Package org.apache.beam.sdk.transforms

Class ViewFn<PrimitiveViewT,ViewT>

java.lang.Object

org.apache.beam.sdk.transforms.ViewFn<PrimitiveViewT,ViewT>

Type Parameters:

PrimitiveViewT - the type of the underlying primitive view required

ViewT - the type of the value(s) accessible via this PCollectionView

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

PCollectionViews.InMemoryListFromMultimapViewFn, PCollectionViews.InMemoryListViewFn, PCollectionViews.InMemoryMapFromVoidKeyViewFn, PCollectionViews.InMemoryMapViewFn, PCollectionViews.InMemoryMultimapFromVoidKeyViewFn, PCollectionViews.InMemoryMultimapViewFn, PCollectionViews.IterableBackedListViewFn, PCollectionViews.IterableViewFn, PCollectionViews.IterableViewFn2, PCollectionViews.ListViewFn, PCollectionViews.ListViewFn2, PCollectionViews.MapViewFn, PCollectionViews.MapViewFn2, PCollectionViews.MultimapViewFn, PCollectionViews.MultimapViewFn2, PCollectionViews.SingletonViewFn, PCollectionViews.SingletonViewFn2

@Internal
public abstract class ViewFn<PrimitiveViewT,ViewT>
extends Object
implements Serializable

For internal use only; no backwards-compatibility guarantees.

A function to adapt a primitive "view" of a PCollection - some materialization specified in the Beam model and implemented by the runner - to a user-facing view type for side input.

Both the underlying primitive view and the user-facing view are immutable.

The most common case is using the View transforms to prepare a PCollection for use as a side input to ParDo. See View.asSingleton(), View.asIterable(), and View.asMap() for more detail on specific views available in the SDK.

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
ViewFn()

Method Summary

Modifier and Type	Method	Description
abstract ViewT	apply(PrimitiveViewT primitiveViewT)	A function to adapt a primitive view type to a desired view type.
abstract Materialization<PrimitiveViewT>	getMaterialization()	Gets the materialization of this ViewFn.
abstract TypeDescriptor<ViewT>	getTypeDescriptor()	Return the TypeDescriptor describing the output of this fn.

Methods inherited from class java.lang.Object

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

Constructor Details

ViewFn

public ViewFn()

Method Details

getMaterialization

public abstract Materialization<PrimitiveViewT> getMaterialization()

Gets the materialization of this ViewFn.

apply

public abstract ViewT apply(PrimitiveViewT primitiveViewT)

A function to adapt a primitive view type to a desired view type.

getTypeDescriptor

public abstract TypeDescriptor<ViewT> getTypeDescriptor()

Return the TypeDescriptor describing the output of this fn.