Package com.vaadin.data.provider

Interface HierarchicalDataProvider<T,F>

Type Parameters:

T - data type

F - filter type

All Superinterfaces:

DataProvider<T,F>, Serializable

All Known Subinterfaces:

BackEndHierarchicalDataProvider<T,F>

All Known Implementing Classes:

AbstractBackEndHierarchicalDataProvider, AbstractHierarchicalDataProvider, TreeDataProvider

public interface HierarchicalDataProvider<T,F>
extends DataProvider<T,F>

A common interface for fetching hierarchical data from a data source, such as an in-memory collection or a backend database.

Since:

8.1

Author:

Vaadin Ltd

Method Summary

Modifier and Type	Method	Description
default Stream<T>	fetch(Query<T,F> query)	Fetches data from this HierarchicalDataProvider using given query.
Stream<T>	fetchChildren(HierarchicalQuery<T,F> query)	Fetches data from this HierarchicalDataProvider using given query.
int	getChildCount(HierarchicalQuery<T,F> query)	Get the number of immediate child data items for the parent item returned by a given query.
boolean	hasChildren(T item)	Check whether a given item has any children associated with it.
default int	size(Query<T,F> query)	Get the number of immediate child data items for the parent item returned by a given query.

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

addDataProviderListener, getId, isInMemory, refreshAll, refreshItem, withConfigurableFilter, withConfigurableFilter, withConvertedFilter

Method Detail

size

default int size(Query<T,F> query)

Get the number of immediate child data items for the parent item returned by a given query.

Specified by:

size in interface DataProvider<T,F>

Parameters:

query - given query to request the count for

Returns:

the count of child data items for the data item HierarchicalQuery.getParent()

Throws:

IllegalArgumentException - if the query is not of type HierarchicalQuery

fetch

default Stream<T> fetch(Query<T,F> query)

Fetches data from this HierarchicalDataProvider using given query. Only the immediate children of HierarchicalQuery.getParent() will be returned.

NOTE: If your data request is likely to involve I/O channels, see DataProvider.fetch(Query) for instructions on how to handle the stream without risking resource leaks.

Specified by:

fetch in interface DataProvider<T,F>

Parameters:

query - given query to request data with

Returns:

a stream of data objects resulting from the query

Throws:

IllegalArgumentException - if the query is not of type HierarchicalQuery

getChildCount

int getChildCount(HierarchicalQuery<T,F> query)

Get the number of immediate child data items for the parent item returned by a given query.

Parameters:

query - given query to request the count for

Returns:

the count of child data items for the data item HierarchicalQuery.getParent()

fetchChildren

Stream<T> fetchChildren(HierarchicalQuery<T,F> query)

Fetches data from this HierarchicalDataProvider using given query. Only the immediate children of HierarchicalQuery.getParent() will be returned.

NOTE: If your data request is likely to involve I/O channels, see DataProvider.fetch(Query) for instructions on how to handle the stream without risking resource leaks.

Parameters:

query - given query to request data with

Returns:

a stream of data objects resulting from the query

hasChildren

boolean hasChildren(T item)

Check whether a given item has any children associated with it.

Parameters:

item - the item to check for children

Returns:

whether the given item has children