SCRIPTING: Support BucketAggScript return null

modules/lang-expression/src/main/java/org/elasticsearch/script/expression/ExpressionScriptEngine.java

@@ -147,7 +147,7 @@ private static BucketAggregationScript.Factory newBucketAggregationScriptFactory
  }
  return new BucketAggregationScript(parameters) {
  @Override
- public double execute() {
+ public Double execute() {
  getParams().forEach((name, value) -> {
  ReplaceableConstDoubleValues placeholder = functionValuesMap.get(name);
  if (placeholder == null) {

server/src/main/java/org/elasticsearch/script/BucketAggregationScript.java

@@ -46,7 +46,7 @@ public Map<String, Object> getParams() {
  return params;
  }
 
- public abstract double execute();
+ public abstract Double execute();
 
  public interface Factory {
  BucketAggregationScript newInstance(Map<String, Object> params);

server/src/main/java/org/elasticsearch/search/aggregations/pipeline/bucketscript/BucketScriptPipelineAggregator.java

@@ -110,13 +110,17 @@ public InternalAggregation reduce(InternalAggregation aggregation, ReduceContext
  if (skipBucket) {
  newBuckets.add(bucket);
  } else {
- double returned = factory.newInstance(vars).execute();
- final List<InternalAggregation> aggs = StreamSupport.stream(bucket.getAggregations().spliterator(), false).map(
+ Double returned = factory.newInstance(vars).execute();
+ if (returned == null) {
+ newBuckets.add(bucket);
+ } else {
+ final List<InternalAggregation> aggs = StreamSupport.stream(bucket.getAggregations().spliterator(), false).map(
  (p) -> (InternalAggregation) p).collect(Collectors.toList());
- aggs.add(new InternalSimpleValue(name(), returned, formatter, new ArrayList<>(), metaData()));
- InternalMultiBucketAggregation.InternalBucket newBucket = originalAgg.createBucket(new InternalAggregations(aggs),
+  aggs.add(new InternalSimpleValue(name(), returned, formatter, new ArrayList<>(), metaData()));
+  InternalMultiBucketAggregation.InternalBucket newBucket = originalAgg.createBucket(new InternalAggregations(aggs),
  bucket);
- newBuckets.add(newBucket);
+ newBuckets.add(newBucket);
+ }
  }
  }
  return originalAgg.create(newBuckets);

server/src/test/java/org/elasticsearch/search/aggregations/pipeline/BucketScriptIT.java

@@ -117,6 +117,8 @@ protected Map<String, Function<Map<String, Object>, Object>> pluginScripts() {
  return value0 + value1 + value2;
  });
 
+ scripts.put("return null", vars -> null);
+
  return scripts;
  }
  }
@@ -478,6 +480,33 @@ public void testInlineScriptInsertZeros() {
  }
  }
 
+ public void testInlineScriptReturnNull() {
+ SearchResponse response = client()
+ .prepareSearch("idx")
+ .addAggregation(
+ histogram("histo")
+ .field(FIELD_1_NAME).interval(interval)
+ .subAggregation(
+ bucketScript(
+ "nullField",
+ new Script(ScriptType.INLINE, CustomScriptPlugin.NAME, "return null", Collections.emptyMap())
+ )
+ )
+ ).execute().actionGet();
+
+ assertSearchResponse(response);
+
+ Histogram histo = response.getAggregations().get("histo");
+ assertThat(histo, notNullValue());
+ assertThat(histo.getName(), equalTo("histo"));
+ List<? extends Histogram.Bucket> buckets = histo.getBuckets();
+
+ for (int i = 0; i < buckets.size(); ++i) {
+ Histogram.Bucket bucket = buckets.get(i);
+ assertNull(bucket.getAggregations().get("nullField"));
+ }
+ }
+
  public void testStoredScript() {
  assertAcked(client().admin().cluster().preparePutStoredScript()
  .setId("my_script")

test/framework/src/main/java/org/elasticsearch/script/MockScriptEngine.java

@@ -111,8 +111,13 @@ public void execute(Map<String, Object> ctx) {
  } else if (context.instanceClazz.equals(BucketAggregationScript.class)) {
  BucketAggregationScript.Factory factory = parameters -> new BucketAggregationScript(parameters) {
  @Override
- public double execute() {
- return ((Number) script.apply(getParams())).doubleValue();
+ public Double execute() {
+ Object ret = script.apply(getParams());
+ if (ret == null) {
+ return null;
+ } else {
+ return ((Number) ret).doubleValue();
+ }
  }
  };
  return context.factoryClazz.cast(factory);