From 83c26eb74abe7d3c4550a927ee78fe3ee4010d49 Mon Sep 17 00:00:00 2001
From: David Pilato <david@pilato.fr>
Date: Sat, 10 Aug 2013 19:09:19 +0200
Subject: [PATCH] NPE for POST mode facets if facet_filter gives no document.
 Closes #3479.

---
 .../search/facet/FacetExecutor.java           | 12 ++++++----
 .../search/facet/SimpleFacetsTests.java       | 24 ++++++++++++++++++-
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/src/main/java/org/elasticsearch/search/facet/FacetExecutor.java b/src/main/java/org/elasticsearch/search/facet/FacetExecutor.java
index 05c0179423c..fc2571e0918 100644
--- a/src/main/java/org/elasticsearch/search/facet/FacetExecutor.java
+++ b/src/main/java/org/elasticsearch/search/facet/FacetExecutor.java
@@ -66,11 +66,13 @@ public abstract class FacetExecutor {
                 for (int i = 0; i < docSets.size(); i++) {
                     ContextDocIdSet entry = docSets.get(i);
                     DocIdSet filteredSet = filter.getDocIdSet(entry.context, null);
-                    filteredEntries.add(new ContextDocIdSet(
-                            entry.context,
-                            // TODO: can we be smart here, maybe AndDocIdSet is not always fastest?
-                            new AndDocIdSet(new DocIdSet[]{entry.docSet, filteredSet})
-                    ));
+                    if (filteredSet != null) {
+                        filteredEntries.add(new ContextDocIdSet(
+                                entry.context,
+                                // TODO: can we be smart here, maybe AndDocIdSet is not always fastest?
+                                new AndDocIdSet(new DocIdSet[]{entry.docSet, filteredSet})
+                        ));
+                    }
                 }
                 post.executePost(filteredEntries);
             }
diff --git a/src/test/java/org/elasticsearch/test/integration/search/facet/SimpleFacetsTests.java b/src/test/java/org/elasticsearch/test/integration/search/facet/SimpleFacetsTests.java
index 0a1f2212c67..67fae4c7c6f 100644
--- a/src/test/java/org/elasticsearch/test/integration/search/facet/SimpleFacetsTests.java
+++ b/src/test/java/org/elasticsearch/test/integration/search/facet/SimpleFacetsTests.java
@@ -58,7 +58,6 @@ import static org.elasticsearch.common.xcontent.XContentFactory.jsonBuilder;
 import static org.elasticsearch.index.query.FilterBuilders.termFilter;
 import static org.elasticsearch.index.query.QueryBuilders.*;
 import static org.elasticsearch.search.facet.FacetBuilders.*;
-import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.*;
 
 /**
@@ -2282,6 +2281,29 @@ public class SimpleFacetsTests extends AbstractSharedClusterTest {
         }
     }
 
+    @Test // #3479: Null pointer exception for POST mode facets if facet_filter accepts no documents
+    public void testFilterFacetWithFacetFilterPostMode() throws IOException {
+        client().prepareIndex("test", "type1").setSource(jsonBuilder().startObject()
+                .field("field", "xxx")
+                .endObject()).execute().actionGet();
+
+        client().admin().indices().prepareRefresh().execute().actionGet();
+
+        for (int i = 0; i < numberOfRuns(); i++) {
+            SearchResponse searchResponse = client().prepareSearch()
+                    .setQuery(matchAllQuery())
+                    .addFacet(
+                            termsFacet("facet1").field("field").mode(FacetBuilder.Mode.POST).facetFilter(termFilter("tag", "doesnotexist"))
+                    )
+                    .execute().actionGet();
+
+            assertThat(searchResponse.getFailedShards(), equalTo(0));
+            TermsFacet facet = searchResponse.getFacets().facet("facet1");
+            assertThat(facet.getName(), equalTo("facet1"));
+            assertThat(facet.getEntries().size(), equalTo(0));
+        }
+    }
+
     private long utcTimeInMillis(String time) {
         return timeInMillis(time, DateTimeZone.UTC);
     }