com.google.cloud.dataflow.sdk.values

Class PBegin

java.lang.Object

com.google.cloud.dataflow.sdk.values.PBegin

All Implemented Interfaces:

PInput

public class PBegin
extends Object
implements PInput

PBegin is used as the "input" to a root PTransform that is the first operation in a Pipeline, such as TextIO.Read or Create.

Typically created by calling Pipeline.begin() on a Pipeline.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	PBegin(Pipeline pipeline) Constructs a PBegin in the given Pipeline.

Method Summary

Methods

Modifier and Type	Method and Description
<OutputT extends POutput> OutputT	apply(PTransform<? super PBegin,OutputT> t) Applies the given PTransform to this input PBegin, and returns the PTransform's Output.
Collection<? extends PValue>	expand() Expands this PInput into a list of its component input PValues.
void	finishSpecifying() After building, finalizes this PInput to make it ready for being used as an input to a PTransform.
Pipeline	getPipeline() Returns the owning Pipeline of this PInput.
static PBegin	in(Pipeline pipeline) Returns a PBegin in the given Pipeline.

Methods inherited from class java.lang.Object

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

Constructor Detail

PBegin

protected PBegin(Pipeline pipeline)

Constructs a PBegin in the given Pipeline.

Method Detail

in

public static PBegin in(Pipeline pipeline)

Returns a PBegin in the given Pipeline.

apply

public <OutputT extends POutput> OutputT apply(PTransform<? super PBegin,OutputT> t)

Applies the given PTransform to this input PBegin, and returns the PTransform's Output.

getPipeline

public Pipeline getPipeline()

Description copied from interface: PInput

Returns the owning Pipeline of this PInput.

Specified by:

getPipeline in interface PInput

expand

public Collection<? extends PValue> expand()

Description copied from interface: PInput

Expands this PInput into a list of its component input PValues.

A PValue expands to itself.

A tuple or list of PValues (e.g., PCollectionTuple, and PCollectionList) expands to its component PValues.

Not intended to be invoked directly by user code.

Specified by:

expand in interface PInput

finishSpecifying

public void finishSpecifying()

Description copied from interface: PInput

After building, finalizes this PInput to make it ready for being used as an input to a PTransform.

Automatically invoked whenever apply() is invoked on this PInput, so users do not normally call this explicitly.

Specified by:

finishSpecifying in interface PInput