Accept null values in arrays (#68)

Author: swallez

java-client/src/main/java/co/elastic/clients/json/JsonpDeserializerBase.java

@@ -312,8 +312,13 @@ public List<T> deserialize(JsonParser parser, JsonpMapper mapper, Event event) {
             if (event == Event.START_ARRAY) {
                 List<T> result = new ArrayList<>();
                 while ((event = parser.next()) != Event.END_ARRAY) {
-                    JsonpUtils.ensureAccepts(itemDeserializer, parser, event);
-                    result.add(itemDeserializer.deserialize(parser, mapper, event));
+                    // JSON null: add null unless the deserializer can handle it
+                    if (event == Event.VALUE_NULL && !itemDeserializer.accepts(event)) {
+                        result.add(null);
+                    } else {
+                        JsonpUtils.ensureAccepts(itemDeserializer, parser, event);
+                        result.add(itemDeserializer.deserialize(parser, mapper, event));
+                    }
                 }
                 return result;
             } else {

java-client/src/test/java/co/elastic/clients/elasticsearch/model/BuiltinTypesTest.java

@@ -27,8 +27,11 @@
 import co.elastic.clients.elasticsearch._types.query_dsl.SpanGapQuery;
 import co.elastic.clients.elasticsearch.core.SearchRequest;
 import co.elastic.clients.elasticsearch.indices.IndexSettings;
+import co.elastic.clients.json.JsonpDeserializer;
+import jakarta.json.stream.JsonParser;
 import org.junit.Test;
 
+import java.io.StringReader;
 import java.util.List;
 
 public class BuiltinTypesTest extends ModelTestCase {
@@ -50,6 +53,38 @@ public void testLenientArray() {
         assertGetterType(List.class, SearchRequest.class, "index");
     }
 
+    @Test
+    public void testNullArrayItem() {
+        // See https://github.com/elastic/elasticsearch-java/issues/66
+
+        String json = "[\"a\", null, \"c\"]";
+
+        // Types that don't accept null events should end up as null values in the list
+        {
+            JsonpDeserializer<String> stringDeser = JsonpDeserializer.stringDeserializer();
+            assertFalse(stringDeser.accepts(JsonParser.Event.VALUE_NULL));
+
+            JsonParser parser = mapper.jsonProvider().createParser(new StringReader(json));
+
+            List<String> stringList = JsonpDeserializer.arrayDeserializer(stringDeser).deserialize(parser, mapper);
+            assertEquals("a", stringList.get(0));
+            assertNull(stringList.get(1));
+            assertEquals("c", stringList.get(2));
+        }
+
+        // Types that do accept null events should end up as their null representation
+        {
+            assertTrue(FieldValue._DESERIALIZER.accepts(JsonParser.Event.VALUE_NULL));
+
+            JsonParser parser = mapper.jsonProvider().createParser(new StringReader(json));
+            List<FieldValue> valueList = JsonpDeserializer.arrayDeserializer(FieldValue._DESERIALIZER).deserialize(parser, mapper);
+
+            assertEquals("a", valueList.get(0)._get());
+            assertTrue(valueList.get(1).isNull());
+            assertEquals("c", valueList.get(2)._get());
+        }
+    }
+
     @Test
     public void testSpanGapQuery() {
         // Hand-written class