Allow serializing aggregations without typed keys (#316)

Author: swallez

docs/troubleshooting/index.asciidoc

@@ -7,6 +7,7 @@
 .Exceptions
 
 * <<missing-required-property>>
+* <<serialize-without-typed-keys>>
 
 
 // [[debugging]]
@@ -16,3 +17,4 @@
 // === Elasticsearch deprecation warnings
 
 include::missing-required-property.asciidoc[]
+include::serialize-without-typed-keys.asciidoc[]

docs/troubleshooting/serialize-without-typed-keys.asciidoc

@@ -0,0 +1,24 @@
+[[serialize-without-typed-keys]]
+=== Serializing aggregations and suggestions without typed keys
+
+{es} search requests accept a `typed_key` parameter that allow returning type information along with the name in aggregation and suggestion results (see the {es-docs}/search-aggregations.html#return-agg-type[aggregations documentation] for additional details).
+
+The {java-client} always adds this parameter to search requests, as type information is needed to know the concrete class that should be used to deserialize aggregation and suggestion results.
+
+Symmetrically, the {java-client} also serializes aggregation and suggestion results using this `typed_keys` format, so that it can correctly deserialize the results of its own serialization.
+
+["source","java"]
+--------------------------------------------------
+ElasticsearchClient esClient = ...
+include-tagged::{doc-tests-src}/troubleshooting/TroubleShootingTests.java[aggregation-typed-keys]
+--------------------------------------------------
+
+However, in some use cases serializing objects in the `typed_keys` format may not be desirable, for example when the {java-client} is used in an application that acts as a front-end to other services that expect the default format for aggregations and suggestions.
+
+You can disable `typed_keys` serialization by setting the `JsonpMapperFeatures.SERIALIZE_TYPED_KEYS` attribute to `false` on your mapper object:
+
+["source","java"]
+--------------------------------------------------
+ElasticsearchClient esClient = ...
+include-tagged::{doc-tests-src}/troubleshooting/TroubleShootingTests.java[aggregation-no-typed-keys]
+--------------------------------------------------

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

@@ -153,7 +153,10 @@ public void deserializeEntry(String key, JsonParser parser, JsonpMapper mapper,
     }
 
     /**
-     * Serialize an externally tagged union using the typed keys encoding.
+     * Serialize a map of externally tagged union objects.
+     * <p>
+     * If {@link JsonpMapperFeatures#SERIALIZE_TYPED_KEYS} is <code>true</code> (the default), the typed keys encoding
+     * (<code>type#name</code>) is used.
      */
     static <T extends JsonpSerializable & TaggedUnion<? extends JsonEnum, ?>> void serializeTypedKeys(
         Map<String, T> map, JsonGenerator generator, JsonpMapper mapper
@@ -163,36 +166,65 @@ public void deserializeEntry(String key, JsonParser parser, JsonpMapper mapper,
         generator.writeEnd();
     }
 
+    /**
+     * Serialize a map of externally tagged union object arrays.
+     * <p>
+     * If {@link JsonpMapperFeatures#SERIALIZE_TYPED_KEYS} is <code>true</code> (the default), the typed keys encoding
+     * (<code>type#name</code>) is used.
+     */
     static <T extends JsonpSerializable & TaggedUnion<? extends JsonEnum, ?>> void serializeTypedKeysArray(
         Map<String, List<T>> map, JsonGenerator generator, JsonpMapper mapper
     ) {
         generator.writeStartObject();
-        for (Map.Entry<String, List<T>> entry: map.entrySet()) {
-            List<T> list = entry.getValue();
-            if (list.isEmpty()) {
-                continue; // We can't know the kind, skip this entry
-            }
 
-            generator.writeKey(list.get(0)._kind().jsonValue() + "#" + entry.getKey());
-            generator.writeStartArray();
-            for (T value: list) {
-                value.serialize(generator, mapper);
+        if (mapper.attribute(JsonpMapperFeatures.SERIALIZE_TYPED_KEYS, true)) {
+            for (Map.Entry<String, List<T>> entry: map.entrySet()) {
+                List<T> list = entry.getValue();
+                if (list.isEmpty()) {
+                    continue; // We can't know the kind, skip this entry
+                }
+
+                generator.writeKey(list.get(0)._kind().jsonValue() + "#" + entry.getKey());
+                generator.writeStartArray();
+                for (T value: list) {
+                    value.serialize(generator, mapper);
+                }
+                generator.writeEnd();
+            }
+        } else {
+            for (Map.Entry<String, List<T>> entry: map.entrySet()) {
+                generator.writeKey(entry.getKey());
+                generator.writeStartArray();
+                for (T value: entry.getValue()) {
+                    value.serialize(generator, mapper);
+                }
+                generator.writeEnd();
             }
-            generator.writeEnd();
         }
+
         generator.writeEnd();
     }
 
     /**
-     * Serialize an externally tagged union using the typed keys encoding, without the enclosing start/end object.
+     * Serialize a map of externally tagged union objects, without the enclosing start/end object.
+     * <p>
+     * If {@link JsonpMapperFeatures#SERIALIZE_TYPED_KEYS} is <code>true</code> (the default), the typed keys encoding
+     * (<code>type#name</code>) is used.
      */
     static <T extends JsonpSerializable & TaggedUnion<? extends JsonEnum, ?>> void serializeTypedKeysInner(
         Map<String, T> map, JsonGenerator generator, JsonpMapper mapper
     ) {
-        for (Map.Entry<String, T> entry: map.entrySet()) {
-            T value = entry.getValue();
-            generator.writeKey(value._kind().jsonValue() + "#" + entry.getKey());
-            value.serialize(generator, mapper);
+        if (mapper.attribute(JsonpMapperFeatures.SERIALIZE_TYPED_KEYS, true)) {
+            for (Map.Entry<String, T> entry: map.entrySet()) {
+                T value = entry.getValue();
+                generator.writeKey(value._kind().jsonValue() + "#" + entry.getKey());
+                value.serialize(generator, mapper);
+            }
+        } else {
+            for (Map.Entry<String, T> entry: map.entrySet()) {
+                generator.writeKey(entry.getKey());
+                entry.getValue().serialize(generator, mapper);
+            }
         }
     }
 }

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

@@ -77,9 +77,12 @@ default <T> T attribute(String name, T defaultValue) {
     }
 
     /**
-     * Create a new mapper with a named attribute that delegates to this one.
+     * Create a new mapper with an additional attribute.
+     * <p>
+     * The {@link JsonpMapperFeatures} class contains the names of attributes that all implementations of
+     * <code>JsonpMapper</code> must implement.
+     *
+     * @see JsonpMapperFeatures
      */
-    default <T> JsonpMapper withAttribute(String name, T value) {
-        return new AttributedJsonpMapper(this, name, value);
-    }
+    <T> JsonpMapper withAttribute(String name, T value);
 }

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

@@ -25,12 +25,41 @@
 
 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
 
 public abstract class JsonpMapperBase implements JsonpMapper {
 
     /** Get a serializer when none of the builtin ones are applicable */
     protected abstract <T> JsonpDeserializer<T> getDefaultDeserializer(Class<T> clazz);
 
+    private Map<String, Object> attributes;
+
+    @Nullable
+    @Override
+    @SuppressWarnings("unchecked")
+    public <T> T attribute(String name) {
+        return attributes == null ? null : (T)attributes.get(name);
+    }
+
+    /**
+     * Updates attributes to a copy of the current ones with an additional key/value pair.
+     *
+     * Mutates the current mapper, intended to be used in implementations of {@link #withAttribute(String, Object)}
+     */
+    protected JsonpMapperBase addAttribute(String name, Object value) {
+        if (attributes == null) {
+            this.attributes = Collections.singletonMap(name, value);
+        } else {
+            Map<String, Object> newAttrs = new HashMap<>(attributes.size() + 1);
+            newAttrs.putAll(attributes);
+            newAttrs.put(name, value);
+            this.attributes = newAttrs;
+        }
+        return this;
+    }
+
     @Override
     public <T> T deserialize(JsonParser parser, Class<T> clazz) {
         JsonpDeserializer<T> deserializer = findDeserializer(clazz);

java-client/src/main/java/co/elastic/clients/json/AttributedJsonpMapper.java renamed to java-client/src/main/java/co/elastic/clients/json/JsonpMapperFeatures.java

@@ -19,27 +19,11 @@
 
 package co.elastic.clients.json;
 
-import javax.annotation.Nullable;
-
-class AttributedJsonpMapper extends DelegatingJsonpMapper {
-
-    private final String name;
-    private final Object value;
+/**
+ * Defines attribute names for {@link JsonpMapper} features.
+ */
+public class JsonpMapperFeatures {
 
-    AttributedJsonpMapper(JsonpMapper mapper, String name, Object value) {
-        super(mapper);
-        this.name = name;
-        this.value = value;
-    }
+    public static final String SERIALIZE_TYPED_KEYS = JsonpMapperFeatures.class.getName() + ":SERIALIZE_TYPED_KEYS";
 
-    @Override
-    @Nullable
-    @SuppressWarnings("unchecked")
-    public <T> T attribute(String name) {
-        if (this.name.equals(name)) {
-            return (T)this.value;
-        } else {
-            return mapper.attribute(name);
-        }
-    }
 }

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

@@ -77,6 +77,11 @@ public SimpleJsonpMapper() {
         this(true);
     }
 
+    @Override
+    public <T> JsonpMapper withAttribute(String name, T value) {
+        return new SimpleJsonpMapper(this.ignoreUnknownFields).addAttribute(name, value);
+    }
+
     @Override
     public boolean ignoreUnknownFields() {
         return ignoreUnknownFields;

java-client/src/main/java/co/elastic/clients/json/jackson/JacksonJsonpMapper.java

@@ -39,18 +39,30 @@ public class JacksonJsonpMapper extends JsonpMapperBase {
     private final JacksonJsonProvider provider;
     private final ObjectMapper objectMapper;
 
+    private JacksonJsonpMapper(ObjectMapper objectMapper, JacksonJsonProvider provider) {
+        this.objectMapper = objectMapper;
+        this.provider = provider;
+    }
+
     public JacksonJsonpMapper(ObjectMapper objectMapper) {
-        this.objectMapper = objectMapper
-            .configure(SerializationFeature.INDENT_OUTPUT, false)
-            .setSerializationInclusion(JsonInclude.Include.NON_NULL);
-        // Creating the json factory from the mapper ensures it will be returned by JsonParser.getCodec()
-        this.provider = new JacksonJsonProvider(this.objectMapper.getFactory());
+        this(
+            objectMapper
+                .configure(SerializationFeature.INDENT_OUTPUT, false)
+                .setSerializationInclusion(JsonInclude.Include.NON_NULL),
+            // Creating the json factory from the mapper ensures it will be returned by JsonParser.getCodec()
+            new JacksonJsonProvider(objectMapper.getFactory())
+        );
     }
 
     public JacksonJsonpMapper() {
         this(new ObjectMapper());
     }
 
+    @Override
+    public <T> JsonpMapper withAttribute(String name, T value) {
+        return new JacksonJsonpMapper(this.objectMapper, this.provider).addAttribute(name, value);
+    }
+
     /**
      * Returns the underlying Jackson mapper.
      */

java-client/src/main/java/co/elastic/clients/json/jsonb/JsonbJsonpMapper.java

@@ -54,6 +54,11 @@ public JsonbJsonpMapper() {
         this(JsonpUtils.provider(), JsonbProvider.provider());
     }
 
+    @Override
+    public <T> JsonpMapper withAttribute(String name, T value) {
+        return new JsonbJsonpMapper(this.jsonProvider, this.jsonb).addAttribute(name, value);
+    }
+
     @Override
     protected <T> JsonpDeserializer<T> getDefaultDeserializer(Class<T> clazz) {
         return new Deserializer<>(clazz);

java-client/src/main/java/co/elastic/clients/util/WithJsonObjectBuilderBase.java

@@ -47,22 +47,33 @@ public B withJson(JsonParser parser, JsonpMapper mapper) {
         }
 
         // Generic parameters are always deserialized to JsonData unless the parent mapper can provide a deserializer
-        mapper = new DelegatingJsonpMapper(mapper) {
-            @Override
-            public <T> T attribute(String name) {
-                T attr = mapper.attribute(name);
-                if (attr == null && name.startsWith("co.elastic.clients:Deserializer")) {
-                    @SuppressWarnings("unchecked")
-                    T result = (T)JsonData._DESERIALIZER;
-                    return result;
-                } else {
-                    return attr;
-                }
-            }
-        };
+        mapper = new WithJsonMapper(mapper);
 
         @SuppressWarnings("unchecked")
         ObjectDeserializer<B> builderDeser = (ObjectDeserializer<B>) DelegatingDeserializer.unwrap(classDeser);
         return builderDeser.deserialize(self(), parser, mapper, parser.next());
     }
+
+    private static class WithJsonMapper extends DelegatingJsonpMapper {
+        WithJsonMapper(JsonpMapper parent) {
+            super(parent);
+        }
+
+        @Override
+        public <T> T attribute(String name) {
+            T attr = mapper.attribute(name);
+            if (attr == null && name.startsWith("co.elastic.clients:Deserializer")) {
+                @SuppressWarnings("unchecked")
+                T result = (T)JsonData._DESERIALIZER;
+                return result;
+            } else {
+                return attr;
+            }
+        }
+
+        @Override
+        public <T> JsonpMapper withAttribute(String name, T value) {
+            return new WithJsonMapper(this.mapper.withAttribute(name, value));
+        }
+    }
 }