com.vaadin.flow.data.provider

Class DataCommunicator<T>

java.lang.Object

com.vaadin.flow.data.provider.DataCommunicator<T>

Type Parameters:

T - the bean type

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

HierarchicalDataCommunicator, PagelessDataCommunicator

public class DataCommunicator<T>
extends Object
implements Serializable

DataProvider base class. This class is the base for all DataProvider communication implementations. It uses data generators (BiFunctions) to write JsonObjects representing each data object to be sent to the client-side.

Since:

1.0

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_PAGE_INCREASE_COUNT

Constructor Summary

Constructors

Constructor and Description
DataCommunicator(DataGenerator<T> dataGenerator, ArrayUpdater arrayUpdater, SerializableConsumer<elemental.json.JsonArray> dataUpdater, StateNode stateNode) Creates a new instance.

Method Summary

Modifier and Type	Method and Description
Query	buildQuery(int offset, int limit) Generate a data query with component sorting and filtering.
void	confirmUpdate(int updateId) Confirm update with the given updateId.
protected Stream<T>	fetchFromProvider(int offset, int limit) Fetches a list of items from the DataProvider.
List<QuerySortOrder>	getBackEndSorting() Returns the QuerySortOrder to use with backend sorting.
DataProvider<T,?>	getDataProvider() Gets the current data provider from this DataCommunicator.
protected int	getDataProviderSize() Getter method for determining the item count of the data.
protected Object	getFilter() Get the object used for filtering in this data communicator.
SerializableComparator<T>	getInMemorySorting() Returns the Comparator to use with in-memory sorting.
T	getItem(int index) Gets the item at the given index from the data available to the component.
int	getItemCount() This is the latest DataProvider item count informed to the client or fetched from the DataProvider if client data has not been sent.
int	getItemCountEstimate() Gets the item count estimate used.
int	getItemCountEstimateIncrease() Gets the item count estimate increase used.
DataKeyMapper<T>	getKeyMapper() Gets the DataKeyMapper used by this DataCommunicator.
int	getPageSize() Returns the page size set to fetch items.
protected void	handleDataRefreshEvent(DataChangeEvent.DataRefreshEvent<T> event)
boolean	isDefinedSize() Returns whether defined or undefined size is used.
boolean	isItemActive(T item) Returns whether the given item is part of the active items.
boolean	isPagingEnabled() Returns whether paged queries are enabled or not.
void	refresh(T data) Informs the DataCommunicator that a data object has been updated.
void	reset() Resets all the data.
void	setBackEndSorting(List<QuerySortOrder> sortOrder) Sets the QuerySortOrders to use with backend sorting.
void	setCountCallback(CallbackDataProvider.CountCallback<T,?> countCallback) Sets the size callback to be used and switches the component to exact row count.
<F> SerializableConsumer<F>	setDataProvider(DataProvider<T,F> dataProvider, F initialFilter) Sets the current data provider for this DataCommunicator.
void	setDefinedSize(boolean definedSize) Changes between defined and undefined size and clears any previously set count callback.
void	setInMemorySorting(SerializableComparator<T> comparator) Sets the Comparator to use with in-memory sorting.
void	setItemCountEstimate(int itemCountEstimate) Sets the item count estimate to use and switches component to undefined size.
void	setItemCountEstimateIncrease(int itemCountEstimateIncrease) Sets the item count estimate increase to use and switches the component to undefined size if not yet used.
protected void	setKeyMapper(DataKeyMapper<T> keyMapper) Sets the DataKeyMapper used in this DataCommunicator.
void	setPageSize(int pageSize) Sets the page size that is used to fetch items.
void	setPagingEnabled(boolean pagingEnabled) Sets whether paged queries or offset/limit queries will be used.
void	setRequestedRange(int start, int length) Sets the requested range of data to be sent.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_PAGE_INCREASE_COUNT

public static final int DEFAULT_PAGE_INCREASE_COUNT

See Also:

Constant Field Values

Constructor Detail

DataCommunicator

public DataCommunicator(DataGenerator<T> dataGenerator,
                        ArrayUpdater arrayUpdater,
                        SerializableConsumer<elemental.json.JsonArray> dataUpdater,
                        StateNode stateNode)

Creates a new instance.

Parameters:

dataGenerator - the data generator function

arrayUpdater - array updater strategy

dataUpdater - data updater strategy

stateNode - the state node used to communicate for

Method Detail

setRequestedRange

public void setRequestedRange(int start,
                              int length)

Sets the requested range of data to be sent.

Parameters:

start - the start of the requested range

length - the end of the requested range

reset

public void reset()

Resets all the data.

It effectively resends all available data.

refresh

public void refresh(T data)

Informs the DataCommunicator that a data object has been updated.

Parameters:

data - updated data object; not null

confirmUpdate

public void confirmUpdate(int updateId)

Confirm update with the given updateId.

Parameters:

updateId - the update identifier

getDataProvider

public DataProvider<T,?> getDataProvider()

Gets the current data provider from this DataCommunicator.

Returns:

the data provider

setDataProvider

public <F> SerializableConsumer<F> setDataProvider(DataProvider<T,F> dataProvider,
                                                   F initialFilter)

Sets the current data provider for this DataCommunicator.

The returned consumer can be used to set some other filter value that should be included in queries sent to the data provider. It is only valid until another data provider is set.

This method also sets the data communicator to defined size - meaning that the given data provider is queried for size and previous size estimates are discarded.

Type Parameters:

F - the filter type

Parameters:

dataProvider - the data provider to set, not null

initialFilter - the initial filter value to use, or null to not use any initial filter value

Returns:

a consumer that accepts a new filter value to use

getItemCount

public int getItemCount()

This is the latest DataProvider item count informed to the client or fetched from the DataProvider if client data has not been sent.

Returns:

count of available items

isItemActive

public boolean isItemActive(T item)

Returns whether the given item is part of the active items.

Parameters:

item - the item to check, not null

Returns:

true if item is active, false if not

getItem

public 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.

Call to the backend is triggered if the item for a requested index is not present in the cached active items.

Parameters:

index - the index of the item to get

Returns:

item on index

Throws:

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

buildQuery

public Query buildQuery(int offset,
                        int limit)

Generate a data query with component sorting and filtering.

Parameters:

offset - first index to fetch

limit - fetched item count

Returns:

Query for component state

setPageSize

public void setPageSize(int pageSize)

Sets the page size that is used to fetch items. The queries to data provider are a multiple of the page size.

Parameters:

pageSize - the page size to set

getPageSize

public int getPageSize()

Returns the page size set to fetch items.

Returns:

the page size

setCountCallback

public void setCountCallback(CallbackDataProvider.CountCallback<T,?> countCallback)

Sets the size callback to be used and switches the component to exact row count. The new count will be used after this roundtrip.

Parameters:

countCallback - the size callback to use

setItemCountEstimate

public void setItemCountEstimate(int itemCountEstimate)

Sets the item count estimate to use and switches component to undefined size. Any previously set count callback is cleared. The new estimate is applied if the actual count has not been discovered and if the estimate is greater than the number of requested items. Otherwise it is not applied until there has been a reset.

NOTE: setting item count estimate that is less than two pages (set with setPageSize(int)) can cause extra requests initially or after a reset.

Parameters:

itemCountEstimate - the item count estimate to be used

getItemCountEstimate

public int getItemCountEstimate()

Gets the item count estimate used.

Returns:

the item count estimate used

setItemCountEstimateIncrease

public void setItemCountEstimateIncrease(int itemCountEstimateIncrease)

Sets the item count estimate increase to use and switches the component to undefined size if not yet used. Any previously set count callback is cleared. The step is used the next time that the count is adjusted. NOTE: the increase should be greater than the setPageSize(int) or it may cause bad performance.

Parameters:

itemCountEstimateIncrease - the item count estimate step to use

getItemCountEstimateIncrease

public int getItemCountEstimateIncrease()

Gets the item count estimate increase used.

Returns:

the item count estimate increase

setDefinedSize

public void setDefinedSize(boolean definedSize)

Changes between defined and undefined size and clears any previously set count callback. Calling with value true will use the DataProvider.size(Query) for getting the size. Calling with false will use whatever has been set with setItemCountEstimate(int) and increase the count when needed with setItemCountEstimateIncrease(int).

Parameters:

definedSize - true for defined size, false for undefined size

isDefinedSize

public boolean isDefinedSize()

Returns whether defined or undefined size is used.

Returns:

true for defined size, false for undefined size

getKeyMapper

public DataKeyMapper<T> getKeyMapper()

Gets the DataKeyMapper used by this DataCommunicator. Key mapper can be used to map keys sent to the client-side back to their respective data objects.

Returns:

key mapper

setKeyMapper

protected void setKeyMapper(DataKeyMapper<T> keyMapper)

Sets the DataKeyMapper used in this DataCommunicator. Key mapper can be used to map keys sent to the client-side back to their respective data objects.

Parameters:

keyMapper - the keyMapper

setInMemorySorting

public void setInMemorySorting(SerializableComparator<T> comparator)

Sets the Comparator to use with in-memory sorting.

Parameters:

comparator - comparator used to sort data

getInMemorySorting

public SerializableComparator<T> getInMemorySorting()

Returns the Comparator to use with in-memory sorting.

Returns:

comparator used to sort data

setBackEndSorting

public void setBackEndSorting(List<QuerySortOrder> sortOrder)

Sets the QuerySortOrders to use with backend sorting.

Parameters:

sortOrder - list of sort order information to pass to a query

getBackEndSorting

public List<QuerySortOrder> getBackEndSorting()

Returns the QuerySortOrder to use with backend sorting.

Returns:

an unmodifiable list of sort order information to pass to a query

isPagingEnabled

public boolean isPagingEnabled()

Returns whether paged queries are enabled or not.

When the paged queries are supported, the Query.getPage() and Query.getPageSize() can be used to fetch items from the paged repositories. Otherwise, one should use Query.getOffset() and Query.getLimit(). Paged queries are enabled by default.

Returns:

true for paged queries, false for offset/limit queries

See Also:

setPagingEnabled(boolean)

setPagingEnabled

public void setPagingEnabled(boolean pagingEnabled)

Sets whether paged queries or offset/limit queries will be used.

Parameters:

pagingEnabled - true for paged queries, false for offset/limit queries

getDataProviderSize

protected int getDataProviderSize()

Getter method for determining the item count of the data. Can be overridden by a subclass that uses a specific type of DataProvider and/or query.

Returns:

the size of data provider with current filter

getFilter

protected Object getFilter()

Get the object used for filtering in this data communicator.

Returns:

the filter object of this data communicator

fetchFromProvider

protected Stream<T> fetchFromProvider(int offset,
                                      int limit)

Fetches a list of items from the DataProvider.

NOTE: the limit parameter shows how many items the client wants to fetch, but the actual number of results may be greater, and vary from 0 to pages * pageSize.

Parameters:

offset - the starting index of the range

limit - the desired number of results

Returns:

the list of items in given range

handleDataRefreshEvent

protected void handleDataRefreshEvent(DataChangeEvent.DataRefreshEvent<T> event)