com.vaadin.flow.data.provider

Interface DataView<T>

Type Parameters:

T - data type

All Superinterfaces:

Serializable

All Known Subinterfaces:

LazyDataView<T>, ListDataView<T,V>

All Known Implementing Classes:

AbstractDataView, AbstractLazyDataView, AbstractListDataView, CheckboxGroupDataView, CheckboxGroupListDataView, GridDataView, GridLazyDataView, GridListDataView, SelectDataView, SelectListDataView

public interface DataView<T>
extends Serializable

Base view interface for getting information on current data set of a Component.

Since:

Method Summary

Modifier and Type	Method and Description
Registration	addItemCountChangeListener(ComponentEventListener<ItemCountChangeEvent<?>> listener) Add an item count change listener that is fired when the item count changes.
T	getItem(int index) Gets the item at the given index from the data available to the component.
Stream<T>	getItems() Get the full data available to the component.
void	refreshItem(T item) Notifies the component that the item has been updated and thus should be refreshed.
void	setIdentifierProvider(IdentifierProvider<T> identifierProvider) Sets an identifier provider, which returns an identifier for the given item.

Method Detail

getItem

T getItem(int index)

Gets the item at the given index from the data available to the component. Data is filtered and sorted the same way as in the component.

Parameters:

index - item index number

Returns:

item on index

Throws:

IndexOutOfBoundsException - requested index is outside of the filtered and sorted data set

getItems

Stream<T> getItems()

Get the full data available to the component. Data is filtered and sorted the same way as in the component.

Returns:

filtered and sorted data set

refreshItem

void refreshItem(T item)

Notifies the component that the item has been updated and thus should be refreshed.

For this to work properly, the item must either implement Object.equals(Object) and Object.hashCode() to consider both the old and the new item instances to be equal, or alternatively use the setIdentifierProvider(IdentifierProvider) to set an appropriate item's identifier.

This method delegates the update to DataProvider.refreshItem(Object).

Parameters:

item - item containing updated state

See Also:

setIdentifierProvider(IdentifierProvider)

addItemCountChangeListener

Registration addItemCountChangeListener(ComponentEventListener<ItemCountChangeEvent<?>> listener)

Add an item count change listener that is fired when the item count changes. This can happen for instance when filtering the items.

Item count change listener is bound to the component and will be retained even if the data changes by setting of a new items or DataProvider to component.

NOTE: when the component supports lazy loading (implements HasLazyDataView) and a count callback has not been provided, an estimate of the item count is used and increased until the actual count has been reached. When the estimate is used, the event is fired with the ItemCountChangeEvent.isItemCountEstimated() returning true.

Parameters:

listener - item count change listener to register

Returns:

registration for removing the listener

setIdentifierProvider

void setIdentifierProvider(IdentifierProvider<T> identifierProvider)

Sets an identifier provider, which returns an identifier for the given item. The identifier is used for comparing the equality of items. Usage example: dataView.setIdentifiedProvider(Item::getId);.

Parameters:

identifierProvider - function that returns the non-null identifier for a given item