[~] allow ordering list properties via index

Signed-off-by: pm-osc <pm2.osc@gmail.com>

Author: pm-osc

janusgraph-backend-testutils/src/main/java/org/janusgraph/graphdb/JanusGraphIndexTest.java

@@ -4434,4 +4434,31 @@ public void testGetIndexInfo() throws DecoderException {
         assertEquals(1, indexInfo.getCompositeIndexType().getInlineFieldKeys().length);
         assertEquals("id", indexInfo.getCompositeIndexType().getInlineFieldKeys()[0]);
     }
+
+    @Test
+    public void testOrderingListProperty() {
+        PropertyKey strSingle = mgmt.makePropertyKey("strSingle").dataType(String.class).cardinality(Cardinality.SINGLE)
+                .make();
+        PropertyKey strList = mgmt.makePropertyKey("strList").dataType(String.class).cardinality(Cardinality.LIST)
+                .make();
+
+        mgmt.buildIndex("mixedStrSingle", Vertex.class).addKey(strSingle, Mapping.STRING.asParameter())
+                .buildMixedIndex(INDEX);
+        mgmt.buildIndex("mixedStrList", Vertex.class).addKey(
+                strList, Mapping.STRING.asParameter())
+                .buildMixedIndex(INDEX);
+        finishSchema();
+
+        tx.addVertex("strSingle", "val1", "strList", "val1");
+        tx.addVertex("strSingle", "val2");
+        tx.addVertex("strList", "val3");
+        tx.addVertex("strSingle", "val4", "strList", "val4", "strList", "val5", "strList", "val6");
+        tx.addVertex("strSingle", "val7", "strList", "val7");
+        tx.commit();
+
+        clopen(option(FORCE_INDEX_USAGE), false);
+
+        assertEquals(4, tx.traversal().V().has("strSingle").order().by("strSingle").count().next());
+        assertEquals(4, tx.traversal().V().has("strList").order().by("strList").count().next());
+    }
 }

janusgraph-core/src/main/java/org/janusgraph/graphdb/query/graph/GraphCentricQueryBuilder.java

@@ -15,7 +15,7 @@
 package org.janusgraph.graphdb.query.graph;
 
 import com.google.common.base.Preconditions;
-import org.janusgraph.core.Cardinality;
+//import org.janusgraph.core.Cardinality;
 import org.janusgraph.core.JanusGraphEdge;
 import org.janusgraph.core.JanusGraphElement;
 import org.janusgraph.core.JanusGraphQuery;
@@ -201,8 +201,8 @@ public GraphCentricQueryBuilder orderBy(String keyName,  org.apache.tinkerpop.gr
         Preconditions.checkArgument(key!=null && order!=null,"Need to specify and key and an order");
         Preconditions.checkArgument(Comparable.class.isAssignableFrom(key.dataType()),
                 "Can only order on keys with comparable data type. [%s] has datatype [%s]", key.name(), key.dataType());
-        Preconditions.checkArgument(key.cardinality()== Cardinality.SINGLE,
-                "Ordering is undefined on multi-valued key [%s]", key.name());
+        //Preconditions.checkArgument(key.cardinality()== Cardinality.SINGLE,
+        //        "Ordering is undefined on multi-valued key [%s]", key.name());
         Preconditions.checkArgument(!orders.containsKey(key), "orders [%s] already contains key [%s]", orders, key);
         orders.add(key, Order.convert(order));
         return this;