com.vaadin.client.data.

java.lang.Object
- com.vaadin.client.data.AbstractRemoteDataSource<T>

Type Parameters:

T - the row type

All Implemented Interfaces:

DataSource<T>

Direct Known Subclasses:

RpcDataSourceConnector.RpcDataSource
```
public abstract class AbstractRemoteDataSource<T>
extends Object
implements DataSource<T>
```
Base implementation for data sources that fetch data from a remote system. This class takes care of caching data and communicating with the data source user. An implementation of this class should override requestRows(int, int, RequestRowsCallback) to trigger asynchronously loading of data and then pass the loaded data into the provided callback.

Since:

7.4

Author:

Vaadin Ltd

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`static class`	`AbstractRemoteDataSource.RequestRowsCallback<T>`	Callback used by `requestRows(int, int, RequestRowsCallback)` to pass data to the underlying implementation when data has been fetched.
`protected class`	`AbstractRemoteDataSource.RowHandleImpl`

Nested classes/interfaces inherited from interface com.vaadin.client.data.DataSource
DataSource.RowHandle<T>

Constructor Summary

Constructors
Constructor Description

AbstractRemoteDataSource()

Method Summary

All Methods
Modifier and Type	Method	Description
`protected boolean`	`canFetchData()`	Checks if it is possible to currently fetch data from the remote data source.
`void`	`ensureAvailability(int firstRowIndex, int numberOfRows)`	Informs the data source that data for the given range is needed.
`Range`	`getCachedRange()`	Gets the current range of cached rows
`DataSource.RowHandle<T>`	`getHandle(T row)`	Gets a `DataSource.RowHandle` of a row object in the cache.
`Range`	`getRequestedAvailability()`	Gets the row index range that was requested by the previous call to `ensureAvailability(int, int)`.
`T`	`getRow(int rowIndex)`	Retrieves the data for the row at the given index.
`abstract Object`	`getRowKey(T row)`	Gets a stable key for the row object.
`int`	`indexOf(T row)`	Retrieves the index for given row object.
`protected int`	`indexOfKey(Object rowKey)`
`protected void`	`insertRowData(int firstRowIndex, int count)`	Informs this data source that new data has been inserted from the server.
`protected boolean`	`isPinned(T row)`
`boolean`	`isWaitingForData()`	Checks whether this data source is currently waiting for more rows to become available.
`protected void`	`onDropFromCache(int rowIndex)`	Deprecated. replaced by `onDropFromCache(int, Object)`
`protected void`	`onDropFromCache(int rowIndex, T removed)`	A hook that can be overridden to do something whenever a row has been dropped from the cache.
`protected void`	`pinHandle(AbstractRemoteDataSource.RowHandleImpl handle)`	Pins a row with given handle.
`protected void`	`removeRowData(int firstRowIndex, int count)`	Informs this data source that the server has removed data.
`protected abstract void`	`requestRows(int firstRowIndex, int numberOfRows, AbstractRemoteDataSource.RequestRowsCallback<T> callback)`	Triggers fetching rows from the remote data source.
`protected void`	`resetDataAndSize(int newSize)`	Updates the size, discarding all cached data.
`void`	`setCacheStrategy(CacheStrategy cacheStrategy)`	Sets the cache strategy that is used to determine how much data is fetched and cached.
`void`	`setDataChangeHandler(DataChangeHandler dataChangeHandler)`	Sets a data change handler to inform when data is updated, added or removed.
`protected void`	`setRowData(int firstRowIndex, List<T> rowData)`	Informs this data source that updated data has been sent from the server.
`int`	`size()`	Returns the number of rows in the data source.
`protected void`	`unpinHandle(AbstractRemoteDataSource.RowHandleImpl handle)`	Unpins a previously pinned row with given handle.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - AbstractRemoteDataSource
```
public AbstractRemoteDataSource()
```
- Method Detail
  - pinHandle
```
protected void pinHandle(AbstractRemoteDataSource.RowHandleImpl handle)
```
    Pins a row with given handle. This function can be overridden to do specific logic related to pinning rows.
    
    Parameters:
    
    handle - row handle to pin
  - unpinHandle
```
protected void unpinHandle(AbstractRemoteDataSource.RowHandleImpl handle)
                    throws IllegalStateException
```
    Unpins a previously pinned row with given handle. This function can be overridden to do specific logic related to unpinning rows.
    
    Parameters:
    
    handle - row handle to unpin
    
    Throws:
    
    IllegalStateException - if given row handle has not been pinned before
  - ensureAvailability
```
public void ensureAvailability(int firstRowIndex,
                               int numberOfRows)
```
    Description copied from interface: DataSource
    
    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 DataSource.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.
    
    Specified by:
    
    ensureAvailability in interface DataSource<T>
    
    Parameters:
    
    firstRowIndex - the index of the first needed row
    
    numberOfRows - the number of needed rows
  - getRequestedAvailability
```
public Range getRequestedAvailability()
```
    Gets the row index range that was requested by the previous call to ensureAvailability(int, int).
    
    Returns:
    
    the requested availability range
  - isWaitingForData
```
public boolean isWaitingForData()
```
    Checks whether this data source is currently waiting for more rows to become available.
    
    Specified by:
    
    isWaitingForData in interface DataSource<T>
    
    Returns:
    
    true if waiting for data; otherwise false
  - onDropFromCache
```
@Deprecated
protected void onDropFromCache(int rowIndex)
```
    Deprecated.
    replaced by onDropFromCache(int, Object)
    
    A hook that can be overridden to do something whenever a row has been dropped from the cache. DataSource no longer has anything in the given index.
    NOTE: This method has been replaced. Override onDropFromCache(int, Object) instead of this method.
    
    Parameters:
    
    rowIndex - the index of the dropped row
    
    Since:
    
    7.5.0
  - onDropFromCache
```
protected void onDropFromCache(int rowIndex,
                               T removed)
```
    A hook that can be overridden to do something whenever a row has been dropped from the cache. DataSource no longer has anything in the given index.
    
    Parameters:
    
    rowIndex - the index of the dropped row
    
    removed - the removed row object
    
    Since:
    
    7.6
  - requestRows
```
protected abstract void requestRows(int firstRowIndex,
                                    int numberOfRows,
                                    AbstractRemoteDataSource.RequestRowsCallback<T> callback)
```
    Triggers fetching rows from the remote data source. The provided callback should be informed when the requested rows have been received.
    
    Parameters:
    
    firstRowIndex - the index of the first row to fetch
    
    numberOfRows - the number of rows to fetch
    
    callback - callback to inform when the requested rows are available
  - getRow
```
public T getRow(int rowIndex)
```
    Description copied from interface: DataSource
    
    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. DataSource.ensureAvailability(int, int) should be used to signal what data will be needed.
    
    Specified by:
    
    getRow in interface DataSource<T>
    
    Parameters:
    
    rowIndex - the index of the row to retrieve data for
    
    Returns:
    
    data for the row; or null if no data is available
  - indexOf
```
public int indexOf(T row)
```
    Retrieves the index for given row object.
    Note: This method does not verify that the given row object exists at all in this DataSource.
    
    Parameters:
    
    row - the row object
    
    Returns:
    
    index of the row; or -1 if row is not available
  - setDataChangeHandler
```
public void setDataChangeHandler(DataChangeHandler dataChangeHandler)
```
    Description copied from interface: DataSource
    
    Sets a data change handler to inform when data is updated, added or removed.
    
    Specified by:
    
    setDataChangeHandler in interface DataSource<T>
    
    Parameters:
    
    dataChangeHandler - the data change handler
  - setRowData
```
protected void setRowData(int firstRowIndex,
                          List<T> rowData)
```
    Informs this data source that updated data has been sent from the server.
    
    Parameters:
    
    firstRowIndex - the index of the first received row
    
    rowData - a list of rows, starting from firstRowIndex
  - removeRowData
```
protected void removeRowData(int firstRowIndex,
                             int count)
```
    Informs this data source that the server has removed data.
    
    Parameters:
    
    firstRowIndex - the index of the first removed row
    
    count - the number of removed rows, starting from firstRowIndex
  - insertRowData
```
protected void insertRowData(int firstRowIndex,
                             int count)
```
    Informs this data source that new data has been inserted from the server.
    
    Parameters:
    
    firstRowIndex - the destination index of the new row data
    
    count - the number of rows inserted
  - getCachedRange
```
public Range getCachedRange()
```
    Gets the current range of cached rows
    
    Returns:
    
    the range of currently cached rows
  - setCacheStrategy
```
public void setCacheStrategy(CacheStrategy cacheStrategy)
```
    Sets the cache strategy that is used to determine how much data is fetched and cached.
    The new strategy is immediately used to evaluate whether currently cached rows should be discarded or new rows should be fetched.
    
    Parameters:
    
    cacheStrategy - a cache strategy implementation, not null
  - getHandle
```
public DataSource.RowHandle<T> getHandle(T row)
                                  throws IllegalStateException
```
    Description copied from interface: DataSource
    
    Gets a DataSource.RowHandle of a row object in the cache.
    
    Specified by:
    
    getHandle in interface DataSource<T>
    
    Parameters:
    
    row - the row object for which to retrieve a row handle
    
    Returns:
    
    a non-null row handle of the given row object
    
    Throws:
    
    IllegalStateException
  - getRowKey
```
public abstract Object getRowKey(T row)
```
    Gets a stable key for the row object.
    This method is a workaround for the fact that there is no means to force proper implementations for Object.hashCode() and Object.equals(Object) methods.
    Since the same row object will be created several times for the same logical data, the DataSource needs a mechanism to be able to compare two objects, and figure out whether or not they represent the same data. Even if all the fields of an entity would be changed, it still could represent the very same thing (say, a person changes all of her names.)
    A very usual and simple example what this could be, is an unique ID for this object that would also be stored in a database.
    
    Parameters:
    
    row - the row object for which to get the key
    
    Returns:
    
    a non-null object that uniquely and consistently represents the row object
  - size
```
public int size()
```
    Description copied from interface: DataSource
    
    Returns the number of rows in the data source.
    
    Specified by:
    
    size in interface DataSource<T>
    
    Returns:
    
    the current size of the data source
  - resetDataAndSize
```
protected void resetDataAndSize(int newSize)
```
    Updates the size, discarding all cached data. This method is used when the size of the container is changed without any information about the structure of the change. In this case, all cached data is discarded to avoid cache offset issues.
    If you have information about the structure of the change, use insertRowData(int, int) or removeRowData(int, int) to indicate where the inserted or removed rows are located.
    
    Parameters:
    
    newSize - the new size of the container
  - indexOfKey
```
protected int indexOfKey(Object rowKey)
```
  - isPinned
```
protected boolean isPinned(T row)
```
  - canFetchData
```
protected boolean canFetchData()
```
    Checks if it is possible to currently fetch data from the remote data source.
    
    Returns:
    
    true if it is ok to try to fetch data, false if it is known that fetching data will fail and should not be tried right now.
    
    Since:
    
    7.7.2

com.vaadin.client.data.

Class AbstractRemoteDataSource<T>

Nested Class Summary

Nested classes/interfaces inherited from interface com.vaadin.client.data.DataSource

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

AbstractRemoteDataSource

Method Detail

pinHandle

unpinHandle

ensureAvailability

getRequestedAvailability

isWaitingForData

onDropFromCache

onDropFromCache

requestRows

getRow

indexOf

setDataChangeHandler

setRowData

removeRowData

insertRowData

getCachedRange

setCacheStrategy

getHandle

getRowKey

size

resetDataAndSize

indexOfKey

isPinned

canFetchData