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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (APEXMALHAR-2010) Add transform operator
Date Fri, 18 Mar 2016 13:10:33 GMT

    [ https://issues.apache.org/jira/browse/APEXMALHAR-2010?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15201447#comment-15201447
] 

ASF GitHub Bot commented on APEXMALHAR-2010:
--------------------------------------------

Github user sandeepdeshmukh commented on a diff in the pull request:

    https://github.com/apache/incubator-apex-malhar/pull/209#discussion_r56652885
  
    --- Diff: library/src/main/java/com/datatorrent/lib/transform/TransformOperator.java ---
    @@ -0,0 +1,172 @@
    +/**
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you 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 com.datatorrent.lib.transform;
    +
    +import java.lang.reflect.Field;
    +import java.util.HashMap;
    +import java.util.LinkedList;
    +import java.util.List;
    +import java.util.Map;
    +
    +import org.apache.commons.lang3.ClassUtils;
    +
    +import com.datatorrent.api.Context;
    +import com.datatorrent.api.DefaultInputPort;
    +import com.datatorrent.api.DefaultOutputPort;
    +import com.datatorrent.api.Operator;
    +import com.datatorrent.api.annotation.InputPortFieldAnnotation;
    +import com.datatorrent.api.annotation.OutputPortFieldAnnotation;
    +import com.datatorrent.common.util.BaseOperator;
    +import com.datatorrent.lib.expression.Expression;
    +import com.datatorrent.lib.util.PojoUtils;
    +
    +/**
    + * This operator can transform given POJO using provided expressions and
    + * return a final POJO as a return of transformation process.
    + *
    + * Following are the mandatory fields that needs to be set for TransformOperator to work:
    + * <ul>
    + *   <li><b>expressionMap</b> : Set how the transformation should happen</li>
    + *   <li><b>inputPort.attr.TUPLE_CLASS</b>: Set class type at input
port</li>
    + *   <li><b>outputPort.attr.TUPLE_CLASS</b> : Set class type at output
port</li>
    + * </ul>
    + *
    + * The operator uses interaction via {@link Expression} and {@link PojoUtils} to transform
given POJO.
    + */
    +public class TransformOperator extends BaseOperator implements Operator.ActivationListener
    +{
    +  private Map<String, String> expressionMap = new HashMap<>();
    +  private List<String> expressionImports = new LinkedList<>();
    +
    +  private transient Map<PojoUtils.Setter, Expression> transformationMap = new HashMap<>();
    +  private Class<?> inputClass;
    +  private Class<?> outputClass;
    +
    +  public TransformOperator()
    +  {
    +    expressionImports.add("java.lang.Math.*");
    +    expressionImports.add("org.apache.commons.lang3.StringUtils.*");
    +  }
    +
    +  @InputPortFieldAnnotation(schemaRequired = true) public final transient DefaultInputPort<Object>
input = new DefaultInputPort<Object>()
    +  {
    +    @Override public void setup(Context.PortContext context)
    +    {
    +      inputClass = context.getValue(Context.PortContext.TUPLE_CLASS);
    +    }
    +
    +    @Override public void process(Object o)
    +    {
    +      processTuple(o);
    +    }
    +  };
    +
    +  @OutputPortFieldAnnotation(schemaRequired = true) public final transient DefaultOutputPort<Object>
output = new DefaultOutputPort<Object>()
    +  {
    +    @Override public void setup(Context.PortContext context)
    +    {
    +      outputClass = context.getValue(Context.PortContext.TUPLE_CLASS);
    +    }
    +  };
    +
    +  private void processTuple(Object in)
    +  {
    +    if (!inputClass.isAssignableFrom(in.getClass())) {
    +      throw new RuntimeException(
    +          "Unexpected tuple received. Received class: " + in.getClass() + ". Expected
class: " + inputClass.getClass());
    +    }
    +
    +    Object out;
    +    try {
    +      out = outputClass.newInstance();
    +    } catch (InstantiationException | IllegalAccessException e) {
    +      throw new RuntimeException("Failed to create new object", e);
    +    }
    +
    +    for (Map.Entry<PojoUtils.Setter, Expression> entry : transformationMap.entrySet())
{
    +      PojoUtils.Setter set = entry.getKey();
    +      Expression expr = entry.getValue();
    +      set.set(out, expr.execute(in));
    +    }
    --- End diff --
    
    Is there any default Identity function? 
    For example: If input POJO has a, b fields and output POJO has a,b,c and the expression
is defined for  c = a+b.
    Will output.a=input.a and output.b=input.b be auto-set. This can always be overridden
by say a = a-b.


> Add transform operator
> ----------------------
>
>                 Key: APEXMALHAR-2010
>                 URL: https://issues.apache.org/jira/browse/APEXMALHAR-2010
>             Project: Apache Apex Malhar
>          Issue Type: New Feature
>          Components: algorithms
>    Affects Versions: 3.4.0
>            Reporter: Chinmay Kolhatkar
>            Assignee: Chinmay Kolhatkar
>
> Add transform operator
> Details to be added soon once the mailing thread reaching conclusion:
> http://mail-archives.apache.org/mod_mbox/incubator-apex-dev/201603.mbox/%3CCABAipVZUdRGx5dS35bYPN46koLQU5gSLgbCeRH8aM_y9ANRU2w%40mail.gmail.com%3E



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