sirius.db.mixing.query

Class BaseQuery<Q,E extends BaseEntity<?>>

java.lang.Object

sirius.db.mixing.query.BaseQuery<Q,E>

Type Parameters:

Q - the generic parameter of the effective query class

E - the generic type of the entity being queried

Direct Known Subclasses:

Query, TransformedQuery

public abstract class BaseQuery<Q,E extends BaseEntity<?>>
extends Object

Base class for queries within mixing.

Field Summary

Fields

Modifier and Type	Field and Description
protected EntityDescriptor	descriptor Contains the descriptor of the entities being queried.
protected int	limit Contains the max number of items to fetch (or 0 for "unlimited")
static int	MAX_LIST_SIZE Contains the maximal number of elements to be returned in queryList().
protected static Mixing	mixing
protected int	skip Contains the the number of items to skip before items are added to the result

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BaseQuery(EntityDescriptor descriptor) Creates a new query for entities of the given type.

Method Summary

Modifier and Type	Method and Description
protected void	failOnOverflow(List<E> result)
Optional<E>	first() Returns the first item matched by the query.
EntityDescriptor	getDescriptor() Returns the underlying descriptor
protected sirius.kernel.commons.Limit	getLimit()
abstract void	iterate(Function<E,Boolean> handler) Calls the given function on all items in the result, as long as it returns true.
void	iterateAll(Consumer<E> consumer) Calls the given consumer on all items in the result.
Q	limit(int limit) Specifies the max. number of items to fetch.
Optional<E>	one() Returns the single item matched by the query.
E	queryFirst() Returns the first item matched by the query.
List<E>	queryList() Returns a list of all items in the result.
E	queryOne() Returns the first item matched by the query.
Q	skip(int skip) Specifies the number of items to skip before items are added to the result.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_LIST_SIZE

public static final int MAX_LIST_SIZE

Contains the maximal number of elements to be returned in queryList().

For larger results iterate(Function) mit be used as it can be more efficient

See Also:

Constant Field Values

limit

protected int limit

Contains the max number of items to fetch (or 0 for "unlimited")

skip

protected int skip

Contains the the number of items to skip before items are added to the result

mixing

protected static Mixing mixing

descriptor

protected final EntityDescriptor descriptor

Contains the descriptor of the entities being queried.

Constructor Detail

BaseQuery

protected BaseQuery(EntityDescriptor descriptor)

Creates a new query for entities of the given type.

Parameters:

descriptor - the descriptor of the entity type to query

Method Detail

getLimit

protected sirius.kernel.commons.Limit getLimit()

getDescriptor

public EntityDescriptor getDescriptor()

Returns the underlying descriptor

Returns:

the descriptor of the entities being queried.

limit

public Q limit(int limit)

Specifies the max. number of items to fetch.

Parameters:

limit - the max. number of items to fetch. Value <= 0 indicate "unlimited".

Returns:

the query itself for fluent method calls

skip

public Q skip(int skip)

Specifies the number of items to skip before items are added to the result.

Parameters:

skip - the number of items to skip. Value <= 0 are ignored.

Returns:

the query itself for fluent method calls

iterate

public abstract void iterate(Function<E,Boolean> handler)

Calls the given function on all items in the result, as long as it returns true.

Note that this method is intended for large results as not all items in the result need to be kept in memory when iterating through them.

Parameters:

handler - the handle to be invoked for each item in the result

iterateAll

public void iterateAll(Consumer<E> consumer)

Calls the given consumer on all items in the result.

Note that this method is intended for large results as not all items in the result need to be kept in memory when iterating through them.

Parameters:

consumer - the handle to be invoked for each item in the result

queryList

public List<E> queryList()

Returns a list of all items in the result.

Note that large results should be processed using iterate(Function) or iterateAll(Consumer) as they are more memory efficient.

Returns:

a list of items in the query or an empty list if the query did not match any items

failOnOverflow

protected void failOnOverflow(List<E> result)

first

public Optional<E> first()

Returns the first item matched by the query.

Returns:

the first item matched by the query wrapped as Optional. Returns an empty optional, if the query has no matches.

queryFirst

public E queryFirst()

Returns the first item matched by the query.

Returns:

the first item matched by the query or null if there are no matches.

one

public Optional<E> one()

Returns the single item matched by the query.

Returns:

the first item matched by the query wrapped as Optional. Returns an empty optional, if the query has no or several matches.

queryOne

public E queryOne()

Returns the first item matched by the query.

Returns:

the first item matched by the query or null if the query has no or several matches.