ATLAS-2875: Implement clear attribute value transformer for Atlas Entity Transformer

intg/src/main/java/org/apache/atlas/entitytransform/Action.java

@@ -31,6 +31,7 @@ public abstract class Action {
     private static final String ACTION_NAME_REPLACE_PREFIX = "REPLACE_PREFIX";
     private static final String ACTION_NAME_TO_LOWER       = "TO_LOWER";
     private static final String ACTION_NAME_TO_UPPER       = "TO_UPPER";
+    private static final String ACTION_NAME_CLEAR          = "CLEAR";
 
     protected final String attributeName;
 
@@ -80,6 +81,10 @@ public abstract class Action {
                 ret = new SetAction(key, actionValue);
             break;
 
+            case ACTION_NAME_CLEAR:
+                ret = new ClearAction(key);
+                break;
+
             default:
                 ret = new SetAction(key, value); // treat unspecified/unknown action as 'SET'
             break;
@@ -196,4 +201,17 @@ public abstract class Action {
             }
         }
     }
+
+    public static class ClearAction extends Action {
+        public ClearAction(String attributeName) {
+            super(attributeName);
+        }
+
+        @Override
+        public void apply(AtlasTransformableEntity entity) {
+            if (isValid() && entity.hasAttribute(attributeName)) {
+                entity.setAttribute(attributeName, null);
+            }
+        }
+    }
 }

intg/src/main/java/org/apache/atlas/entitytransform/BaseEntityHandler.java

@@ -95,6 +95,10 @@ public class BaseEntityHandler {
             }
         }
 
+        if (CollectionUtils.isEmpty(ret)) {
+            ret.add(new BaseEntityHandler(transformers));
+        }
+
         if (LOG.isDebugEnabled()) {
             LOG.debug("<== BaseEntityHandler.createEntityHandlers(transforms={}): ret.size={}", transforms, ret.size());
         }
@@ -158,6 +162,10 @@ public class BaseEntityHandler {
             }
         }
 
+        public boolean hasAttribute(String attributeName) {
+            return getAttribute(attributeName) != null;
+        }
+
         public void transformComplete() {
             // implementations can override to set value of computed-attributes
         }

intg/src/main/java/org/apache/atlas/entitytransform/Condition.java

@@ -31,6 +31,7 @@ public abstract class Condition {
     private static final String CONDITION_NAME_EQUALS_IGNORE_CASE      = "EQUALS_IGNORE_CASE";
     private static final String CONDITION_NAME_STARTS_WITH             = "STARTS_WITH";
     private static final String CONDITION_NAME_STARTS_WITH_IGNORE_CASE = "STARTS_WITH_IGNORE_CASE";
+    private static final String CONDITION_NAME_HAS_VALUE               = "HAS_VALUE";
 
     protected final String attributeName;
 
@@ -75,6 +76,10 @@ public abstract class Condition {
                 ret = new StartsWithIgnoreCaseCondition(key, conditionValue);
             break;
 
+            case CONDITION_NAME_HAS_VALUE:
+                ret = new HasValueCondition(key, conditionValue);
+                break;
+
             default:
                 ret = new EqualsCondition(key, value); // treat unspecified/unknown condition as 'EQUALS'
             break;
@@ -158,4 +163,21 @@ public abstract class Condition {
             return attributeValue != null && StringUtils.startsWithIgnoreCase(attributeValue.toString(), this.prefix);
         }
     }
+
+    public static class HasValueCondition extends Condition {
+        protected final String attributeValue;
+
+        public HasValueCondition(String attributeName, String attributeValue) {
+            super(attributeName);
+
+            this.attributeValue = attributeValue;
+        }
+
+        @Override
+        public boolean matches(AtlasTransformableEntity entity) {
+            Object attributeValue = entity != null ? entity.getAttribute(attributeName) : null;
+
+            return attributeValue != null ? StringUtils.isNotEmpty(attributeValue.toString()) : false;
+        }
+    }
 }

intg/src/test/java/org/apache/atlas/entitytransform/TransformationHandlerTest.java

@@ -25,9 +25,12 @@ import org.testng.annotations.Test;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import static org.apache.atlas.entitytransform.TransformationConstants.HDFS_PATH;
+import static org.apache.atlas.entitytransform.TransformationConstants.HIVE_TABLE;
 
 public class TransformationHandlerTest {
     @Test
@@ -102,6 +105,100 @@ public class TransformationHandlerTest {
     }
 
     @Test
+    public void testHiveTableClearAttributeHandler() {
+        // clear replicatedTo attribute for hive_table entities
+        AttributeTransform p1 = new AttributeTransform(Collections.singletonMap("hive_table.replicatedTo", "HAS_VALUE:"),
+                                                       Collections.singletonMap("hive_table.replicatedTo", "CLEAR:"));
+
+        List<BaseEntityHandler> handlers = initializeHandlers(Collections.singletonList(p1));
+
+        List<AtlasEntity> entities = getAllEntities();
+
+        for (AtlasEntity entity : entities) {
+            String  replicatedTo = (String) entity.getAttribute("replicatedTo");
+
+            if (entity.getTypeName() == HIVE_TABLE) {
+                Assert.assertTrue(StringUtils.isNotEmpty(replicatedTo));
+            }
+
+            applyTransforms(entity, handlers);
+
+            String transformedValue = (String) entity.getAttribute("replicatedTo");
+
+            if (entity.getTypeName() == HIVE_TABLE) {
+                Assert.assertTrue(StringUtils.isEmpty(transformedValue));
+            }
+        }
+    }
+
+    @Test
+    public void testEntityClearAttributesActionWithNoCondition() {
+        // clear replicatedFrom attribute for hive_table entities without any condition
+        Map<String, String> actions = new HashMap<String, String>() {{  put("__entity.replicatedTo", "CLEAR:");
+                                                                        put("__entity.replicatedFrom", "CLEAR:"); }};
+
+        AttributeTransform transform = new AttributeTransform(null, actions);
+
+        List<BaseEntityHandler> handlers = initializeHandlers(Collections.singletonList(transform));
+
+
+        List<AtlasEntity> entities = getAllEntities();
+
+        for (AtlasEntity entity : entities) {
+            String replicatedTo   = (String) entity.getAttribute("replicatedTo");
+            String replicatedFrom = (String) entity.getAttribute("replicatedFrom");
+
+            if (entity.getTypeName() == HIVE_TABLE) {
+                Assert.assertTrue(StringUtils.isNotEmpty(replicatedTo));
+                Assert.assertTrue(StringUtils.isNotEmpty(replicatedFrom));
+            }
+
+            applyTransforms(entity, handlers);
+
+            replicatedTo   = (String) entity.getAttribute("replicatedTo");
+            replicatedFrom = (String) entity.getAttribute("replicatedFrom");
+
+            if (entity.getTypeName() == HIVE_TABLE) {
+                Assert.assertTrue(StringUtils.isEmpty(replicatedTo));
+                Assert.assertTrue(StringUtils.isEmpty(replicatedFrom));
+            }
+        }
+    }
+
+    @Test
+    public void testEntityClearAttributesActionWithNoTypeNameAndNoCondition() {
+        // clear replicatedFrom attribute for hive_table entities without any condition
+        Map<String, String> actions = new HashMap<String, String>() {{  put("replicatedTo", "CLEAR:");
+                                                                        put("replicatedFrom", "CLEAR:"); }};
+
+        AttributeTransform transform = new AttributeTransform(null, actions);
+
+        List<BaseEntityHandler> handlers = initializeHandlers(Collections.singletonList(transform));
+
+        List<AtlasEntity> entities = getAllEntities();
+
+        for (AtlasEntity entity : entities) {
+            String replicatedTo   = (String) entity.getAttribute("replicatedTo");
+            String replicatedFrom = (String) entity.getAttribute("replicatedFrom");
+
+            if (entity.getTypeName() == HIVE_TABLE) {
+                Assert.assertTrue(StringUtils.isNotEmpty(replicatedTo));
+                Assert.assertTrue(StringUtils.isNotEmpty(replicatedFrom));
+            }
+
+            applyTransforms(entity, handlers);
+
+            replicatedTo   = (String) entity.getAttribute("replicatedTo");
+            replicatedFrom = (String) entity.getAttribute("replicatedFrom");
+
+            if (entity.getTypeName() == HIVE_TABLE) {
+                Assert.assertTrue(StringUtils.isEmpty(replicatedTo));
+                Assert.assertTrue(StringUtils.isEmpty(replicatedFrom));
+            }
+        }
+    }
+
+    @Test
     public void testHdfsPathNameReplacePrefixHandler() {
         // Prefix replace hdfs_path name from /aa/bb/ to /xx/yy/
         AttributeTransform p1 = new AttributeTransform(Collections.singletonMap("hdfs_path.name", "STARTS_WITH: /aa/bb/"),
@@ -338,6 +435,8 @@ public class TransformationHandlerTest {
         entity.setAttribute("tableType", "EXTERNAL_TABLE");
         entity.setAttribute("createTime", "1535656355000");
         entity.setAttribute("retention", 0);
+        entity.setAttribute("replicatedTo", "[{\"guid\":\"f378cfa5-c4aa-4699-a733-8f11d2f089cd\",\"typeName\":\"AtlasServer\"},{\"guid\":\"58e42789-ea3e-4eaa-a0c4-d38d8632e548\",\"typeName\":\"AtlasServer\"}]");
+        entity.setAttribute("replicatedFrom", "[{\"guid\":\"f378cfa5-c4aa-4699-a733-8f11d2f089cd\",\"typeName\":\"AtlasServer\"},{\"guid\":\"58e42789-ea3e-4eaa-a0c4-d38d8632e548\",\"typeName\":\"AtlasServer\"}]");
 
         return entity;
     }