com.vaadin.client.data

Interface DataSource<T>

Type Parameters:

T - the row type

All Known Implementing Classes:

AbstractRemoteDataSource, DataCommunicatorConnector.VaadinDataSource, ListDataSource

public interface DataSource<T>

Source of data for widgets showing lazily loaded data based on indexable items (e.g. rows) of a specified type. The data source is a lazy view into a larger data set.

Since:

7.4

Author:

Vaadin Ltd

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	DataSource.RowHandle<T> A handle that contains information on whether a row should be pinned or unpinned, and also always the most recent representation for that particular row.

Method Summary

Modifier and Type	Method and Description
default Registration	addDataChangeHandler(Consumer<Range> refreshMethod) Sets a simple data change handler for a widget without lazy loading.
Registration	addDataChangeHandler(DataChangeHandler dataChangeHandler) Sets a data change handler to inform when data is updated, added or removed.
void	ensureAvailability(int firstRowIndex, int numberOfRows) Informs the data source that data for the given range is needed.
DataSource.RowHandle<T>	getHandle(T row) Gets a DataSource.RowHandle of a row object in the cache.
T	getRow(int rowIndex) Retrieves the data for the row at the given index.
boolean	isWaitingForData() Checks whether this data source is currently waiting for more rows to become available.
int	size() Returns the number of rows in the data source.

Method Detail

ensureAvailability

void ensureAvailability(int firstRowIndex,
                        int numberOfRows)

Informs the data source that data for the given range is needed. A data source only has one active region at a time, so calling this method discards the previously set range.

This method triggers lazy loading of data if necessary. The change handler registered using addDataChangeHandler(DataChangeHandler) is informed when new data has been loaded.

After any possible lazy loading and updates are done, the change handler is informed that new data is available.

Parameters:

firstRowIndex - the index of the first needed row

numberOfRows - the number of needed rows

getRow

T getRow(int rowIndex)

Retrieves the data for the row at the given index. If the row data is not available, returns null.

This method does not trigger loading of unavailable data. ensureAvailability(int, int) should be used to signal what data will be needed.

Parameters:

rowIndex - the index of the row to retrieve data for

Returns:

data for the row; or null if no data is available

size

int size()

Returns the number of rows in the data source.

Returns:

the current size of the data source

addDataChangeHandler

Registration addDataChangeHandler(DataChangeHandler dataChangeHandler)

Sets a data change handler to inform when data is updated, added or removed.

Parameters:

dataChangeHandler - the data change handler

Returns:

registration for removing the handler

addDataChangeHandler

default Registration addDataChangeHandler(Consumer<Range> refreshMethod)

Sets a simple data change handler for a widget without lazy loading. Refresh method should reset all the data in the widget.

Parameters:

refreshMethod - a method to refresh all data in the widget

Returns:

registration for removing the handler

getHandle

DataSource.RowHandle<T> getHandle(T row)

Gets a DataSource.RowHandle of a row object in the cache.

Parameters:

row - the row object for which to retrieve a row handle

Returns:

a non-null row handle of the given row object

isWaitingForData

boolean isWaitingForData()

Checks whether this data source is currently waiting for more rows to become available.

Returns:

true if waiting for data; otherwise false

Since:

7.7.2