Vaadin 14 - grid disappearing when using nested layout

问题

After implementing nested layouts i faced the problem with rendering component containing grid. The analysis shows that is present in html but it has display-block attributes and the grid is never visible.

I read the similar question (Vaadin 14 - Grid not Displaying/Populating When Used in Nested Layout) but the suggestions listed there brought me no result.

Here comes my code:

MainLayout.kt:

@Theme(value = Material::class, variant = Material.DARK)
class MainLayout : Composite<Div>(), RouterLayout {

    //Component to delegate content through.
    private val mainContent: Div = Div()
    private val layout = VerticalLayout(
            Span("from MainLayout top"),
            mainContent,
            Span("from MainLayout bottom"))


    override fun showRouterLayoutContent(hasElement: HasElement) {

        Objects.requireNonNull(hasElement)
        Objects.requireNonNull(hasElement.element)
        mainContent.removeAll()
        mainContent.element.appendChild(hasElement.element)
    }

    init {
        content.add(layout)
    }
}

LayoutWithMenuBar.kt:

@ParentLayout(value = MainLayout::class)
class LayoutWithMenuBar : Composite<Div>(), RouterLayout {

    private val mainContent: Div = Div()

    private val menuBar = HorizontalLayout(
            RouterLink("Home", MainView::class.java),
            RouterLink("Tprojects", TProjectDashboard::class.java),
            RouterLink("ViewA", ViewA::class.java),
            RouterLink("ViewB", ViewB::class.java))


    private val root = VerticalLayout(menuBar, mainContent)

    override fun showRouterLayoutContent(hasElement: HasElement) {

        Objects.requireNonNull(hasElement)
        Objects.requireNonNull(hasElement.element)
        mainContent.removeAll()
        mainContent.element.appendChild(hasElement.element)
    }


    init {

        content.add(root)
    }
}

and a component containing grid - TProjectDashboard:

@Route("dashboard/tproject", layout = LayoutWithMenuBar::class)
class TProjectDashboard(@Autowired val tprojectService: TProjectService): VerticalLayout() {

    var tprojectGrid = Grid<TProject>(TProject::class.java)

    init {
        //tprojectGrid
        tprojectGrid.setColumns(
                TProject::tprojectUuid.name,
                TProject::tprojectClass.name,
                TProject::tprojectState.name,
                TProject::tentityState.name,
                TProject::size.name)

        tprojectGrid.setItems(tprojectService.findAll())

        tprojectGrid.setSizeFull()
        tprojectGrid.setWidthFull()
        tprojectGrid.setHeightFull()

        add(tprojectGrid)

        setSizeFull()
        setHeightFull()
        setWidthFull()
    }
}

The same result i have when changing TProjectDashboard parent from VerticalLayout to Composite. The nested layouts approach works well for simple components like Span and if i remove layout reference from @Route annotation i will see my grid.

Here is the screen how it looks like now: enter image description here

Would appreciate for any hints or solutions.

Thanks in advance.

回答1:

It's probably a sizing issue that unfortunately happens too often. I would start with calling setSizeFull() on the mainContent div. If that doesn't help, go through the elements in the browser devtools and try to see where the size disappears, e.g. what is the first element that has 0 width or height.

Edit: Setting setSizeFull() on all components works. I would simplify your layouts slightly, though, by changing the composites to be of type VerticalLayout. Then you can get rid of a lot of the setSizeFull() calls.

The code below is in Java as I don't have Kotlin set up, you can call getContent().setSizeFull() in MainLayout if you want it to take the full height of the page.

MainLayout

@Theme(value = Material.class, variant = Material.DARK)
public class MainLayout extends Composite<VerticalLayout> implements RouterLayout {

    //Component to delegate content through.
    private Div mainContent = new Div();

    public MainLayout() {
        getContent().add(
                new Span("from MainLayout top"),
                mainContent,
                new Span("from MainLayout bottom"));
        mainContent.setSizeFull();
    }

    @Override
    public void showRouterLayoutContent(HasElement hasElement) {
        Objects.requireNonNull(hasElement);
        Objects.requireNonNull(hasElement.getElement());
        mainContent.removeAll();
        mainContent.getElement().appendChild(hasElement.getElement());
    }
}

LayoutWithMenuBar

@ParentLayout(value = MainLayout.class)
public class LayoutWithMenuBar extends Composite<VerticalLayout> implements RouterLayout {

    private Div mainContent = new Div();

    private HorizontalLayout menuBar = new HorizontalLayout(
            new RouterLink("Tprojects", TProjectDashboard.class));

    public LayoutWithMenuBar() {
        getContent().add(menuBar, mainContent);
        mainContent.setSizeFull();
    }

    @Override
    public void showRouterLayoutContent(HasElement hasElement) {
        Objects.requireNonNull(hasElement);
        Objects.requireNonNull(hasElement.getElement());
        mainContent.removeAll();
        mainContent.getElement().appendChild(hasElement.getElement());
    }
}

TProjectDashboard

@Route(value = "dashboard/tproject", layout = LayoutWithMenuBar.class)
public class TProjectDashboard extends VerticalLayout {

    private Grid<TProject> tprojectGrid = new Grid<>(TProject.class);

    public TProjectDashboard() {

        tprojectGrid.setItems(
                new TProject("Erik", "Software Engineer"),
                new TProject("Fia", "Kindergarden teacher"),
                new TProject("Jack", "All trades")
        );

        add(tprojectGrid);
    }
}

来源：https://stackoverflow.com/questions/60100058/vaadin-14-grid-disappearing-when-using-nested-layout