org.apache.beam.sdk.options

Interface ValueProvider<T>

All Superinterfaces:

java.io.Serializable

All Known Implementing Classes:

ValueProvider.NestedValueProvider, ValueProvider.RuntimeValueProvider, ValueProvider.StaticValueProvider

public interface ValueProvider<T>
extends java.io.Serializable

A ValueProvider abstracts the notion of fetching a value that may or may not be currently available.

This can be used to parameterize transforms that only read values in at runtime, for example.

A common task is to create a PCollection containing the value of this ValueProvider regardless of whether it's accessible at construction time or not. For that, use Create.ofProvider(org.apache.beam.sdk.options.ValueProvider<T>, org.apache.beam.sdk.coders.Coder<T>).

For unit-testing a transform against a ValueProvider that only becomes available at runtime, use TestPipeline.newProvider(T).

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ValueProvider.Deserializer For internal use only; no backwards compatibility guarantees.
static class	ValueProvider.NestedValueProvider<T,X> ValueProvider.NestedValueProvider is an implementation of ValueProvider that allows for wrapping another ValueProvider object.
static class	ValueProvider.RuntimeValueProvider<T> ValueProvider.RuntimeValueProvider is an implementation of ValueProvider that allows for a value to be provided at execution time rather than at graph construction time.
static class	ValueProvider.Serializer For internal use only; no backwards compatibility guarantees.
static class	ValueProvider.StaticValueProvider<T> ValueProvider.StaticValueProvider is an implementation of ValueProvider that allows for a static value to be provided.

Method Summary

Modifier and Type	Method and Description
T	get() Returns the runtime value wrapped by this ValueProvider in case it is isAccessible(), otherwise fails.
boolean	isAccessible() Whether the contents of this ValueProvider is currently available via get().

Method Detail

get

T get()

Returns the runtime value wrapped by this ValueProvider in case it is isAccessible(), otherwise fails.

isAccessible

boolean isAccessible()

Whether the contents of this ValueProvider is currently available via get().