Package com.vaadin.client.data

Interface DataSource<T>

  • Type Parameters:
    T - the row type
    All Known Implementing Classes:
    AbstractRemoteDataSource, ListDataSource, RpcDataSourceConnector.RpcDataSource
    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

    • 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 setDataChangeHandler(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

      • setDataChangeHandler

        void setDataChangeHandler​(DataChangeHandler dataChangeHandler)
        Sets a data change handler to inform when data is updated, added or removed.
        Parameters:
        dataChangeHandler - the data change 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