AMBARI-21706 : Fix exception messages whenever empty host list is passed in predicate. (avijayan)

ambari-server/src/main/java/org/apache/ambari/server/api/predicate/QueryParser.java

@@ -107,7 +107,9 @@ public class QueryParser {
         if (keyObject != null) {
           String key = keyObject.toString();
           if (key.endsWith("/host_name")) {
-            expression.setRightOperand(expression.getRightOperand().toString().toLowerCase());
+            if (expression.getRightOperand() != null) {
+              expression.setRightOperand(expression.getRightOperand().toString().toLowerCase());
+            }
           }
         }
       }

ambari-server/src/main/java/org/apache/ambari/server/api/predicate/operators/InOperator.java

@@ -47,7 +47,7 @@ public class InOperator extends AbstractOperator implements RelationalOperator {
   public Predicate toPredicate(String prop, String val) throws InvalidQueryException {
 
     if (val == null) {
-      throw new InvalidQueryException("IN operator is missing a required right operand.");
+      throw new InvalidQueryException("IN operator is missing a required right operand for property " + prop);
     }
 
     String[] tokens = val.split(",");

ambari-server/src/main/java/org/apache/ambari/server/controller/internal/StackAdvisorResourceProvider.java

@@ -21,6 +21,7 @@ package org.apache.ambari.server.controller.internal;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
@@ -106,8 +107,22 @@ public abstract class StackAdvisorResourceProvider extends ReadOnlyResourceProvi
        * 
        * @see JsonRequestBodyParser for arrays parsing
        */
-      List<String> hosts = (List<String>) getRequestProperty(request, HOST_PROPERTY);
-      List<String> services = (List<String>) getRequestProperty(request, SERVICES_PROPERTY);
+      Object hostsObject = getRequestProperty(request, HOST_PROPERTY);
+      if (hostsObject instanceof LinkedHashSet) {
+        if (((LinkedHashSet)hostsObject).isEmpty()) {
+          throw new Exception("Empty host list passed to recommendation service");
+        }
+      }
+      List<String> hosts = (List<String>) hostsObject;
+
+      Object servicesObject = getRequestProperty(request, SERVICES_PROPERTY);
+      if (servicesObject instanceof LinkedHashSet) {
+        if (((LinkedHashSet)servicesObject).isEmpty()) {
+          throw new Exception("Empty service list passed to recommendation service");
+        }
+      }
+      List<String> services = (List<String>) servicesObject;
+
       Map<String, Set<String>> hgComponentsMap = calculateHostGroupComponentsMap(request);
       Map<String, Set<String>> hgHostsMap = calculateHostGroupHostsMap(request);
       Map<String, Set<String>> componentHostsMap = calculateComponentHostsMap(hgComponentsMap,
@@ -133,7 +148,6 @@ public abstract class StackAdvisorResourceProvider extends ReadOnlyResourceProvi
       LOG.warn("Error occurred during preparation of stack advisor request", e);
       Response response = Response.status(Status.BAD_REQUEST)
           .entity(String.format("Request body is not correct, error: %s", e.getMessage())).build();
-      // TODO: Hosts and services must not be empty
       throw new WebApplicationException(response);
     }
   }

ambari-server/src/test/java/org/apache/ambari/server/api/predicate/QueryParserTest.java

@@ -36,6 +36,7 @@ import org.apache.ambari.server.controller.predicate.LessPredicate;
 import org.apache.ambari.server.controller.predicate.NotPredicate;
 import org.apache.ambari.server.controller.predicate.OrPredicate;
 import org.apache.ambari.server.controller.spi.Predicate;
+import org.junit.Assert;
 import org.junit.Test;
 
 /**
@@ -204,6 +205,23 @@ public class QueryParserTest {
     assertEquals(orPredicate, p);
   }
 
+  @Test
+  public void testParse_InOp__HostName_Empty() throws Exception {
+    List<Token> listTokens = new ArrayList<Token>();
+    // foo.in(one,two,3)
+    listTokens.add(new Token(Token.TYPE.RELATIONAL_OPERATOR_FUNC, ".in("));
+    listTokens.add(new Token(Token.TYPE.PROPERTY_OPERAND, "Hosts/host_name"));
+    listTokens.add(new Token(Token.TYPE.BRACKET_CLOSE, ")"));
+
+    QueryParser parser = new QueryParser();
+    try {
+      Predicate p = parser.parse(listTokens.toArray(new Token[listTokens.size()]));
+      Assert.fail();
+    } catch (InvalidQueryException e) {
+      Assert.assertEquals(e.getMessage(), "IN operator is missing a required right operand for property Hosts/host_name");
+    }
+  }
+
   @Test
   public void testParse_EquOp_HostName() throws Exception {
     List<Token> listTokens = new ArrayList<>();

ambari-server/src/test/java/org/apache/ambari/server/controller/internal/StackAdvisorResourceProviderTest.java

@@ -31,6 +31,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -38,6 +39,7 @@ import java.util.Set;
 import org.apache.ambari.server.controller.AmbariManagementController;
 import org.apache.ambari.server.controller.spi.Request;
 import org.apache.ambari.server.controller.spi.Resource;
+import org.junit.Assert;
 import org.junit.Test;
 
 public class StackAdvisorResourceProviderTest {
@@ -145,4 +147,27 @@ public class StackAdvisorResourceProviderTest {
     assertFalse(properties.containsKey("string_prop"));
 
   }
+
+  @Test
+  public void testStackAdvisorWithEmptyHosts() {
+    Map<Resource.Type, String> keyPropertyIds = Collections.emptyMap();
+    Set<String> propertyIds = Collections.emptySet();
+    AmbariManagementController ambariManagementController = mock(AmbariManagementController.class);
+    RecommendationResourceProvider provider = new RecommendationResourceProvider(propertyIds,
+      keyPropertyIds, ambariManagementController);
+
+    Request request = mock(Request.class);
+    Set<Map<String, Object>> propertiesSet = new HashSet<Map<String, Object>>();
+    Map<String, Object> propertiesMap = new HashMap<String, Object>();
+    propertiesMap.put("hosts", new LinkedHashSet<>());
+    propertiesMap.put("recommend", "configurations");
+    propertiesSet.add(propertiesMap);
+    doReturn(propertiesSet).when(request).getProperties();
+
+    try {
+      provider.createResources(request);
+      Assert.fail();
+    } catch (Exception e) {
+    }
+  }
 }