com.vaadin.flow.data.provider

Interface HasLazyDataView<T,F,V extends LazyDataView<T>>

Type Parameters:

T - item type

F - filter type

V - DataView type

All Superinterfaces:

Serializable

All Known Implementing Classes:

ComboBox, CrudGrid, Grid, GridPro, TreeGrid

public interface HasLazyDataView<T,F,V extends LazyDataView<T>>
extends Serializable

Interface that defines methods for fetching items lazily from a backend. The API will return a LazyDataView.

Since:

Method Summary

Modifier and Type	Method and Description
V	getLazyDataView() Get the LazyDataView for the component that allows access to the items in the component.
V	setItems(BackEndDataProvider<T,F> dataProvider) Supply items with a BackEndDataProvider that lazy loads items from a backend.
default V	setItems(CallbackDataProvider.FetchCallback<T,F> fetchCallback) Supply items lazily with a callback from a backend.
default V	setItems(CallbackDataProvider.FetchCallback<T,F> fetchCallback, CallbackDataProvider.CountCallback<T,F> countCallback) Supply items lazily with callbacks: the first one fetches the items based on offset, limit and an optional filter, the second provides the exact count of items in the backend.

Method Detail

setItems

default V setItems(CallbackDataProvider.FetchCallback<T,F> fetchCallback)

Supply items lazily with a callback from a backend. The component will automatically fetch more items and adjust its size until the backend runs out of items. Usage example without component provided filter:

component.setItems(query -> orderService.getOrders(query.getOffset(), query.getLimit());

If the component supports filtering, it can be fetched with query.getFilter().

The returned data view object can be used for further configuration, or later on fetched with getLazyDataView(). For using in-memory data, like Collection, use HasListDataView.setItems(Collection) instead.

Parameters:

fetchCallback - function that returns a stream of items from the backend based on the offset, limit and an optional filter provided by the query object

Returns:

LazyDataView instance for further configuration

setItems

default V setItems(CallbackDataProvider.FetchCallback<T,F> fetchCallback,
                   CallbackDataProvider.CountCallback<T,F> countCallback)

Supply items lazily with callbacks: the first one fetches the items based on offset, limit and an optional filter, the second provides the exact count of items in the backend. Use this in case getting the count is cheap and the user benefits from the component showing immediately the exact size. Usage example without component provided filter:

component.setItems( query -> orderService.getOrders(query.getOffset, query.getLimit()), query -> orderService.getSize());

If the component supports filtering, it can be fetched with query.getFilter().

The returned data view object can be used for further configuration, or later on fetched with getLazyDataView(). For using in-memory data, like Collection, use HasListDataView.setItems(Collection) instead.

Parameters:

fetchCallback - function that returns a stream of items from the back end for a query

countCallback - function that return the number of items in the back end for a query

Returns:

LazyDataView instance for further configuration

setItems

V setItems(BackEndDataProvider<T,F> dataProvider)

Supply items with a BackEndDataProvider that lazy loads items from a backend. Note that component will query the data provider for the item count. In case that is not desired for performance reasons, use setItems(CallbackDataProvider.FetchCallback) instead.

The returned data view object can be used for further configuration, or later on fetched with getLazyDataView(). For using in-memory data, like Collection, use HasListDataView.setItems(Collection) instead.

Parameters:

dataProvider - BackEndDataProvider instance

Returns:

LazyDataView instance for further configuration

getLazyDataView

V getLazyDataView()

Get the LazyDataView for the component that allows access to the items in the component. Throws an exception if the items are not provided lazily and another data view type should be used, like ListDataView.

Returns:

LazyDataView instance

Throws:

IllegalStateException - when lazy data view is not applicable