Add serializeToString() method

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

@@ -48,6 +48,11 @@ public <T> void serialize(T value, JsonGenerator generator) {
         mapper.serialize(value, generator);
     }
 
+    @Override
+    public <T> String serializeToString(T value) {
+        return mapper.serializeToString(value);
+    }
+
     @Override
     public boolean ignoreUnknownFields() {
         return mapper.ignoreUnknownFields();

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

@@ -19,11 +19,14 @@
 
 package co.elastic.clients.json;
 
+import co.elastic.clients.json.jackson.JacksonJsonProvider;
+import co.elastic.clients.json.jackson.JacksonJsonpMapper;
 import jakarta.json.spi.JsonProvider;
 import jakarta.json.stream.JsonGenerator;
 import jakarta.json.stream.JsonParser;
 
 import javax.annotation.Nullable;
+import java.io.StringWriter;
 
 /**
  * A {@code JsonpMapper} combines a JSON-P provider and object serialization/deserialization based on JSON-P events.
@@ -51,6 +54,17 @@ public interface JsonpMapper {
      */
     <T> void serialize(T value, JsonGenerator generator);
 
+    /**
+     * Serialize an object to its JSON String representation
+     */
+    default <T> String serializeToString(T value) {
+        StringWriter writer = new StringWriter();
+        try (JsonGenerator generator = jsonProvider().createGenerator(writer)) {
+            serialize(value, generator);
+        };
+        return writer.toString();
+    }
+
     /**
      * Should object parsers in the API client be lenient and silently ignore unknown fields?
      *

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

@@ -19,11 +19,15 @@
 
 package co.elastic.clients.json;
 
+import jakarta.json.JsonException;
 import jakarta.json.JsonValue;
+import jakarta.json.spi.JsonProvider;
 import jakarta.json.stream.JsonGenerator;
 import jakarta.json.stream.JsonParser;
 
 import javax.annotation.Nullable;
+import java.io.IOException;
+import java.io.StringWriter;
 import java.lang.reflect.Field;
 
 public abstract class JsonpMapperBase implements JsonpMapper {
@@ -76,6 +80,24 @@ public static <T> JsonpSerializer<T> findSerializer(T value) {
         return null;
     }
 
+    @Override
+    public <T> String serializeToString(T value) {
+        JsonpSerializer<T> serializer = findSerializer(value);
+
+        if (serializer != null) {
+            StringWriter writer = new StringWriter();
+            JsonGenerator generator = jsonProvider().createGenerator(writer);
+            serializer.serialize(value, generator, this);
+            generator.close();
+            return writer.toString();
+        } else {
+            throw new JsonException(
+                    "Cannot find a serializer for type " + value.getClass().getName() +
+                            ". Consider using a full-featured JsonpMapper"
+            );
+        }
+    }
+
     protected static class JsonpSerializableSerializer<T extends JsonpSerializable> implements JsonpSerializer<T> {
         @Override
         public void serialize(T value, JsonGenerator generator, JsonpMapper mapper) {

java-client/src/test/java/co/elastic/clients/elasticsearch/json/JsonDataTest.java

@@ -20,6 +20,10 @@
 package co.elastic.clients.elasticsearch.json;
 
 import co.elastic.clients.elasticsearch.ElasticsearchClient;
+import co.elastic.clients.elasticsearch._types.Result;
+import co.elastic.clients.elasticsearch.core.IndexResponse;
+import co.elastic.clients.elasticsearch.core.SearchResponse;
+import co.elastic.clients.elasticsearch.core.search.TotalHitsRelation;
 import co.elastic.clients.elasticsearch.indices.CreateIndexRequest;
 import co.elastic.clients.json.DelegatingDeserializer;
 import co.elastic.clients.json.JsonData;
@@ -40,6 +44,7 @@
 import java.io.Reader;
 import java.io.StringReader;
 import java.io.StringWriter;
+import java.util.Collections;
 
 public class JsonDataTest extends Assert {
 
@@ -125,4 +130,38 @@ public void testConvert() {
         assertEquals(JsonValue.ValueType.STRING, value.getValueType());
         assertEquals("foo", ((JsonString)value).getString());
     }
+
+    @Test
+    public void testIndexResponse() {
+        IndexResponse resp = IndexResponse.of(r -> r
+                .index("foo")
+                .id("1")
+                .primaryTerm(1)
+                .seqNo(1)
+                .version(1)
+                .shards(s -> s.successful(1).failed(0).total(1))
+                .result(Result.Created)
+        );
+
+        String json = new JacksonJsonpMapper().serializeToString(resp);
+
+        assertEquals("{\"_id\":\"1\",\"_index\":\"foo\",\"_primary_term\":1,\"result\":\"created\",\"_seq_no\":1,\"_shards\":{\"failed\":0.0,\"successful\":1.0,\"total\":1.0},\"_version\":1}", json);
+    }
+
+    @Test
+    public void testSearchResponse() {
+        SearchResponse<?> resp = SearchResponse.searchResponseOf(r -> r
+                .took(10)
+                .shards(s -> s.successful(1).failed(0).total(1))
+                .timedOut(false)
+                .hits(h -> h
+                        .total(t -> t.value(0).relation(TotalHitsRelation.Eq))
+                        .hits(Collections.emptyList())
+                )
+        );
+
+        String json = new JacksonJsonpMapper().serializeToString(resp);
+
+        assertEquals("{\"took\":10,\"timed_out\":false,\"_shards\":{\"failed\":0.0,\"successful\":1.0,\"total\":1.0},\"hits\":{\"total\":{\"relation\":\"eq\",\"value\":0},\"hits\":[]}}", json);
+    }
 }