com.speedment.runtime.field.method

Interface FindFromNullable<ENTITY,FK_ENTITY>

Type Parameters:

ENTITY - the source entity

FK_ENTITY - the target entity

All Superinterfaces:

Function<ENTITY,Stream<FK_ENTITY>>

public interface FindFromNullable<ENTITY,FK_ENTITY>
extends Function<ENTITY,Stream<FK_ENTITY>>

A handle for a find-operation that can be replaced runtime to optimize a Stream. Formally, a FindFrom has the following signature: FK_ENTITY apply(ENTITY entity);

Each FindFrom contains metadata of which fields it compares to determine the mapping as well as a reference to the foreign manager.

FindFromNullable is a specialization of FindFrom that is used to signal that the referenced entity might not exist.

Since:

3.0.10

Author:

Emil Forslund

Method Summary

Modifier and Type	Method and Description
Stream<FK_ENTITY>	apply(ENTITY entity) Applies this method, locating the referenced entity and returning it as a singleton stream if found.
FK_ENTITY	applyOrThrow(ENTITY entity) Applies this method, returning the referenced entity.
Field<ENTITY>	getSourceField() Returns the field that the stream originates from.
TableIdentifier<FK_ENTITY>	getTableIdentifier() Returns the identifier for the referenced (foreign) table.
Field<FK_ENTITY>	getTargetField() Returns the field that the stream references.
boolean	isPresent(ENTITY entity) Returns true if the apply(Object)-method will return a stream with a value.

Methods inherited from interface java.util.function.Function

andThen, compose, identity

Method Detail

getTableIdentifier

TableIdentifier<FK_ENTITY> getTableIdentifier()

Returns the identifier for the referenced (foreign) table.

Returns:

target (foreign) table identifier

getSourceField

Field<ENTITY> getSourceField()

Returns the field that the stream originates from.

In the following example, foo is the source:

      foos.stream()
          .flatMap(foo.findBars()) // findBars returns FindFromNullable<Foo, Bar>
          .forEach(...);
 

Returns:

the source field

getTargetField

Field<FK_ENTITY> getTargetField()

Returns the field that the stream references.

In the following example, bar is the target: foos.stream() .flatMap(foo.findBars()) // findBars returns Streamer<Foo, Bar> .forEach(...);

Returns:

the target field

isPresent

boolean isPresent(ENTITY entity)

Returns true if the apply(Object)-method will return a stream with a value. Otherwise, false is returned.

Parameters:

entity - the entity to locate a foreign entity for

Returns:

singleton or empty stream

applyOrThrow

FK_ENTITY applyOrThrow(ENTITY entity)
                throws IllegalArgumentException

Applies this method, returning the referenced entity. If no entity was referenced, then an exception is thrown. This method should therefore not be invoked unless the status of the availability of the entity has been checked with isPresent(Object).

Another way of retrieving the referenced entity is to use the apply(Object)-method.

Parameters:

entity - the entity to locate a foreign entity for

Returns:

the referenced foreign entity

Throws:

IllegalArgumentException - if no foreign entity was referenced

apply

Stream<FK_ENTITY> apply(ENTITY entity)

Applies this method, locating the referenced entity and returning it as a singleton stream if found. If no entity was referenced, an empty stream will be returned.

Specified by:

apply in interface Function<ENTITY,Stream<FK_ENTITY>>

Parameters:

entity - the entity to locate a foreign entity for

Returns:

singleton or empty stream