sirius.db.mixing.types

Class BaseEntityRef<I,E extends BaseEntity<I>>

java.lang.Object

sirius.db.mixing.types.BaseEntityRef<I,E>

Type Parameters:

I - the generic type of the primary key / id used by the entity

E - the generic type of the referenced entity

Direct Known Subclasses:

ElasticRef, MongoRef, SQLEntityRef

public abstract class BaseEntityRef<I,E extends BaseEntity<I>>
extends Object

Represents a reference from one entity to another.

Instead of directly keeping the entity in a Java field, it is wrapped in an EntityRef. This leads to clean semantics for lazy loading as both the ID and (if fetched) the value are stored in this wrapper.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BaseEntityRef.OnDelete Declares cascade actions which determine what happens if a referenced entity is deleted.

Field Summary

Fields

Modifier and Type	Field and Description
protected BaseEntityRef.OnDelete	deleteHandler
protected I	id
protected Class<E>	type
protected E	value

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BaseEntityRef(Class<E> type, BaseEntityRef.OnDelete deleteHandler)

Method Summary

Modifier and Type	Method and Description
protected abstract I	coerceToId(Object id) Converts the given object into an id.
boolean	containsNonpersistentValue() Determines if the given entity value was not yet persisted to the database.
protected abstract Optional<E>	find(Class<E> type, I id) Performs the lookup of the entity with the given id.
BaseEntityRef.OnDelete	getDeleteHandler() Returns the delete handler.
I	getId() Returns the id of the referenced entity.
Class<E>	getType() Returns the entity type being referenced.
String	getUniqueObjectName() Returns the Unique Object Name for the referenced entity.
E	getValue() Returns the effective entity object which is referenced.
boolean	is(Object entityOrId) Determines if the referenced entity is equal to the given entity or id.
boolean	isEmpty() Opposite of isFilled().
boolean	isFilled() Determines if an entity is referenced.
boolean	isValueLoaded() Determines if the entity object for the referenced id is loaded.
void	setId(I id) Sets the id of the referenced entity.
void	setValue(E value) Sets the entity being referenced.

Methods inherited from class java.lang.Object

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

Field Detail

type

protected Class<E extends BaseEntity<I>> type

deleteHandler

protected BaseEntityRef.OnDelete deleteHandler

id

protected I id

value

protected E extends BaseEntity<I> value

Constructor Detail

BaseEntityRef

protected BaseEntityRef(Class<E> type,
                        BaseEntityRef.OnDelete deleteHandler)

Method Detail

getType

public Class<E> getType()

Returns the entity type being referenced.

Returns:

the entity type being referenced

getDeleteHandler

public BaseEntityRef.OnDelete getDeleteHandler()

Returns the delete handler.

Returns:

the handler which deciedes how to tread deletes of the referenced entity

getId

@Nullable
public I getId()

Returns the id of the referenced entity.

Returns:

the id of the referenced entity or null if no entity is referenced.

setId

public void setId(@Nullable
                  I id)

Sets the id of the referenced entity.

Parameters:

id - the id of the referenced entity or null if no entity is referenced.

getUniqueObjectName

public String getUniqueObjectName()

Returns the Unique Object Name for the referenced entity.

Returns:

the unique object name of the referenced entity or null if the reference is empty.

See Also:

BaseEntity.getUniqueName()

getValue

@Nullable
public E getValue()

Returns the effective entity object which is referenced.

Note, this might cause a database lookup if the entity is not prefetched.

Returns:

the entity being referenced or null if no entity is referenced.

find

protected abstract Optional<E> find(Class<E> type,
                                    I id)

Performs the lookup of the entity with the given id.

Parameters:

type - the type to search for

id - the id to lookup

Returns:

the matching entity wrapped as optional or an empty optional of the entity doesn't exist

setValue

public void setValue(@Nullable
                     E value)

Sets the entity being referenced.

Parameters:

value - the entity being referenced or null if no entity is referenced.

isValueLoaded

public boolean isValueLoaded()

Determines if the entity object for the referenced id is loaded.

Returns:

true if the object is present, false otherwise

isFilled

public boolean isFilled()

Determines if an entity is referenced.

The referenced entity might still not be loaded yet.

Returns:

true if an entity is referenced (the stored id is not null). false otherwise

isEmpty

public boolean isEmpty()

Opposite of isFilled().

Returns:

true if no entity is referenced, false if a non null id is present.

is

public boolean is(Object entityOrId)

Determines if the referenced entity is equal to the given entity or id.

Parameters:

entityOrId - the entity or id to check for

Returns:

true if the entities are the same (based on their id), false otherwise.

coerceToId

protected abstract I coerceToId(@Nonnull
                                Object id)

Converts the given object into an id.

Parameters:

id - the value to coerce

Returns:

the value represented in the correct type

containsNonpersistentValue

public boolean containsNonpersistentValue()

Determines if the given entity value was not yet persisted to the database.

For obvious reasons, a non persisted entity cannot be referenced once the referencing entity is saved.

Returns:

true if the referenced entity was not yet saved to the database, false otherwise