ViewFn (core 2.44.0 API)

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:

java.io.Serializable

Direct Known Subclasses:

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 java.lang.Object
implements java.io.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

All Methods Instance Methods Abstract Methods
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 Detail
  - ViewFn
```
public ViewFn()
```
- Method Detail
  - 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.