/*
* Copyright (c) 2007-2013 Concurrent, Inc. All Rights Reserved.
*
* Project and contact information: http://www.cascading.org/
*
* This file is part of the Cascading project.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cascading.pattern.ensemble.function;
import cascading.operation.expression.ExpressionFunction;
import cascading.pipe.Each;
import cascading.pipe.Pipe;
import cascading.pipe.SubAssembly;
import cascading.tuple.Fields;
/**
* Class InsertGUID creates a globally unique ID by calling {@link java.util.UUID#randomUUID()}.
* <p/>
* This Function also returns {@code false} for {@link cascading.operation.Operation#isSafe()}, preventing
* duplicate ids from being generated for the same record.
*/
public class InsertGUID extends SubAssembly
{
public InsertGUID( Pipe previous, Fields declaredFields )
{
super( previous );
String expression = "java.util.UUID.randomUUID().toString()";
ExpressionFunction expressionFunction = new ExpressionFunction( declaredFields, expression )
{
@Override
public boolean isSafe()
{
return false;
}
};
previous = new Each( previous, Fields.NONE, expressionFunction, Fields.ALL );
setTails( previous );
}
}