage() {
pageLayout.getStyle().set("padding-left", "0px");
pageLayout.getStyle().set("padding-bottom", "0px");
pageLayout.getStyle().set("padding-right", "0px");
pageLayout.getStyle().set("overflow", "auto");
pageLayout.setSizeFull();
pageLayout.add(new HeaderLayout(), bodyLayout, new FooterLayout());
return pageLayout;
}
Then BodyLayout is
#SuppressWarnings("serial")
#UIScope
#SpringComponent
public class BodyLayout extends VerticalLayout {
private final EmailRepository emailRepository;
private final FaxRepository faxRepository;
#Autowired
public BodyLayout(EmailRepository emailRepository, FaxRepository faxRepository) {
this.emailRepository = emailRepository;
this.faxRepository = faxRepository;
init();
}

Answer 3

Roughly only #Route, layouts, and the vaadin init listener takes part in automatic dependency injection (that is: the vaadin spring integration asks the spring context to build them). If you do new MyClass() it never takes part in DI. Using field based injection with #Autowired hides this problem - so using constructor based injection is the "industry standard". The other way around is to not build your own instances, if you want to take part in DI but ask the spring context to build an instance for you.