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:

Serializable, HasDisplayData

Enclosing class:

View

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

Not intended for direct use by pipeline authors; 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

Method Summary

Modifier and Type	Method and Description
PCollectionView<T>	apply(PCollection<T> input) Applies this PTransform on the given InputT, and returns its Output.
T	defaultValue() Returns the default value of this transform, or null if there isn't one.
boolean	hasDefaultValue() Returns whether this transform has a default value.
void	validate(PCollection<T> input) Called before invoking apply (which may be intercepted by the runner) to verify this transform is fully specified and applicable to the specified input.
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

getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getKindString, getName, populateDisplayData, toString

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.

validate

public void validate(PCollection<T> input)

Description copied from class: PTransform

Called before invoking apply (which may be intercepted by the runner) to verify this transform is fully specified and applicable to the specified input.

By default, does nothing.

Overrides:

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

apply

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

Description copied from class: PTransform

Applies this PTransform on the given InputT, and returns its Output.

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:

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