support navigation from an instance to a trait

repository/src/main/scala/org/apache/hadoop/metadata/query/Expressions.scala

@@ -406,7 +406,15 @@ object Expressions {
 
         val children = if (child.isDefined) List(child.get) else Nil
         lazy val dataType = {
-            val t = if (!fieldInfo.isReverse) fieldInfo.attrInfo.dataType() else fieldInfo.reverseDataType
+            val t = {
+              if (fieldInfo.traitName != null ) {
+                typSystem.getDataType(classOf[TraitType], fieldInfo.traitName)
+              } else if (!fieldInfo.isReverse) {
+                fieldInfo.attrInfo.dataType()
+              } else {
+                fieldInfo.reverseDataType
+              }
+            }
             elemType(t)
         }
         override lazy val resolved: Boolean = true

repository/src/main/scala/org/apache/hadoop/metadata/query/GraphPersistenceStrategies.scala

@@ -67,8 +67,9 @@ trait GraphPersistenceStrategies {
     def traitNames(v: TitanVertex): java.util.List[String]
 
     def edgeLabel(fInfo: FieldInfo): String = fInfo match {
-        case FieldInfo(dataType, aInfo, null) => edgeLabel(dataType, aInfo)
-        case FieldInfo(dataType, aInfo, reverseDataType) => edgeLabel(reverseDataType, aInfo)
+        case FieldInfo(dataType, aInfo, null, null) => edgeLabel(dataType, aInfo)
+        case FieldInfo(dataType, aInfo, reverseDataType, null) => edgeLabel(reverseDataType, aInfo)
+        case FieldInfo(dataType, null, null, traitName) => traitLabel(dataType, traitName)
     }
 
     def fieldPrefixInSelect: String

repository/src/main/scala/org/apache/hadoop/metadata/query/GremlinQuery.scala

@@ -176,6 +176,16 @@ class GremlinTranslator(expr: Expression,
                 case None => step
             }
         }
+        case fe@FieldExpression(fieldName, fInfo, child)
+          if fInfo.traitName != null => {
+          val direction = "out"
+          val edgeLbl = gPersistenceBehavior.edgeLabel(fInfo)
+          val step = s"""$direction("$edgeLbl")"""
+          child match {
+            case Some(e) => s"${genQuery(e, inSelect)}.$step"
+            case None => step
+          }
+        }
         case c@ComparisonExpression(symb, f@FieldExpression(fieldName, fInfo, ch), l) => {
             ch match {
                 case Some(child) =>

repository/src/main/scala/org/apache/hadoop/metadata/query/Resolver.scala

@@ -65,6 +65,10 @@ class Resolver(srcExpr: Option[Expression] = None, aliases: Map[String, Expressi
             if (fInfo.isDefined) {
                 return new FieldExpression(fieldName, fInfo.get, Some(child))
             }
+            val tType = resolveAsTraitType(fieldName)
+            if (tType.isDefined) {
+              return new FieldExpression(fieldName, FieldInfo(child.dataType, null, null, fieldName), Some(child))
+            }
             f
         }
         case isTraitLeafExpression(traitName, classExpression)

repository/src/main/scala/org/apache/hadoop/metadata/query/TypeUtils.scala

@@ -77,10 +77,16 @@ object TypeUtils {
     }
 
     import scala.language.existentials
-    case class FieldInfo(dataType : IDataType[_], attrInfo : AttributeInfo, reverseDataType : IDataType[_] = null) {
+    case class FieldInfo(dataType : IDataType[_],
+                         attrInfo : AttributeInfo,
+                         reverseDataType : IDataType[_] = null,
+                          traitName : String = null) {
         def isReverse = reverseDataType != null
         override  def toString : String = {
-            if ( reverseDataType == null ) {
+            if ( traitName != null ) {
+              s"""FieldInfo("${dataType.getName}", "$traitName")"""
+            }
+            else if ( reverseDataType == null ) {
                 s"""FieldInfo("${dataType.getName}", "${attrInfo.name}")"""
             } else {
                 s"""FieldInfo("${dataType.getName}", "${attrInfo.name}", "${reverseDataType.getName}")"""

repository/src/test/scala/org/apache/hadoop/metadata/query/GremlinTest2.scala

+/*
+ * 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 org.apache.hadoop.metadata.query
+
+import com.thinkaurelius.titan.core.TitanGraph
+import org.apache.hadoop.metadata.query.Expressions._
+import org.apache.hadoop.metadata.typesystem.types.TypeSystem
+import org.junit.runner.RunWith
+import org.scalatest._
+import Matchers._
+import org.scalatest.junit.JUnitRunner
+
+@RunWith(classOf[JUnitRunner])
+class GremlinTest2 extends FunSuite with BeforeAndAfterAll {
+
+  var g: TitanGraph = null
+
+  override def beforeAll() {
+    TypeSystem.getInstance().reset()
+    QueryTestsUtils.setupTypes
+    g = QueryTestsUtils.setupTestGraph
+  }
+
+  override def afterAll() {
+    g.shutdown()
+  }
+
+  val STRUCT_NAME_REGEX = (TypeUtils.TEMP_STRUCT_NAME_PREFIX + "\\d+").r
+
+  def validateJson(r: GremlinQueryResult, expected: String = null): Unit = {
+    val rJ = r.toJson
+    if (expected != null) {
+      val a = STRUCT_NAME_REGEX.replaceAllIn(rJ, "")
+      val b = STRUCT_NAME_REGEX.replaceAllIn(expected, "")
+      Assertions.assert(a == b)
+    } else {
+      println(rJ)
+    }
+  }
+
+  test("testTraitSelect") {
+    val r = QueryProcessor.evaluate(_class("Table").as("t").join("Dimension").as("dim").select(id("t"), id("dim")), g)
+    validateJson(r, "{\n  \"query\":\"Table as t.Dimension as dim select t as _col_0, dim as _col_1\",\n  \"dataType\":{\n    \"typeName\":\"\",\n    \"attributeDefinitions\":[\n      {\n        \"name\":\"_col_0\",\n        \"dataTypeName\":\"Table\",\n        \"multiplicity\":{\n          \"lower\":0,\n          \"upper\":1,\n          \"isUnique\":false\n        },\n        \"isComposite\":false,\n        \"isUnique\":false,\n        \"isIndexable\":true,\n        \"reverseAttributeName\":null\n      },\n      {\n        \"name\":\"_col_1\",\n        \"dataTypeName\":\"Dimension\",\n        \"multiplicity\":{\n          \"lower\":0,\n          \"upper\":1,\n          \"isUnique\":false\n        },\n        \"isComposite\":false,\n        \"isUnique\":false,\n        \"isIndexable\":true,\n        \"reverseAttributeName\":null\n      }\n    ]\n  },\n  \"rows\":[\n    {\n      \"$typeName$\":\"\",\n      \"_col_1\":{\n        \"$typeName$\":\"Dimension\"\n      },\n      \"_col_0\":{\n        \"id\":\"3328\",\n        \"$typeName$\":\"Table\",\n        \"version\":0\n      }\n    },\n    {\n      \"$typeName$\":\"\",\n      \"_col_1\":{\n        \"$typeName$\":\"Dimension\"\n      },\n      \"_col_0\":{\n        \"id\":\"4864\",\n        \"$typeName$\":\"Table\",\n        \"version\":0\n      }\n    },\n    {\n      \"$typeName$\":\"\",\n      \"_col_1\":{\n        \"$typeName$\":\"Dimension\"\n      },\n      \"_col_0\":{\n        \"id\":\"6656\",\n        \"$typeName$\":\"Table\",\n        \"version\":0\n      }\n    }\n  ]\n}")
+  }
+
+}
\ No newline at end of file

typesystem/src/main/java/org/apache/hadoop/metadata/typesystem/types/TypeSystem.java

@@ -87,7 +87,11 @@ public class TypeSystem {
 
     public <T> T getDataType(Class<T> cls, String name) throws MetadataException {
         if (types.containsKey(name)) {
-            return cls.cast(types.get(name));
+            try {
+                return cls.cast(types.get(name));
+            } catch(ClassCastException cce) {
+                throw new MetadataException(cce);
+            }
         }
 
         /*