org.apache.polygene.api.query

Interface Query<T>

Type Parameters:

T - Entity type

All Superinterfaces:

Iterable<T>

public interface Query<T>
extends Iterable<T>

This represents a Query in an indexing system. It is created from a QueryBuilder, which decides the "where" clause in the query.

Additional limitations, such as paging, ordering, and variables, can be set on a Query before it is executed by calling one of find(), iterator(), or count().

DDD tip: typically Queries are created in the Domain Model and passed to the UI, which sets the order and paging before executing it.

Method Summary

Modifier and Type	Method and Description
long	count() Count how many results would be returned by this Query.
T	find() Get the first Entity that matches the criteria.
Query<T>	firstResult(int firstResult) Set the index of the first result.
<V> V	getVariable(String name) Get the value of a named variable.
Query<T>	maxResults(int maxResults) Set how many results should be returned.
Query<T>	orderBy(OrderBy... segments) Set the ordering rules.
Query<T>	orderBy(Property<?> property) Append an ascending ordering rule to the existing segments.
Query<T>	orderBy(Property<?> property, OrderBy.Order order) Append an ordering rule to the existing segments.
Class<T>	resultType() Get the result type of this Query
Query<T>	setVariable(String name, Object value) Set the value of a named variable.
Stream<T>	stream()

Methods inherited from interface java.lang.Iterable

forEach, iterator, spliterator

Method Detail

orderBy

Query<T> orderBy(OrderBy... segments)

Set the ordering rules. If many segments are used for ordering then they will be applied in order.

Parameters:

segments - the segments to order by

Returns:

the Query

orderBy

Query<T> orderBy(Property<?> property,
                 OrderBy.Order order)

Append an ordering rule to the existing segments.

Parameters:

property - the property to order by

order - the order to apply

Returns:

the Query

orderBy

Query<T> orderBy(Property<?> property)

Append an ascending ordering rule to the existing segments.

Parameters:

property - the property to order by

Returns:

the Query

firstResult

Query<T> firstResult(int firstResult)

Set the index of the first result. Default is 0 (zero).

Parameters:

firstResult - which index to use as the first one

Returns:

the Query

maxResults

Query<T> maxResults(int maxResults)

Set how many results should be returned. Default is that there is no limit set.

Parameters:

maxResults - that shouldbe returned

Returns:

the query

find

T find()
throws QueryExecutionException

Get the first Entity that matches the criteria. This executes the Query.

Returns:

the first found Entity or null if none were found

Throws:

QueryExecutionException - if the query fails

setVariable

Query<T> setVariable(String name,
                     Object value)

Set the value of a named variable.

Parameters:

name - of the variable

value - of the variable

Returns:

the query

getVariable

<V> V getVariable(String name)

Get the value of a named variable.

Type Parameters:

V - Variable type

Parameters:

name - of the variable

Returns:

value of the variable

resultType

Class<T> resultType()

Get the result type of this Query

Returns:

the result type

count

long count()
    throws QueryExecutionException

Count how many results would be returned by this Query. This executes the Query.

Returns:

result count

Throws:

QueryExecutionException - if the query fails

stream

Stream<T> stream()

Returns:

Stream results