fix: register custom type adapter factory for Dynamic vector index

Author: bevzzz

src/main/java/io/weaviate/client6/v1/api/collections/VectorConfig.java

@@ -285,7 +285,7 @@ public void write(JsonWriter out, VectorConfig value) throws IOException {
           vectorizer.add(value._kind().jsonValue(), config);
           vectorIndex.getAsJsonObject().add("vectorizer", vectorizer);
 
-          if (value.quantization() != null) {
+          if (value.quantization() != null && !config.getAsJsonObject().get("quantization").isJsonNull()) {
             vectorIndex.getAsJsonObject()
                 .get("vectorIndexConfig").getAsJsonObject()
                 .add(value.quantization()._kind().jsonValue(), config.getAsJsonObject().remove("quantization"));

src/main/java/io/weaviate/client6/v1/api/collections/vectorindex/Dynamic.java

@@ -1,8 +1,18 @@
 package io.weaviate.client6.v1.api.collections.vectorindex;
 
+import java.io.IOException;
 import java.util.function.Function;
 
+import com.google.gson.Gson;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
 import com.google.gson.annotations.SerializedName;
+import com.google.gson.internal.Streams;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
 
 import io.weaviate.client6.v1.api.collections.VectorIndex;
 import io.weaviate.client6.v1.internal.ObjectBuilder;
@@ -64,4 +74,47 @@ public Dynamic build() {
       return new Dynamic(this);
     }
   }
+
+  public static enum CustomTypeAdapterFactory implements TypeAdapterFactory {
+    INSTANCE;
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+      var rawType = type.getRawType();
+      if (!Dynamic.class.isAssignableFrom(rawType)) {
+        return null;
+      }
+
+      final var hnswAdapter = gson.getDelegateAdapter(VectorIndex.CustomTypeAdapterFactory.INSTANCE,
+          TypeToken.get(Hnsw.class));
+      final var flatAdapter = gson.getDelegateAdapter(VectorIndex.CustomTypeAdapterFactory.INSTANCE,
+          TypeToken.get(Flat.class));
+
+      return (TypeAdapter<T>) new TypeAdapter<Dynamic>() {
+
+        @Override
+        public void write(JsonWriter out, Dynamic value) throws IOException {
+
+          var dynamic = new JsonObject();
+
+          dynamic.addProperty("threshold", value.threshold);
+          dynamic.add("hnsw", hnswAdapter.toJsonTree(value.hnsw));
+          dynamic.add("flat", flatAdapter.toJsonTree(value.flat));
+
+          Streams.write(dynamic, out);
+        }
+
+        @Override
+        public Dynamic read(JsonReader in) throws IOException {
+          var jsonObject = JsonParser.parseReader(in).getAsJsonObject();
+
+          var hnsw = hnswAdapter.fromJsonTree(jsonObject.get("hnsw"));
+          var flat = flatAdapter.fromJsonTree(jsonObject.get("flat"));
+          var threshold = jsonObject.get("threshold").getAsLong();
+          return new Dynamic(hnsw, flat, threshold);
+        }
+      }.nullSafe();
+    }
+  }
 }

src/main/java/io/weaviate/client6/v1/internal/json/JSON.java

@@ -28,8 +28,17 @@ public final class JSON {
         io.weaviate.client6.v1.api.collections.Vectors.CustomTypeAdapterFactory.INSTANCE);
     gsonBuilder.registerTypeAdapterFactory(
         io.weaviate.client6.v1.api.collections.VectorConfig.CustomTypeAdapterFactory.INSTANCE);
+
+    // These 2 adapters need to be registered in this exact order: Dynamic
+    // (narrower), VectorIndex (broader).
+    // When searching for an adapter, Gson will pick the first adapter factory that
+    // can process the class, and it's important that Dynamic.class is processed by
+    // this factory.
+    gsonBuilder.registerTypeAdapterFactory(
+        io.weaviate.client6.v1.api.collections.vectorindex.Dynamic.CustomTypeAdapterFactory.INSTANCE);
     gsonBuilder.registerTypeAdapterFactory(
         io.weaviate.client6.v1.api.collections.VectorIndex.CustomTypeAdapterFactory.INSTANCE);
+
     gsonBuilder.registerTypeAdapterFactory(
         io.weaviate.client6.v1.api.collections.Reranker.CustomTypeAdapterFactory.INSTANCE);
     gsonBuilder.registerTypeAdapterFactory(

src/test/java/io/weaviate/client6/v1/internal/json/JSONTest.java

@@ -32,6 +32,7 @@
 import io.weaviate.client6.v1.api.collections.quantizers.PQ;
 import io.weaviate.client6.v1.api.collections.rerankers.CohereReranker;
 import io.weaviate.client6.v1.api.collections.vectorindex.Distance;
+import io.weaviate.client6.v1.api.collections.vectorindex.Dynamic;
 import io.weaviate.client6.v1.api.collections.vectorindex.Flat;
 import io.weaviate.client6.v1.api.collections.vectorindex.Hnsw;
 import io.weaviate.client6.v1.api.collections.vectorindex.MultiVector;
@@ -166,6 +167,28 @@ public static Object[][] testCases() {
                 }
                 """,
         },
+        {
+            VectorConfig.class,
+            SelfProvidedVectorizer.of(none -> none
+                .vectorIndex(Dynamic.of(idx -> idx
+                    .hnsw(Hnsw.of(hnsw -> hnsw
+                        .ef(1)
+                        .efConstruction(2)))
+                    .flat(Flat.of(flat -> flat
+                        .vectorCacheMaxObjects(100)))
+                    .threshold(5)))),
+            """
+                {
+                  "vectorIndexType": "dynamic",
+                  "vectorizer": {"none": {}},
+                  "vectorIndexConfig": {
+                    "flat": {"vectorCacheMaxObjects": 100},
+                    "hnsw": {"ef": 1, "efConstruction": 2},
+                    "threshold": 5
+                  }
+                }
+                """,
+        },
         {
             VectorConfig.class,
             SelfProvidedVectorizer.of(none -> none