org.apache.beam.sdk.transforms

Class View.AsSingleton<T>

java.lang.Object

org.apache.beam.sdk.transforms.PTransform<PCollection<T>,PCollectionView<T>>

org.apache.beam.sdk.transforms.View.AsSingleton<T>

All Implemented Interfaces:

java.io.Serializable, HasDisplayData

Enclosing class:

View

@Internal
public static class View.AsSingleton<T>
extends PTransform<PCollection<T>,PCollectionView<T>>

For internal use only; no backwards-compatibility guarantees.

Public only so a PipelineRunner may override its behavior.

See View.asSingleton().

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.beam.sdk.transforms.PTransform

name, resourceHints

Method Summary

Modifier and Type	Method and Description
T	defaultValue() Returns the default value of this transform, or null if there isn't one.
PCollectionView<T>	expand(PCollection<T> input) Override this method to specify how this PTransform should be expanded on the given InputT.
boolean	hasDefaultValue() Returns whether this transform has a default value.
View.AsSingleton<T>	withDefaultValue(T defaultValue) Default value to return for windows with no value in them.

Methods inherited from class org.apache.beam.sdk.transforms.PTransform

compose, compose, getAdditionalInputs, getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getKindString, getName, getResourceHints, populateDisplayData, setResourceHints, toString, validate

Methods inherited from class java.lang.Object

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

Method Detail

hasDefaultValue

public boolean hasDefaultValue()

Returns whether this transform has a default value.

defaultValue

public T defaultValue()

Returns the default value of this transform, or null if there isn't one.

withDefaultValue

public View.AsSingleton<T> withDefaultValue(T defaultValue)

Default value to return for windows with no value in them.

expand

public PCollectionView<T> expand(PCollection<T> input)

Description copied from class: PTransform

Override this method to specify how this PTransform should be expanded on the given InputT.

NOTE: This method should not be called directly. Instead apply the PTransform should be applied to the InputT using the apply method.

Composite transforms, which are defined in terms of other transforms, should return the output of one of the composed transforms. Non-composite transforms, which do not apply any transforms internally, should return a new unbound output and register evaluators (via backend-specific registration methods).

Specified by:

expand in class PTransform<PCollection<T>,PCollectionView<T>>