com.google.cloud.dataflow.sdk.io

Class DatastoreIO.DatastoreReader

java.lang.Object

com.google.cloud.dataflow.sdk.io.DatastoreIO.DatastoreReader

All Implemented Interfaces:

Source.Reader<com.google.api.services.datastore.DatastoreV1.Entity>, java.lang.AutoCloseable

Enclosing class:

DatastoreIO

public static class DatastoreIO.DatastoreReader
extends java.lang.Object
implements Source.Reader<com.google.api.services.datastore.DatastoreV1.Entity>

A reader over the records from a query of the datastore.

Constructor Summary

Constructors

Constructor and Description
DatastoreIO.DatastoreReader(com.google.api.services.datastore.DatastoreV1.Query query, com.google.api.services.datastore.client.Datastore datastore) Returns a DatastoreIterator with query and Datastore object set.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	advance() Advances the iterator to the next valid record.
void	close() Closes the iterator.
com.google.api.services.datastore.DatastoreV1.Entity	getCurrent() Returns the value of the data item which was read by the last Source.Reader.start() or Source.Reader.advance() call.
boolean	start() Initializes the reader and advances the reader to the first record.

Methods inherited from class java.lang.Object

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

Constructor Detail

DatastoreIO.DatastoreReader

public DatastoreIO.DatastoreReader(com.google.api.services.datastore.DatastoreV1.Query query,
                           com.google.api.services.datastore.client.Datastore datastore)

Returns a DatastoreIterator with query and Datastore object set.

Parameters:

query - the query to select records.

datastore - a datastore connection to use.

Method Detail

getCurrent

public com.google.api.services.datastore.DatastoreV1.Entity getCurrent()

Description copied from interface: Source.Reader

Returns the value of the data item which was read by the last Source.Reader.start() or Source.Reader.advance() call.

Specified by:

getCurrent in interface Source.Reader<com.google.api.services.datastore.DatastoreV1.Entity>

start

public boolean start()
              throws java.io.IOException

Description copied from interface: Source.Reader

Initializes the reader and advances the reader to the first record.

This method should be called exactly once. The invocation should occur prior to calling Source.Reader.advance() or Source.Reader.getCurrent(). This method may perform expensive operations that are needed to initialize the reader.

Specified by:

start in interface Source.Reader<com.google.api.services.datastore.DatastoreV1.Entity>

Returns:

true if a record was read, false if we're at the end of input.

Throws:

java.io.IOException

advance

public boolean advance()
                throws java.io.IOException

Description copied from interface: Source.Reader

Advances the iterator to the next valid record. Invalidates the result of the previous Source.Reader.getCurrent() call.

Specified by:

advance in interface Source.Reader<com.google.api.services.datastore.DatastoreV1.Entity>

Returns:

true if a record was read, false if we're at the end of input.

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Description copied from interface: Source.Reader

Closes the iterator. The iterator cannot be used after this method was called.

Specified by:

close in interface Source.Reader<com.google.api.services.datastore.DatastoreV1.Entity>

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.io.IOException