com.vaadin.flow.data.provider

Class DataProviderWrapper<T,F,M>

java.lang.Object

com.vaadin.flow.data.provider.DataProviderWrapper<T,F,M>

Type Parameters:

T - data provider data type

F - wrapper query filter type

M - underlying data provider filter type

All Implemented Interfaces:

DataProvider<T,F>, Serializable

Direct Known Subclasses:

ConfigurableFilterDataProviderWrapper

public abstract class DataProviderWrapper<T,F,M>
extends Object
implements DataProvider<T,F>

Wrapper class for modifying, chaining and replacing filters and sorting in a query. Used to create a suitable Query for the underlying data provider with correct filters and sorting.

Since:

1.0.

Author:

Vaadin Ltd

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected DataProvider<T,M>	dataProvider The actual data provider behind this wrapper.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DataProviderWrapper(DataProvider<T,M> dataProvider) Constructs a filtering wrapper for a data provider.

Method Summary

Modifier and Type	Method and Description
Registration	addDataProviderListener(DataProviderListener<T> listener) Adds a data provider listener.
Stream<T>	fetch(Query<T,F> t) Fetches data from this DataProvider using given query.
protected abstract M	getFilter(Query<T,F> query) Gets the filter that should be used in the modified Query.
Object	getId(T item) Gets an identifier for the given item.
boolean	isInMemory() Gets whether the DataProvider content all available in memory or does it use some external backend.
void	refreshAll() Refreshes all data based on currently available data in the underlying provider.
void	refreshItem(T item) Refreshes the given item.
int	size(Query<T,F> t) Gets the amount of data in this DataProvider.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.vaadin.flow.data.provider.DataProvider

fromCallbacks, fromFilteringCallbacks, fromStream, ofCollection, ofItems, withConfigurableFilter, withConfigurableFilter, withConvertedFilter

Field Detail

dataProvider

protected DataProvider<T,M> dataProvider

The actual data provider behind this wrapper.

Constructor Detail

DataProviderWrapper

protected DataProviderWrapper(DataProvider<T,M> dataProvider)

Constructs a filtering wrapper for a data provider.

Parameters:

dataProvider - the wrapped data provider, not null

Method Detail

isInMemory

public boolean isInMemory()

Description copied from interface: DataProvider

Gets whether the DataProvider content all available in memory or does it use some external backend.

Specified by:

isInMemory in interface DataProvider<T,F>

Returns:

true if all data is in memory; false if not

refreshAll

public void refreshAll()

Description copied from interface: DataProvider

Refreshes all data based on currently available data in the underlying provider.

Specified by:

refreshAll in interface DataProvider<T,F>

refreshItem

public void refreshItem(T item)

Description copied from interface: DataProvider

Refreshes the given item. This method should be used to inform all DataProviderListeners that an item has been updated or replaced with a new instance.

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 DataProvider.getId(Object) should be implemented to return an appropriate identifier.

Specified by:

refreshItem in interface DataProvider<T,F>

Parameters:

item - the item to refresh

See Also:

DataProvider.getId(Object)

getId

public Object getId(T item)

Description copied from interface: DataProvider

Gets an identifier for the given item. This identifier is used by the framework to determine equality between two items.

Default is to use item itself as its own identifier. If the item has Object.equals(Object) and Object.hashCode() implemented in a way that it can be compared to other items, no changes are required.

Note: This method will be called often by the Framework. It should not do any expensive operations.

Specified by:

getId in interface DataProvider<T,F>

Parameters:

item - the item to get identifier for; not null

Returns:

the identifier for given item; not null

addDataProviderListener

public Registration addDataProviderListener(DataProviderListener<T> listener)

Description copied from interface: DataProvider

Adds a data provider listener. The listener is called when some piece of data is updated.

The DataProvider.refreshAll() method fires DataChangeEvent each time when it's called. It allows to update UI components when user changes something in the underlying data.

Specified by:

addDataProviderListener in interface DataProvider<T,F>

Parameters:

listener - the data change listener, not null

Returns:

a registration for the listener

See Also:

DataProvider.refreshAll()

size

public int size(Query<T,F> t)

Description copied from interface: DataProvider

Gets the amount of data in this DataProvider.

Specified by:

size in interface DataProvider<T,F>

Parameters:

t - query with sorting and filtering

Returns:

the size of the data provider

fetch

public Stream<T> fetch(Query<T,F> t)

Description copied from interface: DataProvider

Fetches data from this DataProvider using given query.

Specified by:

fetch in interface DataProvider<T,F>

Parameters:

t - given query to request data

Returns:

the result of the query request: a stream of data objects, not null

getFilter

protected abstract M getFilter(Query<T,F> query)

Gets the filter that should be used in the modified Query.

Parameters:

query - the current query

Returns:

filter for the modified Query