From 65b589f5891776aa8116aa10910b67dd6bf72f5b Mon Sep 17 00:00:00 2001
From: dyma solovei <dyma@weaviate.io>
Date: Tue, 7 Oct 2025 12:42:59 +0200
Subject: [PATCH 1/9] feat: support creating, inserting, and reading 'object'
 properties

---
 .../java/io/weaviate/containers/Weaviate.java |  2 +-
 .../integration/CollectionsITest.java         | 23 ++++++
 .../io/weaviate/integration/DataITest.java    | 16 ++--
 .../client6/v1/api/collections/DataType.java  |  4 +-
 .../client6/v1/api/collections/Property.java  | 81 +++++++++++++++++--
 .../api/collections/query/QueryRequest.java   | 12 ++-
 .../client6/v1/internal/orm/MapBuilder.java   |  5 ++
 .../client6/v1/internal/orm/PojoBuilder.java  |  5 ++
 .../v1/internal/orm/PojoDescriptor.java       |  2 +
 .../v1/internal/orm/PropertiesBuilder.java    |  2 +
 10 files changed, 136 insertions(+), 16 deletions(-)

diff --git a/src/it/java/io/weaviate/containers/Weaviate.java b/src/it/java/io/weaviate/containers/Weaviate.java
index 88cd23ee0..661273d74 100644
--- a/src/it/java/io/weaviate/containers/Weaviate.java
+++ b/src/it/java/io/weaviate/containers/Weaviate.java
@@ -15,7 +15,7 @@
 import io.weaviate.client6.v1.internal.ObjectBuilder;
 
 public class Weaviate extends WeaviateContainer {
-  public static final String VERSION = "1.32.3";
+  public static final String VERSION = "1.33.0";
   public static final String DOCKER_IMAGE = "semitechnologies/weaviate";
 
   private volatile SharedClient clientInstance;
diff --git a/src/it/java/io/weaviate/integration/CollectionsITest.java b/src/it/java/io/weaviate/integration/CollectionsITest.java
index 7e21784e6..f37c1eb72 100644
--- a/src/it/java/io/weaviate/integration/CollectionsITest.java
+++ b/src/it/java/io/weaviate/integration/CollectionsITest.java
@@ -10,6 +10,7 @@
 import io.weaviate.client6.v1.api.WeaviateApiException;
 import io.weaviate.client6.v1.api.WeaviateClient;
 import io.weaviate.client6.v1.api.collections.CollectionConfig;
+import io.weaviate.client6.v1.api.collections.DataType;
 import io.weaviate.client6.v1.api.collections.InvertedIndex;
 import io.weaviate.client6.v1.api.collections.Property;
 import io.weaviate.client6.v1.api.collections.ReferenceProperty;
@@ -191,4 +192,26 @@ public void testShards() throws IOException {
   public void testInvalidCollectionName() throws IOException {
     client.collections.create("^collection@weaviate.io$");
   }
+
+  @Test
+  public void testNestedProperties() throws IOException, Exception {
+    var nsBuildings = "Buildings";
+
+    client.collections.create(
+        nsBuildings, c -> c.properties(
+            Property.object("address", p -> p.nestedProperties(
+                Property.text("street"),
+                Property.integer("buildingNr"),
+                Property.bool("isOneWay")))));
+
+    var config = client.collections.getConfig(nsBuildings);
+
+    Assertions.assertThat(config).get()
+        .extracting(CollectionConfig::properties, InstanceOfAssertFactories.list(Property.class))
+        .hasSize(1).first()
+        .returns("address", Property::propertyName)
+        .extracting(Property::nestedProperties, InstanceOfAssertFactories.list(Property.class))
+        .extracting(Property::dataTypes).extracting(types -> types.get(0))
+        .containsExactly(DataType.TEXT, DataType.INT, DataType.BOOL);
+  }
 }
diff --git a/src/it/java/io/weaviate/integration/DataITest.java b/src/it/java/io/weaviate/integration/DataITest.java
index c679f7a7a..7122c63cf 100644
--- a/src/it/java/io/weaviate/integration/DataITest.java
+++ b/src/it/java/io/weaviate/integration/DataITest.java
@@ -431,7 +431,10 @@ public void testDataTypes() throws IOException {
                 Property.boolArray("prop_bool_array"),
                 Property.dateArray("prop_date_array"),
                 Property.uuidArray("prop_uuid_array"),
-                Property.textArray("prop_text_array")));
+                Property.textArray("prop_text_array"),
+                Property.object("prop_object",
+                    p -> p.nestedProperties(
+                        Property.text("marco")))));
 
     var types = client.collections.use(nsDataTypes);
 
@@ -450,13 +453,12 @@ public void testDataTypes() throws IOException {
         Map.entry("prop_bool_array", List.of(true, false)),
         Map.entry("prop_date_array", List.of(now, now)),
         Map.entry("prop_uuid_array", List.of(uuid, uuid)),
-        Map.entry("prop_text_array", List.of("a", "b", "c")));
-    var returnProperties = want.keySet().toArray(String[]::new);
+        Map.entry("prop_text_array", List.of("a", "b", "c")),
+        Map.entry("prop_object", Map.of("marco", "polo")));
 
     // Act
     var object = types.data.insert(want);
-    var got = types.query.byId(object.uuid(),
-        q -> q.returnProperties(returnProperties));
+    var got = types.query.byId(object.uuid()); // return all properties
 
     // Assert
     Assertions.assertThat(got).get()
@@ -465,4 +467,8 @@ public void testDataTypes() throws IOException {
         .containsAllEntriesOf(want);
 
   }
+
+  @Test
+  public void testNestedProperties() throws IOException {
+  }
 }
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/DataType.java b/src/main/java/io/weaviate/client6/v1/api/collections/DataType.java
index 91584a797..7b99e8470 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/DataType.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/DataType.java
@@ -18,6 +18,8 @@ public interface DataType {
   public static final String DATE_ARRAY = "date[]";
   public static final String UUID = "uuid";
   public static final String UUID_ARRAY = "uuid[]";
+  public static final String OBJECT = "object";
+  public static final String OBJECT_ARRAY = "object[]";
 
   /**
    * Scalar/array types which Weaviate and WeaviateClient recognize.
@@ -31,6 +33,6 @@ public interface DataType {
    * using {@link Property}'s factory classes.
    */
   public static final Set<String> KNOWN_TYPES = ImmutableSet.of(
-      TEXT, INT, BLOB, BOOL, DATE, UUID, NUMBER,
+      TEXT, INT, BLOB, BOOL, DATE, UUID, NUMBER, OBJECT,
       TEXT_ARRAY, INT_ARRAY, NUMBER_ARRAY, BOOL_ARRAY, DATE_ARRAY, UUID_ARRAY);
 }
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/Property.java b/src/main/java/io/weaviate/client6/v1/api/collections/Property.java
index 66121675c..f3e69cf3a 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/Property.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/Property.java
@@ -1,5 +1,7 @@
 package io.weaviate.client6.v1.api.collections;
 
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.function.Function;
 
@@ -17,7 +19,8 @@ public record Property(
     @SerializedName("indexSearchable") Boolean indexSearchable,
     @SerializedName("tokenization") Tokenization tokenization,
     @SerializedName("skipVectorization") Boolean skipVectorization,
-    @SerializedName("vectorizePropertyName") Boolean vectorizePropertyName) {
+    @SerializedName("vectorizePropertyName") Boolean vectorizePropertyName,
+    @SerializedName("nestedProperties") List<Property> nestedProperties) {
 
   /**
    * Create a {@code text} property.
@@ -96,7 +99,7 @@ public static Property integerArray(String name, Function<Builder, ObjectBuilder
   }
 
   /**
-   * Create a {@code bool} property.
+   * Create a {@code blob} property.
    *
    * @param name Property name.
    */
@@ -267,6 +270,44 @@ public static Property numberArray(String name, Function<Builder, ObjectBuilder<
     return newProperty(name, DataType.NUMBER_ARRAY, fn);
   }
 
+  /**
+   * Create a {@code object} property.
+   *
+   * @param name Property name.
+   */
+  public static Property object(String name) {
+    return object(name, ObjectBuilder.identity());
+  }
+
+  /**
+   * Create a {@code object} property with additional configuration.
+   *
+   * @param name Property name.
+   * @param fn   Lambda expression for optional parameters.
+   */
+  public static Property object(String name, Function<Builder, ObjectBuilder<Property>> fn) {
+    return newProperty(name, DataType.OBJECT, fn);
+  }
+
+  /**
+   * Create a {@code object[]} property.
+   *
+   * @param name Property name.
+   */
+  public static Property objectArray(String name) {
+    return objectArray(name, ObjectBuilder.identity());
+  }
+
+  /**
+   * Create a {@code objectArray[]} property with additional configuration.
+   *
+   * @param name Property name.
+   * @param fn   Lambda expression for optional parameters.
+   */
+  public static Property objectArray(String name, Function<Builder, ObjectBuilder<Property>> fn) {
+    return newProperty(name, DataType.OBJECT_ARRAY, fn);
+  }
+
   private static Property newProperty(String name, String dataType, Function<Builder, ObjectBuilder<Property>> fn) {
     return fn.apply(new Builder(name, dataType)).build();
   }
@@ -329,7 +370,8 @@ public Property(Builder builder) {
         builder.indexSearchable,
         builder.tokenization,
         builder.skipVectorization,
-        builder.vectorizePropertyName);
+        builder.vectorizePropertyName,
+        builder.nestedProperties.isEmpty() ? null : builder.nestedProperties);
   }
 
   // All methods accepting a `boolean` should have a boxed overload
@@ -346,9 +388,9 @@ public Property(Builder builder) {
   public static class Builder implements ObjectBuilder<Property> {
     // Required parameters.
     private final String propertyName;
+    private final List<String> dataTypes = new ArrayList<>();
 
     // Optional parameters.
-    private List<String> dataTypes;
     private String description;
     private Boolean indexInverted;
     private Boolean indexFilterable;
@@ -357,6 +399,7 @@ public static class Builder implements ObjectBuilder<Property> {
     private Tokenization tokenization;
     private Boolean skipVectorization;
     private Boolean vectorizePropertyName;
+    private List<Property> nestedProperties = new ArrayList<>();
 
     /**
      * Create a scalar / array type property.
@@ -365,7 +408,7 @@ public static class Builder implements ObjectBuilder<Property> {
      */
     public Builder(String propertyName, String dataType) {
       this.propertyName = propertyName;
-      this.dataTypes = List.of(dataType);
+      this.dataTypes.add(dataType);
     }
 
     /**
@@ -375,7 +418,7 @@ public Builder(String propertyName, String dataType) {
      */
     public Builder(String propertyName, List<String> dataTypes) {
       this.propertyName = propertyName;
-      this.dataTypes = List.copyOf(dataTypes);
+      this.dataTypes.addAll(dataTypes);
     }
 
     /** Add property description. */
@@ -491,6 +534,32 @@ public Builder vectorizePropertyName(boolean vectorizePropertyName) {
       return this;
     }
 
+    /**
+     * Defined nested properties. This configuration is only applicable to a
+     * property of type {@code object} and {@code object[]}.
+     *
+     * <pre>{@code
+     * Property.object("address",
+     *     p -> p.nestedProperties(
+     *         Property.text("street"),
+     *         Property.integer("building_nr")))
+     * }</pre>
+     */
+    public Builder nestedProperties(Property... properties) {
+      return nestedProperties(Arrays.asList(properties));
+    }
+
+    /**
+     * Defined nested properties. This configuration is only applicable to a
+     * property of type {@code object} and {@code object[]}.
+     *
+     * @see Builder#nestedProperties(Property...)
+     */
+    public Builder nestedProperties(List<Property> properties) {
+      this.nestedProperties.addAll(properties);
+      return this;
+    }
+
     /** Convenience method to be used by {@link Property#edit}. */
     Builder vectorizePropertyName(Boolean vectorizePropertyName) {
       this.vectorizePropertyName = vectorizePropertyName;
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/query/QueryRequest.java b/src/main/java/io/weaviate/client6/v1/api/collections/query/QueryRequest.java
index fa07d67d5..fd5908b76 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/query/QueryRequest.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/query/QueryRequest.java
@@ -136,8 +136,8 @@ private static <T> WeaviateObject<T, Object, ObjectMetadata> unmarshalWithRefere
       WeaviateProtoSearchGet.MetadataResult metadataResult,
       CollectionDescriptor<T> descriptor) {
     var properties = descriptor.propertiesBuilder();
-    propertiesResult.getNonRefProps().getFieldsMap()
-        .entrySet().stream().forEach(entry -> setProperty(entry.getKey(), entry.getValue(), properties));
+    propertiesResult.getNonRefProps().getFieldsMap().entrySet().stream()
+        .forEach(entry -> setProperty(entry.getKey(), entry.getValue(), properties, descriptor));
 
     // In case a reference is multi-target, there will be a separate
     // "reference property" for each of the targets, so instead of
@@ -213,7 +213,7 @@ private static <T> WeaviateObject<T, Object, ObjectMetadata> unmarshalWithRefere
   }
 
   private static <T> void setProperty(String property, WeaviateProtoProperties.Value value,
-      PropertiesBuilder<T> builder) {
+      PropertiesBuilder<T> builder, CollectionDescriptor<T> descriptor) {
     if (value.hasNullValue()) {
       builder.setNull(property);
     } else if (value.hasTextValue()) {
@@ -255,6 +255,12 @@ private static <T> void setProperty(String property, WeaviateProtoProperties.Val
             .map(DateUtil::fromISO8601).toList();
         builder.setOffsetDateTimeArray(property, dates);
       }
+    } else if (value.hasObjectValue()) {
+      var object = value.getObjectValue();
+      var properties = descriptor.propertiesBuilder();
+      object.getFieldsMap().entrySet().stream()
+          .forEach(entry -> setProperty(entry.getKey(), entry.getValue(), properties, descriptor));
+      builder.setNestedObject(property, properties.build());
     } else {
       throw new IllegalArgumentException(property + " data type is not supported");
     }
diff --git a/src/main/java/io/weaviate/client6/v1/internal/orm/MapBuilder.java b/src/main/java/io/weaviate/client6/v1/internal/orm/MapBuilder.java
index 6d1383160..16d8219bd 100644
--- a/src/main/java/io/weaviate/client6/v1/internal/orm/MapBuilder.java
+++ b/src/main/java/io/weaviate/client6/v1/internal/orm/MapBuilder.java
@@ -79,6 +79,11 @@ public void setOffsetDateTimeArray(String property, List<OffsetDateTime> value)
     properties.put(property, value);
   }
 
+  @Override
+  public void setNestedObject(String property, Object value) {
+    properties.put(property, value);
+  }
+
   @Override
   public Map<String, Object> build() {
     return properties;
diff --git a/src/main/java/io/weaviate/client6/v1/internal/orm/PojoBuilder.java b/src/main/java/io/weaviate/client6/v1/internal/orm/PojoBuilder.java
index 223fd0f53..da9a56309 100644
--- a/src/main/java/io/weaviate/client6/v1/internal/orm/PojoBuilder.java
+++ b/src/main/java/io/weaviate/client6/v1/internal/orm/PojoBuilder.java
@@ -227,6 +227,11 @@ public void setOffsetDateTimeArray(String propertyName, List<OffsetDateTime> val
         : value);
   }
 
+  @Override
+  public void setNestedObject(String propertyName, Object value) {
+    setValue(propertyName, value);
+  }
+
   @Override
   public PropertiesT build() {
     Object[] args = ctorArgs.values().stream().map(Arg::value).toArray();
diff --git a/src/main/java/io/weaviate/client6/v1/internal/orm/PojoDescriptor.java b/src/main/java/io/weaviate/client6/v1/internal/orm/PojoDescriptor.java
index d0a1f218b..0b5724153 100644
--- a/src/main/java/io/weaviate/client6/v1/internal/orm/PojoDescriptor.java
+++ b/src/main/java/io/weaviate/client6/v1/internal/orm/PojoDescriptor.java
@@ -63,6 +63,8 @@ final class PojoDescriptor<T extends Record> implements CollectionDescriptor<T>
         put(Float[].class, Property::numberArray);
         put(double[].class, Property::numberArray);
         put(Double[].class, Property::numberArray);
+
+        put(Map.class, Property::object);
       }
     };
     CTORS = Collections.unmodifiableMap(ctors);
diff --git a/src/main/java/io/weaviate/client6/v1/internal/orm/PropertiesBuilder.java b/src/main/java/io/weaviate/client6/v1/internal/orm/PropertiesBuilder.java
index 797831640..97445d431 100644
--- a/src/main/java/io/weaviate/client6/v1/internal/orm/PropertiesBuilder.java
+++ b/src/main/java/io/weaviate/client6/v1/internal/orm/PropertiesBuilder.java
@@ -33,5 +33,7 @@ public interface PropertiesBuilder<T> {
 
   void setOffsetDateTimeArray(String property, List<OffsetDateTime> value);
 
+  void setNestedObject(String property, Object value);
+
   T build();
 }

From df8b0c7724b7bed0e2aea1fd0e6a069216fb26b6 Mon Sep 17 00:00:00 2001
From: dyma solovei <dyma@weaviate.io>
Date: Tue, 7 Oct 2025 13:22:25 +0200
Subject: [PATCH 2/9] feat: support batch inserting nested objects

---
 .../io/weaviate/integration/DataITest.java    |  28 ++-
 .../collections/data/InsertManyRequest.java   | 230 ++++++++++--------
 2 files changed, 155 insertions(+), 103 deletions(-)

diff --git a/src/it/java/io/weaviate/integration/DataITest.java b/src/it/java/io/weaviate/integration/DataITest.java
index 7122c63cf..7762d8a00 100644
--- a/src/it/java/io/weaviate/integration/DataITest.java
+++ b/src/it/java/io/weaviate/integration/DataITest.java
@@ -469,6 +469,32 @@ public void testDataTypes() throws IOException {
   }
 
   @Test
-  public void testNestedProperties() throws IOException {
+  public void testNestedProperties_insertMany() throws IOException {
+    // Arrange
+    var nsBuildings = "Buildings";
+
+    client.collections.create(
+        nsBuildings, c -> c.properties(
+            Property.object("address", p -> p.nestedProperties(
+                Property.text("street"),
+                Property.integer("buildingNr"),
+                Property.bool("isOneWay")))));
+
+    var buildings = client.collections.use("nsBuildings");
+
+    Map<String, Object> house_1 = Map.of("address", Map.of(
+        "street", "Burggasse",
+        "building_nr", 51,
+        "isOneWay", true));
+    Map<String, Object> house_2 = Map.of("address", Map.of(
+        "street", "Port Mariland St.",
+        "building_nr", 111,
+        "isOneWay", false));
+
+    // Act
+    var result = buildings.data.insertMany(house_1, house_2);
+
+    // Assert
+    Assertions.assertThat(result.errors()).isEmpty();
   }
 }
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java b/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
index b4d86cfbc..3ff4399a2 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
@@ -4,11 +4,13 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 import java.util.UUID;
 
 import io.weaviate.client6.v1.api.collections.CollectionHandleDefaults;
 import io.weaviate.client6.v1.api.collections.ObjectMetadata;
 import io.weaviate.client6.v1.api.collections.WeaviateObject;
+import io.weaviate.client6.v1.internal.Debug;
 import io.weaviate.client6.v1.internal.MapUtil;
 import io.weaviate.client6.v1.internal.grpc.ByteStringUtil;
 import io.weaviate.client6.v1.internal.grpc.Rpc;
@@ -136,110 +138,15 @@ public static <T> void buildObject(WeaviateProtoBatch.BatchObject.Builder object
     collection
         .propertiesReader(insert.properties()).readProperties()
         .entrySet().stream().forEach(entry -> {
-          var value = entry.getValue();
-          var protoValue = com.google.protobuf.Value.newBuilder();
-
-          if (value == null) {
-            return;
-          }
-
-          if (value instanceof String v) {
-            protoValue.setStringValue(v);
-          } else if (value instanceof UUID v) {
-            protoValue.setStringValue(v.toString());
-          } else if (value instanceof OffsetDateTime v) {
-            protoValue.setStringValue(v.toString());
-          } else if (value instanceof Boolean v) {
-            protoValue.setBoolValue(v.booleanValue());
-          } else if (value instanceof Number v) {
-            protoValue.setNumberValue(v.doubleValue());
-          } else if (value instanceof List<?> v) {
-            protoValue.setListValue(
-                com.google.protobuf.ListValue.newBuilder()
-                    .addAllValues(v.stream()
-                        .map(listValue -> {
-                          var protoListValue = com.google.protobuf.Value.newBuilder();
-                          if (listValue instanceof String lv) {
-                            protoListValue.setStringValue(lv);
-                          } else if (listValue instanceof UUID lv) {
-                            protoListValue.setStringValue(lv.toString());
-                          } else if (listValue instanceof OffsetDateTime lv) {
-                            protoListValue.setStringValue(lv.toString());
-                          } else if (listValue instanceof Boolean lv) {
-                            protoListValue.setBoolValue(lv);
-                          } else if (listValue instanceof Number lv) {
-                            protoListValue.setNumberValue(lv.doubleValue());
-                          }
-                          return protoListValue.build();
-                        })
-                        .toList()));
-
-          } else if (value.getClass().isArray()) {
-            List<com.google.protobuf.Value> values;
-
-            if (value instanceof String[] v) {
-              values = Arrays.stream(v)
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setStringValue(lv).build()).toList();
-            } else if (value instanceof UUID[] v) {
-              values = Arrays.stream(v)
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setStringValue(lv.toString()).build()).toList();
-            } else if (value instanceof OffsetDateTime[] v) {
-              values = Arrays.stream(v)
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setStringValue(lv.toString()).build()).toList();
-            } else if (value instanceof Boolean[] v) {
-              values = Arrays.stream(v)
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setBoolValue(lv).build()).toList();
-            } else if (value instanceof boolean[] v) {
-              values = new ArrayList<>();
-              for (boolean b : v) {
-                values.add(com.google.protobuf.Value.newBuilder().setBoolValue(b).build());
-              }
-            } else if (value instanceof short[] v) {
-              values = new ArrayList<>();
-              for (short s : v) {
-                values.add(com.google.protobuf.Value.newBuilder().setNumberValue(s).build());
-              }
-            } else if (value instanceof int[] v) {
-              values = Arrays.stream(v).boxed()
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
-            } else if (value instanceof long[] v) {
-              values = Arrays.stream(v).boxed()
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
-            } else if (value instanceof float[] v) {
-              values = new ArrayList<>();
-              for (float s : v) {
-                values.add(com.google.protobuf.Value.newBuilder().setNumberValue(s).build());
-              }
-            } else if (value instanceof double[] v) {
-              values = Arrays.stream(v).boxed()
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
-            } else if (value instanceof Short[] v) {
-              values = Arrays.stream(v)
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
-            } else if (value instanceof Integer[] v) {
-              values = Arrays.stream(v)
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
-            } else if (value instanceof Long[] v) {
-              values = Arrays.stream(v)
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
-            } else if (value instanceof Float[] v) {
-              values = Arrays.stream(v)
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
-            } else if (value instanceof Double[] v) {
-              values = Arrays.stream(v)
-                  .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
-            } else {
-              throw new AssertionError("(insertMany) branch not covered " + value.getClass());
+          try {
+            var protoValue = marshalValue(entry.getValue());
+            if (protoValue == null) {
+              return;
             }
-
-            protoValue.setListValue(com.google.protobuf.ListValue.newBuilder()
-                .addAllValues(values)
-                .build());
-          } else {
-            throw new AssertionError("(insertMany) branch not covered " + value.getClass());
+            nonRef.putFields(entry.getKey(), protoValue);
+          } catch (IllegalArgumentException e) {
+            throw new IllegalArgumentException("marshal property " + entry.getKey(), e);
           }
-
-          nonRef.putFields(entry.getKey(), protoValue.build());
         });
 
     insert.references()
@@ -272,5 +179,124 @@ public static <T> void buildObject(WeaviateProtoBatch.BatchObject.Builder object
         .addAllMultiTargetRefProps(multiRef);
 
     object.setProperties(properties);
+
+    Debug.printProto(object);
+  }
+
+  private static com.google.protobuf.Value marshalValue(Object value) {
+    var protoValue = com.google.protobuf.Value.newBuilder();
+
+    if (value == null) {
+      return null;
+    }
+
+    if (value instanceof String v) {
+      protoValue.setStringValue(v);
+    } else if (value instanceof UUID v) {
+      protoValue.setStringValue(v.toString());
+    } else if (value instanceof OffsetDateTime v) {
+      protoValue.setStringValue(v.toString());
+    } else if (value instanceof Boolean v) {
+      protoValue.setBoolValue(v.booleanValue());
+    } else if (value instanceof Number v) {
+      protoValue.setNumberValue(v.doubleValue());
+    } else if (value instanceof List<?> v) {
+      protoValue.setListValue(
+          com.google.protobuf.ListValue.newBuilder()
+              .addAllValues(v.stream()
+                  .map(listValue -> {
+                    var protoListValue = com.google.protobuf.Value.newBuilder();
+                    if (listValue instanceof String lv) {
+                      protoListValue.setStringValue(lv);
+                    } else if (listValue instanceof UUID lv) {
+                      protoListValue.setStringValue(lv.toString());
+                    } else if (listValue instanceof OffsetDateTime lv) {
+                      protoListValue.setStringValue(lv.toString());
+                    } else if (listValue instanceof Boolean lv) {
+                      protoListValue.setBoolValue(lv);
+                    } else if (listValue instanceof Number lv) {
+                      protoListValue.setNumberValue(lv.doubleValue());
+                    }
+                    return protoListValue.build();
+                  })
+                  .toList()));
+
+    } else if (value.getClass().isArray()) {
+      List<com.google.protobuf.Value> values;
+
+      if (value instanceof String[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder().setStringValue(lv).build()).toList();
+      } else if (value instanceof UUID[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder().setStringValue(lv.toString()).build()).toList();
+      } else if (value instanceof OffsetDateTime[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder().setStringValue(lv.toString()).build()).toList();
+      } else if (value instanceof Boolean[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder().setBoolValue(lv).build()).toList();
+      } else if (value instanceof boolean[] v) {
+        values = new ArrayList<>();
+        for (boolean b : v) {
+          values.add(com.google.protobuf.Value.newBuilder().setBoolValue(b).build());
+        }
+      } else if (value instanceof short[] v) {
+        values = new ArrayList<>();
+        for (short s : v) {
+          values.add(com.google.protobuf.Value.newBuilder().setNumberValue(s).build());
+        }
+      } else if (value instanceof int[] v) {
+        values = Arrays.stream(v).boxed()
+            .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
+      } else if (value instanceof long[] v) {
+        values = Arrays.stream(v).boxed()
+            .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
+      } else if (value instanceof float[] v) {
+        values = new ArrayList<>();
+        for (float s : v) {
+          values.add(com.google.protobuf.Value.newBuilder().setNumberValue(s).build());
+        }
+      } else if (value instanceof double[] v) {
+        values = Arrays.stream(v).boxed()
+            .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
+      } else if (value instanceof Short[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
+      } else if (value instanceof Integer[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
+      } else if (value instanceof Long[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
+      } else if (value instanceof Float[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
+      } else if (value instanceof Double[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
+      } else {
+        throw new IllegalArgumentException("array type " + value.getClass() + " is not supported");
+      }
+
+      protoValue.setListValue(com.google.protobuf.ListValue.newBuilder()
+          .addAllValues(values)
+          .build());
+    } else if (value instanceof Map<?, ?> v) {
+      var protoNested = com.google.protobuf.Struct.newBuilder();
+      v.entrySet().stream()
+          .forEach(nested -> {
+            var nestedValue = marshalValue(nested.getValue());
+            if (nestedValue == null) {
+              return;
+            }
+            protoNested.putFields((String) nested.getKey(), nestedValue);
+          });
+      protoValue.setStructValue(protoNested);
+    } else {
+      throw new IllegalArgumentException("data type " + value.getClass() + " is not supported");
+    }
+
+    return protoValue.build();
   }
 }

From aba509414aad06b276e811ff2b5f778db14d5314 Mon Sep 17 00:00:00 2001
From: dyma solovei <dyma@weaviate.io>
Date: Tue, 7 Oct 2025 15:56:10 +0200
Subject: [PATCH 3/9] feat: support writing records as nested properties

---
 src/it/java/io/weaviate/integration/DataITest.java | 14 ++++++++++----
 .../v1/api/collections/data/InsertManyRequest.java | 14 ++++++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/it/java/io/weaviate/integration/DataITest.java b/src/it/java/io/weaviate/integration/DataITest.java
index 7762d8a00..fee4f07ef 100644
--- a/src/it/java/io/weaviate/integration/DataITest.java
+++ b/src/it/java/io/weaviate/integration/DataITest.java
@@ -468,6 +468,12 @@ public void testDataTypes() throws IOException {
 
   }
 
+  record Address(
+      String street,
+      @io.weaviate.client6.v1.api.collections.annotations.Property("building_nr") int buildingNr,
+      @io.weaviate.client6.v1.api.collections.annotations.Property("isOneWay") boolean oneWay) {
+  }
+
   @Test
   public void testNestedProperties_insertMany() throws IOException {
     // Arrange
@@ -486,10 +492,10 @@ public void testNestedProperties_insertMany() throws IOException {
         "street", "Burggasse",
         "building_nr", 51,
         "isOneWay", true));
-    Map<String, Object> house_2 = Map.of("address", Map.of(
-        "street", "Port Mariland St.",
-        "building_nr", 111,
-        "isOneWay", false));
+    Map<String, Object> house_2 = Map.of("address", new Address(
+        "Port Mariland St.",
+        111,
+        false));
 
     // Act
     var result = buildings.data.insertMany(house_1, house_2);
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java b/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
index 3ff4399a2..0f24cff35 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
@@ -293,6 +293,20 @@ private static com.google.protobuf.Value marshalValue(Object value) {
             protoNested.putFields((String) nested.getKey(), nestedValue);
           });
       protoValue.setStructValue(protoNested);
+    } else if (value instanceof Record r) {
+      @SuppressWarnings("unchecked")
+      CollectionDescriptor<? super Record> recordDescriptor = (CollectionDescriptor<? super Record>) CollectionDescriptor
+          .ofClass(r.getClass());
+      var protoRecord = com.google.protobuf.Struct.newBuilder();
+      recordDescriptor.propertiesReader(r).readProperties().entrySet().stream()
+          .forEach(recordField -> {
+            var nestedValue = marshalValue(recordField.getValue());
+            if (nestedValue == null) {
+              return;
+            }
+            protoRecord.putFields((String) recordField.getKey(), nestedValue);
+          });
+      protoValue.setStructValue(protoRecord);
     } else {
       throw new IllegalArgumentException("data type " + value.getClass() + " is not supported");
     }

From b61086f73b719762d30483b80bf36c341fcc8a0d Mon Sep 17 00:00:00 2001
From: dyma solovei <dyma@weaviate.io>
Date: Tue, 7 Oct 2025 16:36:40 +0200
Subject: [PATCH 4/9] refactor: factor out marshaling a Struct

This is done 3 times:
1. High-level properties
2. Map<String, Object>
3. Custom records
---
 .../io/weaviate/integration/DataITest.java    |  2 +-
 .../collections/data/InsertManyRequest.java   | 63 +++++++------------
 2 files changed, 22 insertions(+), 43 deletions(-)

diff --git a/src/it/java/io/weaviate/integration/DataITest.java b/src/it/java/io/weaviate/integration/DataITest.java
index fee4f07ef..abb627c47 100644
--- a/src/it/java/io/weaviate/integration/DataITest.java
+++ b/src/it/java/io/weaviate/integration/DataITest.java
@@ -486,7 +486,7 @@ public void testNestedProperties_insertMany() throws IOException {
                 Property.integer("buildingNr"),
                 Property.bool("isOneWay")))));
 
-    var buildings = client.collections.use("nsBuildings");
+    var buildings = client.collections.use(nsBuildings);
 
     Map<String, Object> house_1 = Map.of("address", Map.of(
         "street", "Burggasse",
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java b/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
index 0f24cff35..fff3ba479 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
@@ -130,25 +130,9 @@ public static <T> void buildObject(WeaviateProtoBatch.BatchObject.Builder object
       }
     }
 
-    var properties = WeaviateProtoBatch.BatchObject.Properties.newBuilder();
-    var nonRef = com.google.protobuf.Struct.newBuilder();
     var singleRef = new ArrayList<WeaviateProtoBatch.BatchObject.SingleTargetRefProps>();
     var multiRef = new ArrayList<WeaviateProtoBatch.BatchObject.MultiTargetRefProps>();
 
-    collection
-        .propertiesReader(insert.properties()).readProperties()
-        .entrySet().stream().forEach(entry -> {
-          try {
-            var protoValue = marshalValue(entry.getValue());
-            if (protoValue == null) {
-              return;
-            }
-            nonRef.putFields(entry.getKey(), protoValue);
-          } catch (IllegalArgumentException e) {
-            throw new IllegalArgumentException("marshal property " + entry.getKey(), e);
-          }
-        });
-
     insert.references()
         .entrySet().stream().forEach(entry -> {
           var references = entry.getValue();
@@ -173,16 +157,16 @@ public static <T> void buildObject(WeaviateProtoBatch.BatchObject.Builder object
           }
         });
 
-    properties
+    var nonRef = marshalStruct(collection.propertiesReader(insert.properties()).readProperties());
+    object.setProperties(WeaviateProtoBatch.BatchObject.Properties.newBuilder()
         .setNonRefProperties(nonRef)
         .addAllSingleTargetRefProps(singleRef)
-        .addAllMultiTargetRefProps(multiRef);
-
-    object.setProperties(properties);
+        .addAllMultiTargetRefProps(multiRef));
 
     Debug.printProto(object);
   }
 
+  @SuppressWarnings("unchecked")
   private static com.google.protobuf.Value marshalValue(Object value) {
     var protoValue = com.google.protobuf.Value.newBuilder();
 
@@ -282,35 +266,30 @@ private static com.google.protobuf.Value marshalValue(Object value) {
       protoValue.setListValue(com.google.protobuf.ListValue.newBuilder()
           .addAllValues(values)
           .build());
-    } else if (value instanceof Map<?, ?> v) {
-      var protoNested = com.google.protobuf.Struct.newBuilder();
-      v.entrySet().stream()
-          .forEach(nested -> {
-            var nestedValue = marshalValue(nested.getValue());
-            if (nestedValue == null) {
-              return;
-            }
-            protoNested.putFields((String) nested.getKey(), nestedValue);
-          });
-      protoValue.setStructValue(protoNested);
+    } else if (value instanceof Map<?, ?> properties) {
+      protoValue.setStructValue(marshalStruct((Map<String, Object>) properties));
     } else if (value instanceof Record r) {
-      @SuppressWarnings("unchecked")
       CollectionDescriptor<? super Record> recordDescriptor = (CollectionDescriptor<? super Record>) CollectionDescriptor
           .ofClass(r.getClass());
-      var protoRecord = com.google.protobuf.Struct.newBuilder();
-      recordDescriptor.propertiesReader(r).readProperties().entrySet().stream()
-          .forEach(recordField -> {
-            var nestedValue = marshalValue(recordField.getValue());
-            if (nestedValue == null) {
-              return;
-            }
-            protoRecord.putFields((String) recordField.getKey(), nestedValue);
-          });
-      protoValue.setStructValue(protoRecord);
+      var properties = recordDescriptor.propertiesReader(r).readProperties();
+      protoValue.setStructValue(marshalStruct(properties));
     } else {
       throw new IllegalArgumentException("data type " + value.getClass() + " is not supported");
     }
 
     return protoValue.build();
   }
+
+  private static com.google.protobuf.Struct marshalStruct(Map<String, Object> properties) {
+    var struct = com.google.protobuf.Struct.newBuilder();
+    properties.entrySet().stream()
+        .forEach(entry -> {
+          var nestedValue = marshalValue(entry.getValue());
+          if (nestedValue == null) {
+            return;
+          }
+          struct.putFields((String) entry.getKey(), nestedValue);
+        });
+    return struct.build();
+  }
 }

From cafb7ae88c87819d1ebd1436c08283473f30e8fc Mon Sep 17 00:00:00 2001
From: dyma solovei <dyma@weaviate.io>
Date: Tue, 7 Oct 2025 17:22:58 +0200
Subject: [PATCH 5/9] feat: support object[] properties

---
 .../integration/CollectionsITest.java         | 21 ++++++++--
 .../io/weaviate/integration/DataITest.java    | 38 +++++++++++++------
 .../io/weaviate/integration/ORMITest.java     |  4 ++
 .../client6/v1/api/collections/DataType.java  |  2 +-
 .../collections/data/InsertManyRequest.java   | 27 +++++++++++++
 .../api/collections/query/QueryRequest.java   |  9 +++++
 .../client6/v1/internal/orm/MapBuilder.java   |  5 +++
 .../client6/v1/internal/orm/PojoBuilder.java  |  7 +++-
 .../v1/internal/orm/PropertiesBuilder.java    |  2 +
 9 files changed, 98 insertions(+), 17 deletions(-)

diff --git a/src/it/java/io/weaviate/integration/CollectionsITest.java b/src/it/java/io/weaviate/integration/CollectionsITest.java
index f37c1eb72..e70503723 100644
--- a/src/it/java/io/weaviate/integration/CollectionsITest.java
+++ b/src/it/java/io/weaviate/integration/CollectionsITest.java
@@ -201,17 +201,30 @@ public void testNestedProperties() throws IOException, Exception {
         nsBuildings, c -> c.properties(
             Property.object("address", p -> p.nestedProperties(
                 Property.text("street"),
-                Property.integer("buildingNr"),
-                Property.bool("isOneWay")))));
+                Property.integer("building_nr"),
+                Property.bool("isOneWay"))),
+            Property.objectArray("apartments", p -> p.nestedProperties(
+                Property.integer("door_nr"),
+                Property.number("area")))));
 
     var config = client.collections.getConfig(nsBuildings);
 
-    Assertions.assertThat(config).get()
+    var properties = Assertions.assertThat(config).get()
         .extracting(CollectionConfig::properties, InstanceOfAssertFactories.list(Property.class))
-        .hasSize(1).first()
+        .hasSize(2).actual();
+
+    Assertions.assertThat(properties.get(0))
         .returns("address", Property::propertyName)
+        .returns(DataType.OBJECT, p -> p.dataTypes().get(0))
         .extracting(Property::nestedProperties, InstanceOfAssertFactories.list(Property.class))
         .extracting(Property::dataTypes).extracting(types -> types.get(0))
         .containsExactly(DataType.TEXT, DataType.INT, DataType.BOOL);
+
+    Assertions.assertThat(properties.get(1))
+        .returns("apartments", Property::propertyName)
+        .returns(DataType.OBJECT_ARRAY, p -> p.dataTypes().get(0))
+        .extracting(Property::nestedProperties, InstanceOfAssertFactories.list(Property.class))
+        .extracting(Property::dataTypes).extracting(types -> types.get(0))
+        .containsExactly(DataType.INT, DataType.NUMBER);
   }
 }
diff --git a/src/it/java/io/weaviate/integration/DataITest.java b/src/it/java/io/weaviate/integration/DataITest.java
index abb627c47..38812b877 100644
--- a/src/it/java/io/weaviate/integration/DataITest.java
+++ b/src/it/java/io/weaviate/integration/DataITest.java
@@ -433,6 +433,9 @@ public void testDataTypes() throws IOException {
                 Property.uuidArray("prop_uuid_array"),
                 Property.textArray("prop_text_array"),
                 Property.object("prop_object",
+                    p -> p.nestedProperties(
+                        Property.text("marco"))),
+                Property.objectArray("prop_object_array",
                     p -> p.nestedProperties(
                         Property.text("marco")))));
 
@@ -454,7 +457,8 @@ public void testDataTypes() throws IOException {
         Map.entry("prop_date_array", List.of(now, now)),
         Map.entry("prop_uuid_array", List.of(uuid, uuid)),
         Map.entry("prop_text_array", List.of("a", "b", "c")),
-        Map.entry("prop_object", Map.of("marco", "polo")));
+        Map.entry("prop_object", Map.of("marco", "polo")),
+        Map.entry("prop_object_array", List.of(Map.of("marco", "polo"))));
 
     // Act
     var object = types.data.insert(want);
@@ -483,19 +487,31 @@ public void testNestedProperties_insertMany() throws IOException {
         nsBuildings, c -> c.properties(
             Property.object("address", p -> p.nestedProperties(
                 Property.text("street"),
-                Property.integer("buildingNr"),
-                Property.bool("isOneWay")))));
+                Property.integer("building_nr"),
+                Property.bool("isOneWay"))),
+            Property.objectArray("apartments", p -> p.nestedProperties(
+                Property.integer("door_nr"),
+                Property.number("area")))));
 
     var buildings = client.collections.use(nsBuildings);
 
-    Map<String, Object> house_1 = Map.of("address", Map.of(
-        "street", "Burggasse",
-        "building_nr", 51,
-        "isOneWay", true));
-    Map<String, Object> house_2 = Map.of("address", new Address(
-        "Port Mariland St.",
-        111,
-        false));
+    Map<String, Object> house_1 = Map.of(
+        "address", Map.of(
+            "street", "Burggasse",
+            "building_nr", 51,
+            "isOneWay", true),
+        "apartments", List.of(
+            Map.of("door_nr", 11, "area", 42.2),
+            Map.of("door_nr", 12, "area", 26.7)));
+    Map<String, Object> house_2 = Map.of(
+        "address", new Address(
+            "Port Mariland St.",
+            111,
+            false),
+        "apartments", new Map[] {
+            Map.of("door_nr", 21, "area", 42.2),
+            Map.of("door_nr", 22, "area", 26.7),
+        });
 
     // Act
     var result = buildings.data.insertMany(house_1, house_2);
diff --git a/src/it/java/io/weaviate/integration/ORMITest.java b/src/it/java/io/weaviate/integration/ORMITest.java
index 16b5b3717..e732738fb 100644
--- a/src/it/java/io/weaviate/integration/ORMITest.java
+++ b/src/it/java/io/weaviate/integration/ORMITest.java
@@ -350,4 +350,8 @@ public void test_partialScan() throws IOException {
         .returns(true, Song::hasAward)
         .returns(null, Song::monthlyListeners);
   }
+
+  @Test
+  public void test_nestedProperties() throws IOException {
+  }
 }
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/DataType.java b/src/main/java/io/weaviate/client6/v1/api/collections/DataType.java
index 7b99e8470..67044e22c 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/DataType.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/DataType.java
@@ -34,5 +34,5 @@ public interface DataType {
    */
   public static final Set<String> KNOWN_TYPES = ImmutableSet.of(
       TEXT, INT, BLOB, BOOL, DATE, UUID, NUMBER, OBJECT,
-      TEXT_ARRAY, INT_ARRAY, NUMBER_ARRAY, BOOL_ARRAY, DATE_ARRAY, UUID_ARRAY);
+      TEXT_ARRAY, INT_ARRAY, NUMBER_ARRAY, BOOL_ARRAY, DATE_ARRAY, UUID_ARRAY, OBJECT_ARRAY);
 }
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java b/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
index fff3ba479..4475f178d 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/data/InsertManyRequest.java
@@ -200,6 +200,15 @@ private static com.google.protobuf.Value marshalValue(Object value) {
                       protoListValue.setBoolValue(lv);
                     } else if (listValue instanceof Number lv) {
                       protoListValue.setNumberValue(lv.doubleValue());
+                    } else if (listValue instanceof Map<?, ?> properties) {
+                      protoListValue.setStructValue(marshalStruct((Map<String, Object>) properties));
+                    } else if (listValue instanceof Record r) {
+                      CollectionDescriptor<? super Record> recordDescriptor = (CollectionDescriptor<? super Record>) CollectionDescriptor
+                          .ofClass(r.getClass());
+                      var properties = recordDescriptor.propertiesReader(r).readProperties();
+                      protoListValue.setStructValue(marshalStruct(properties));
+                    } else {
+                      throw new IllegalArgumentException("data type " + value.getClass() + " is not supported");
                     }
                     return protoListValue.build();
                   })
@@ -259,6 +268,24 @@ private static com.google.protobuf.Value marshalValue(Object value) {
       } else if (value instanceof Double[] v) {
         values = Arrays.stream(v)
             .map(lv -> com.google.protobuf.Value.newBuilder().setNumberValue(lv).build()).toList();
+      } else if (value instanceof Map[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> com.google.protobuf.Value.newBuilder()
+                .setStructValue(marshalStruct((Map<String, Object>) lv))
+                .build())
+            .toList();
+      } else if (value instanceof Record[] v) {
+        values = Arrays.stream(v)
+            .map(lv -> {
+              // Get the descriptor for each iteration in case the array is heterogenous.
+              final CollectionDescriptor<? super Record> recordDescriptor = (CollectionDescriptor<? super Record>) CollectionDescriptor
+                  .ofClass(lv.getClass());
+              var properties = recordDescriptor.propertiesReader(lv).readProperties();
+              return com.google.protobuf.Value.newBuilder()
+                  .setStructValue(marshalStruct(properties))
+                  .build();
+            })
+            .toList();
       } else {
         throw new IllegalArgumentException("array type " + value.getClass() + " is not supported");
       }
diff --git a/src/main/java/io/weaviate/client6/v1/api/collections/query/QueryRequest.java b/src/main/java/io/weaviate/client6/v1/api/collections/query/QueryRequest.java
index fd5908b76..11d31b4e5 100644
--- a/src/main/java/io/weaviate/client6/v1/api/collections/query/QueryRequest.java
+++ b/src/main/java/io/weaviate/client6/v1/api/collections/query/QueryRequest.java
@@ -254,6 +254,15 @@ private static <T> void setProperty(String property, WeaviateProtoProperties.Val
         var dates = list.getDateValues().getValuesList().stream()
             .map(DateUtil::fromISO8601).toList();
         builder.setOffsetDateTimeArray(property, dates);
+      } else if (list.hasObjectValues()) {
+        List<? extends Object> objects = list.getObjectValues().getValuesList().stream()
+            .map(object -> {
+              var properties = descriptor.propertiesBuilder();
+              object.getFieldsMap().entrySet().stream()
+                  .forEach(entry -> setProperty(entry.getKey(), entry.getValue(), properties, descriptor));
+              return properties.build();
+            }).toList();
+        builder.setNestedObjectArray(property, objects);
       }
     } else if (value.hasObjectValue()) {
       var object = value.getObjectValue();
diff --git a/src/main/java/io/weaviate/client6/v1/internal/orm/MapBuilder.java b/src/main/java/io/weaviate/client6/v1/internal/orm/MapBuilder.java
index 16d8219bd..0c044e3c9 100644
--- a/src/main/java/io/weaviate/client6/v1/internal/orm/MapBuilder.java
+++ b/src/main/java/io/weaviate/client6/v1/internal/orm/MapBuilder.java
@@ -84,6 +84,11 @@ public void setNestedObject(String property, Object value) {
     properties.put(property, value);
   }
 
+  @Override
+  public void setNestedObjectArray(String property, List<? extends Object> value) {
+    properties.put(property, value);
+  }
+
   @Override
   public Map<String, Object> build() {
     return properties;
diff --git a/src/main/java/io/weaviate/client6/v1/internal/orm/PojoBuilder.java b/src/main/java/io/weaviate/client6/v1/internal/orm/PojoBuilder.java
index da9a56309..085811565 100644
--- a/src/main/java/io/weaviate/client6/v1/internal/orm/PojoBuilder.java
+++ b/src/main/java/io/weaviate/client6/v1/internal/orm/PojoBuilder.java
@@ -229,7 +229,12 @@ public void setOffsetDateTimeArray(String propertyName, List<OffsetDateTime> val
 
   @Override
   public void setNestedObject(String propertyName, Object value) {
-    setValue(propertyName, value);
+    throw new UnsupportedOperationException("Unimplemented method 'setNestedObjectArray'");
+  }
+
+  @Override
+  public void setNestedObjectArray(String property, List<? extends Object> value) {
+    throw new UnsupportedOperationException("Unimplemented method 'setNestedObjectArray'");
   }
 
   @Override
diff --git a/src/main/java/io/weaviate/client6/v1/internal/orm/PropertiesBuilder.java b/src/main/java/io/weaviate/client6/v1/internal/orm/PropertiesBuilder.java
index 97445d431..81e8ec5e4 100644
--- a/src/main/java/io/weaviate/client6/v1/internal/orm/PropertiesBuilder.java
+++ b/src/main/java/io/weaviate/client6/v1/internal/orm/PropertiesBuilder.java
@@ -35,5 +35,7 @@ public interface PropertiesBuilder<T> {
 
   void setNestedObject(String property, Object value);
 
+  void setNestedObjectArray(String property, List<? extends Object> value);
+
   T build();
 }

From d0a83a5dca2368a1d2dbe32c89125f06495165ea Mon Sep 17 00:00:00 2001
From: dyma solovei <dyma@weaviate.io>
Date: Tue, 7 Oct 2025 17:25:08 +0200
Subject: [PATCH 6/9] test: use unique collection names

---
 src/it/java/io/weaviate/integration/CollectionsITest.java | 2 +-
 src/it/java/io/weaviate/integration/DataITest.java        | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/it/java/io/weaviate/integration/CollectionsITest.java b/src/it/java/io/weaviate/integration/CollectionsITest.java
index e70503723..975ebba76 100644
--- a/src/it/java/io/weaviate/integration/CollectionsITest.java
+++ b/src/it/java/io/weaviate/integration/CollectionsITest.java
@@ -195,7 +195,7 @@ public void testInvalidCollectionName() throws IOException {
 
   @Test
   public void testNestedProperties() throws IOException, Exception {
-    var nsBuildings = "Buildings";
+    var nsBuildings = ns("Buildings");
 
     client.collections.create(
         nsBuildings, c -> c.properties(
diff --git a/src/it/java/io/weaviate/integration/DataITest.java b/src/it/java/io/weaviate/integration/DataITest.java
index 38812b877..693eccea4 100644
--- a/src/it/java/io/weaviate/integration/DataITest.java
+++ b/src/it/java/io/weaviate/integration/DataITest.java
@@ -481,7 +481,7 @@ record Address(
   @Test
   public void testNestedProperties_insertMany() throws IOException {
     // Arrange
-    var nsBuildings = "Buildings";
+    var nsBuildings = ns("Buildings");
 
     client.collections.create(
         nsBuildings, c -> c.properties(

From 618b22d84535882bbd2ba7b1a4e086a41af97641 Mon Sep 17 00:00:00 2001
From: dyma solovei <dyma@weaviate.io>
Date: Tue, 7 Oct 2025 17:29:23 +0200
Subject: [PATCH 7/9] test: bork local connection to prompt exception

---
 .../io/weaviate/client6/v1/api/WeaviateClientAsyncTest.java     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/test/java/io/weaviate/client6/v1/api/WeaviateClientAsyncTest.java b/src/test/java/io/weaviate/client6/v1/api/WeaviateClientAsyncTest.java
index e538de7a0..60e46de46 100644
--- a/src/test/java/io/weaviate/client6/v1/api/WeaviateClientAsyncTest.java
+++ b/src/test/java/io/weaviate/client6/v1/api/WeaviateClientAsyncTest.java
@@ -14,7 +14,7 @@ public void testFailedConnection() {
 
   @Test(expected = WeaviateConnectException.class)
   public void testFailedConnection_Local() {
-    WeaviateClientAsync.connectToLocal();
+    WeaviateClientAsync.connectToLocal(conn -> conn.port(1234));
   }
 
   @Test(expected = WeaviateConnectException.class)

From a0c9ca2cad32d0a7df52a3614e7a51e870eccb14 Mon Sep 17 00:00:00 2001
From: dyma solovei <dyma@weaviate.io>
Date: Tue, 7 Oct 2025 17:30:12 +0200
Subject: [PATCH 8/9] chore: force GSON to respect int/long

Default behaviour is converting everything to floats,
which may be confusing especially when logging request bodies
---
 src/main/java/io/weaviate/client6/v1/internal/json/JSON.java | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/main/java/io/weaviate/client6/v1/internal/json/JSON.java b/src/main/java/io/weaviate/client6/v1/internal/json/JSON.java
index 3d2e00089..e1f0040f2 100644
--- a/src/main/java/io/weaviate/client6/v1/internal/json/JSON.java
+++ b/src/main/java/io/weaviate/client6/v1/internal/json/JSON.java
@@ -2,6 +2,7 @@
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
+import com.google.gson.ToNumberPolicy;
 import com.google.gson.reflect.TypeToken;
 
 import io.weaviate.client6.v1.internal.orm.PropertyFieldNamingStrategy;
@@ -49,6 +50,8 @@ public final class JSON {
 
     // ORM FieldNaminsStrategy ------------------------------------------------
     gsonBuilder.setFieldNamingStrategy(PropertyFieldNamingStrategy.INSTANCE);
+
+    gsonBuilder.setObjectToNumberStrategy(ToNumberPolicy.LONG_OR_DOUBLE);
     gson = gsonBuilder.create();
   }
 

From e4e12f029731bb8187fa56c5036855af682efd97 Mon Sep 17 00:00:00 2001
From: dyma solovei <dyma@weaviate.io>
Date: Thu, 9 Oct 2025 11:10:54 +0200
Subject: [PATCH 9/9] docs: mention nested properties in the README

---
 README.md | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/README.md b/README.md
index 1ba9b291d..5a77b0020 100644
--- a/README.md
+++ b/README.md
@@ -668,10 +668,22 @@ for (var object : result.objects()) {
 }
 ```
 
+When _ingetsting_ data, Java records can be used to represent nested object properties:
+
+```java
+record MusicVideo(@Property("link") String url, long runtimeSeconds) {}
+
+songs.data.insert(Map.of(
+    "title", "Billie Jean",
+    "musicVideo", new MusicVideo("https://youtube.com/billijean", 294L),
+));
+```
+
 We want to stress that this ORM's focus is on improving type-safety around object properties and simplifying serialization/deserialization. It is intentionally kept minimal and as such has the following limitations:
 
 - **Does not support BLOB properties.** On the wire, blob properties are represented as base64-encoded strings, and both logically map to the Java's `String`. Presently there isn't a good way for the client to deduce which property type should be created, so it always maps `Sting -> TEXT`.
 - **Limited configuration options.** Vector indices, replication, multi-tenancy, and such need to be configured via a tucked builder in `.create(..., here -> here)`.
+- **Cannot include nested objects.** Java records can be used as nested properties in a `Map`, but cannot include nested properties themselves.
 - **Does not support cross-references.** Properties and Cross-References are conceptually and "physically" separated in Weaviate' client libraries, so doing something like in the snippet below is not supported.
 
 ```java