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Add FlexObjectConverter.
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6 files changed

+403
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‎objectbox-java/src/main/java/io/objectbox/converter/FlexObjectConverter.java

Lines changed: 286 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,286 @@
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package io.objectbox.converter;
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import io.objectbox.flatbuffers.ArrayReadWriteBuf;
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import io.objectbox.flatbuffers.FlexBuffers;
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import io.objectbox.flatbuffers.FlexBuffersBuilder;
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import java.lang.reflect.Field;
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import java.nio.ByteBuffer;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import java.util.concurrent.atomic.AtomicReference;
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/**
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* Converts between {@link Object} properties and byte arrays using FlexBuffers.
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* <p>
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* Types are limited to those supported by FlexBuffers, including that map keys must be {@link String}.
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* <p>
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* Regardless of the stored type, integers are restored as {@link Long} if the value does not fit {@link Integer},
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* otherwise as {@link Integer}. So e.g. when storing a {@link Long} value of {@code 1L}, the value restored from the
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* database will be of type {@link Integer}.
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* <p>
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* Values of type {@link Float} are always restored as {@link Double}.
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* Cast to {@link Float} to obtain the original value.
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*/
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public class FlexObjectConverter implements PropertyConverter<Object, byte[]> {
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private static final AtomicReference<FlexBuffersBuilder> cachedBuilder = new AtomicReference<>();
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@Override
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public byte[] convertToDatabaseValue(Object value) {
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if (value == null) return null;
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FlexBuffersBuilder builder = cachedBuilder.getAndSet(null);
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if (builder == null) {
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// Note: BUILDER_FLAG_SHARE_KEYS_AND_STRINGS is as fast as no flags for small maps/strings
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// and faster for larger maps/strings. BUILDER_FLAG_SHARE_STRINGS is always slower.
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builder = new FlexBuffersBuilder(
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new ArrayReadWriteBuf(512),
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FlexBuffersBuilder.BUILDER_FLAG_SHARE_KEYS_AND_STRINGS
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);
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}
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addValue(builder, value);
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ByteBuffer buffer = builder.finish();
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byte[] out = new byte[buffer.limit()];
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buffer.get(out);
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// Cache if builder does not consume too much memory
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if (buffer.limit() <= 256 * 1024) {
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builder.clear();
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cachedBuilder.getAndSet(builder);
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}
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return out;
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}
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private void addValue(FlexBuffersBuilder builder, Object value) {
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if (value instanceof Map) {
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//noinspection unchecked
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addMap(builder, null, (Map<Object, Object>) value);
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} else if (value instanceof List) {
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//noinspection unchecked
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addVector(builder, null, (List<Object>) value);
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} else if (value instanceof String) {
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builder.putString((String) value);
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} else if (value instanceof Boolean) {
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builder.putBoolean((Boolean) value);
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} else if (value instanceof Integer) {
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builder.putInt((Integer) value);
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} else if (value instanceof Long) {
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builder.putInt((Long) value);
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} else if (value instanceof Float) {
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builder.putFloat((Float) value);
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} else if (value instanceof Double) {
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builder.putFloat((Double) value);
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} else if (value instanceof byte[]) {
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builder.putBlob((byte[]) value);
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} else {
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throw new IllegalArgumentException(
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"Values of this type are not supported: " + value.getClass().getSimpleName());
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}
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}
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private void addMap(FlexBuffersBuilder builder, String mapKey, Map<Object, Object> map) {
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int mapStart = builder.startMap();
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for (Map.Entry<Object, Object> entry : map.entrySet()) {
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Object value = entry.getValue();
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if (entry.getKey() == null || value == null) {
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throw new IllegalArgumentException("Map keys or values must not be null");
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}
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String key = entry.getKey().toString();
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if (value instanceof Map) {
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//noinspection unchecked
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addMap(builder, key, (Map<Object, Object>) value);
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} else if (value instanceof List) {
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//noinspection unchecked
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addVector(builder, key, (List<Object>) value);
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} else if (value instanceof String) {
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builder.putString(key, (String) value);
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} else if (value instanceof Boolean) {
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builder.putBoolean(key, (Boolean) value);
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} else if (value instanceof Integer) {
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builder.putInt(key, (Integer) value);
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} else if (value instanceof Long) {
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builder.putInt(key, (Long) value);
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} else if (value instanceof Float) {
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builder.putFloat(key, (Float) value);
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} else if (value instanceof Double) {
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builder.putFloat(key, (Double) value);
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} else if (value instanceof byte[]) {
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builder.putBlob(key, (byte[]) value);
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} else {
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throw new IllegalArgumentException(
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"Map values of this type are not supported: " + value.getClass().getSimpleName());
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}
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}
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builder.endMap(mapKey, mapStart);
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}
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private void addVector(FlexBuffersBuilder builder, String vectorKey, List<Object> list) {
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int vectorStart = builder.startVector();
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for (Object item : list) {
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if (item instanceof Map) {
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//noinspection unchecked
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addMap(builder, null, (Map<Object, Object>) item);
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} else if (item instanceof List) {
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//noinspection unchecked
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addVector(builder, null, (List<Object>) item);
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} else if (item instanceof String) {
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builder.putString((String) item);
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} else if (item instanceof Boolean) {
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builder.putBoolean((Boolean) item);
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} else if (item instanceof Integer) {
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builder.putInt((Integer) item);
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} else if (item instanceof Long) {
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builder.putInt((Long) item);
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} else if (item instanceof Float) {
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builder.putFloat((Float) item);
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} else if (item instanceof Double) {
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builder.putFloat((Double) item);
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} else if (item instanceof byte[]) {
150+
builder.putBlob((byte[]) item);
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} else {
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throw new IllegalArgumentException(
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"List values of this type are not supported: " + item.getClass().getSimpleName());
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}
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}
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builder.endVector(vectorKey, vectorStart, false, false);
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}
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@Override
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public Object convertToEntityProperty(byte[] databaseValue) {
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if (databaseValue == null) return null;
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FlexBuffers.Reference value = FlexBuffers.getRoot(new ArrayReadWriteBuf(databaseValue, databaseValue.length));
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if (value.isMap()) {
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return buildMap(value.asMap());
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} else if (value.isVector()) {
168+
return buildList(value.asVector());
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} else if (value.isString()) {
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return value.asString();
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} else if (value.isBoolean()) {
172+
return value.asBoolean();
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} else if (value.isInt()) {
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if (shouldRestoreAsLong(value)) {
175+
return value.asLong();
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} else {
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return value.asInt();
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}
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} else if (value.isFloat()) {
180+
// Always return as double; if original was float consumer can cast to obtain original value.
181+
return value.asFloat();
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} else if (value.isBlob()) {
183+
return value.asBlob().getBytes();
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} else {
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throw new IllegalArgumentException("FlexBuffers type is not supported: " + value.getType());
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}
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}
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/**
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* Returns true if the width in bytes stored in the private parentWidth field of FlexBuffers.Reference is 8.
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* Note: FlexBuffers stores all items in a map/vector using the size of the widest item. However,
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* an item's size is only as wide as needed, e.g. a 64-bit integer (Java Long, 8 bytes) will be
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* reduced to 1 byte if it does not exceed its value range.
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*/
195+
private boolean shouldRestoreAsLong(FlexBuffers.Reference reference) {
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try {
197+
Field parentWidthF = reference.getClass().getDeclaredField("parentWidth");
198+
parentWidthF.setAccessible(true);
199+
return (int) parentWidthF.get(reference) == 8;
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} catch (Exception e) {
201+
// If thrown, it is likely the FlexBuffers API has changed and the above should be updated.
202+
throw new RuntimeException("FlexMapConverter could not determine FlexBuffers integer bit width.", e);
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}
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}
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private Map<Object, Object> buildMap(FlexBuffers.Map map) {
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// As recommended by docs, iterate keys and values vectors in parallel to avoid binary search of key vector.
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int entryCount = map.size();
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FlexBuffers.KeyVector keys = map.keys();
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FlexBuffers.Vector values = map.values();
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// Note: avoid HashMap re-hashing by choosing large enough initial capacity.
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// From docs: If the initial capacity is greater than the maximum number of entries divided by the load factor,
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// no rehash operations will ever occur.
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// So set initial capacity based on default load factor 0.75 accordingly.
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Map<Object, Object> resultMap = new HashMap<>((int) (entryCount / 0.75 + 1));
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for (int i = 0; i < entryCount; i++) {
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String key = keys.get(i).toString();
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FlexBuffers.Reference value = values.get(i);
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if (value.isMap()) {
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resultMap.put(key, buildMap(value.asMap()));
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} else if (value.isVector()) {
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resultMap.put(key, buildList(value.asVector()));
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} else if (value.isString()) {
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resultMap.put(key, value.asString());
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} else if (value.isBoolean()) {
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resultMap.put(key, value.asBoolean());
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} else if (value.isInt()) {
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if (shouldRestoreAsLong(value)) {
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resultMap.put(key, value.asLong());
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} else {
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resultMap.put(key, value.asInt());
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}
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} else if (value.isFloat()) {
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// Always return as double; if original was float consumer can cast to obtain original value.
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resultMap.put(key, value.asFloat());
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} else if (value.isBlob()) {
237+
resultMap.put(key, value.asBlob().getBytes());
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} else {
239+
throw new IllegalArgumentException(
240+
"Map values of this type are not supported: " + value.getClass().getSimpleName());
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}
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}
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return resultMap;
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}
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private List<Object> buildList(FlexBuffers.Vector vector) {
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int itemCount = vector.size();
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List<Object> list = new ArrayList<>(itemCount);
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// FlexBuffers uses the byte width of the biggest item to size all items, so only need to check the first.
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Boolean shouldRestoreAsLong = null;
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for (int i = 0; i < itemCount; i++) {
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FlexBuffers.Reference item = vector.get(i);
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if (item.isMap()) {
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list.add(buildMap(item.asMap()));
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} else if (item.isVector()) {
259+
list.add(buildList(item.asVector()));
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} else if (item.isString()) {
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list.add(item.asString());
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} else if (item.isBoolean()) {
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list.add(item.asBoolean());
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} else if (item.isInt()) {
265+
if (shouldRestoreAsLong == null) {
266+
shouldRestoreAsLong = shouldRestoreAsLong(item);
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}
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if (shouldRestoreAsLong) {
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list.add(item.asLong());
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} else {
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list.add(item.asInt());
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}
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} else if (item.isFloat()) {
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// Always return as double; if original was float consumer can cast to obtain original value.
275+
list.add(item.asFloat());
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} else if (item.isBlob()) {
277+
list.add(item.asBlob().getBytes());
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} else {
279+
throw new IllegalArgumentException(
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"List values of this type are not supported: " + item.getClass().getSimpleName());
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}
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}
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return list;
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}
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}

‎tests/objectbox-java-test/src/main/java/io/objectbox/TestEntity.java

Lines changed: 15 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -52,6 +52,7 @@ public class TestEntity {
5252
/** In "real" entity would be annotated with @Unsigned. */
5353
private long simpleLongU;
5454
private Map<String, Object> stringObjectMap;
55+
private Object flexProperty;
5556

5657
transient boolean noArgsConstructorCalled;
5758

@@ -66,7 +67,8 @@ public TestEntity(long id) {
6667
public TestEntity(long id, boolean simpleBoolean, byte simpleByte, short simpleShort, int simpleInt,
6768
long simpleLong, float simpleFloat, double simpleDouble, String simpleString,
6869
byte[] simpleByteArray, String[] simpleStringArray, List<String> simpleStringList,
69-
short simpleShortU, int simpleIntU, long simpleLongU, Map<String, Object> stringObjectMap) {
70+
short simpleShortU, int simpleIntU, long simpleLongU, Map<String, Object> stringObjectMap,
71+
Object flexProperty) {
7072
this.id = id;
7173
this.simpleBoolean = simpleBoolean;
7274
this.simpleByte = simpleByte;
@@ -83,6 +85,7 @@ public TestEntity(long id, boolean simpleBoolean, byte simpleByte, short simpleS
8385
this.simpleIntU = simpleIntU;
8486
this.simpleLongU = simpleLongU;
8587
this.stringObjectMap = stringObjectMap;
88+
this.flexProperty = flexProperty;
8689
if (STRING_VALUE_THROW_IN_CONSTRUCTOR.equals(simpleString)) {
8790
throw new RuntimeException(EXCEPTION_IN_CONSTRUCTOR_MESSAGE);
8891
}
@@ -226,6 +229,16 @@ public TestEntity setStringObjectMap(Map<String, Object> stringObjectMap) {
226229
return this;
227230
}
228231

232+
@Nullable
233+
public Object getFlexProperty() {
234+
return flexProperty;
235+
}
236+
237+
public TestEntity setFlexProperty(@Nullable Object flexProperty) {
238+
this.flexProperty = flexProperty;
239+
return this;
240+
}
241+
229242
@Override
230243
public String toString() {
231244
return "TestEntity{" +
@@ -245,6 +258,7 @@ public String toString() {
245258
", simpleIntU=" + simpleIntU +
246259
", simpleLongU=" + simpleLongU +
247260
", stringObjectMap=" + stringObjectMap +
261+
", flexProperty=" + flexProperty +
248262
", noArgsConstructorCalled=" + noArgsConstructorCalled +
249263
'}';
250264
}

‎tests/objectbox-java-test/src/main/java/io/objectbox/TestEntityCursor.java

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -17,6 +17,7 @@
1717
package io.objectbox;
1818

1919
import io.objectbox.annotation.apihint.Internal;
20+
import io.objectbox.converter.FlexObjectConverter;
2021
import io.objectbox.converter.StringFlexMapConverter;
2122
import io.objectbox.internal.CursorFactory;
2223

@@ -45,6 +46,7 @@ public Cursor<TestEntity> createCursor(io.objectbox.Transaction tx, long cursorH
4546
private static final TestEntity_.TestEntityIdGetter ID_GETTER = TestEntity_.__ID_GETTER;
4647

4748
private final StringFlexMapConverter stringObjectMapConverter = new StringFlexMapConverter();
49+
private final FlexObjectConverter flexPropertyConverter = new FlexObjectConverter();
4850

4951
private final static int __ID_simpleBoolean = TestEntity_.simpleBoolean.id;
5052
private final static int __ID_simpleByte = TestEntity_.simpleByte.id;
@@ -61,6 +63,7 @@ public Cursor<TestEntity> createCursor(io.objectbox.Transaction tx, long cursorH
6163
private final static int __ID_simpleIntU = TestEntity_.simpleIntU.id;
6264
private final static int __ID_simpleLongU = TestEntity_.simpleLongU.id;
6365
private final static int __ID_stringObjectMap = TestEntity_.stringObjectMap.id;
66+
private final static int __ID_flexProperty = TestEntity_.flexProperty.id;
6467

6568
public TestEntityCursor(io.objectbox.Transaction tx, long cursor, BoxStore boxStore) {
6669
super(tx, cursor, TestEntity_.__INSTANCE, boxStore);
@@ -96,12 +99,14 @@ public final long put(TestEntity entity) {
9699
int __id9 = simpleByteArray != null ? __ID_simpleByteArray : 0;
97100
Map stringObjectMap = entity.getStringObjectMap();
98101
int __id15 = stringObjectMap != null ? __ID_stringObjectMap : 0;
102+
Object flexProperty = entity.getFlexProperty();
103+
int __id16 = flexProperty != null ? __ID_flexProperty : 0;
99104

100105
collect430000(cursor, 0, 0,
101106
__id8, simpleString, 0, null,
102107
0, null, 0, null,
103108
__id9, simpleByteArray, __id15, __id15 != 0 ? stringObjectMapConverter.convertToDatabaseValue(stringObjectMap) : null,
104-
0, null);
109+
__id16, __id16 != 0 ? flexPropertyConverter.convertToDatabaseValue(flexProperty) : null);
105110

106111
collect313311(cursor, 0, 0,
107112
0, null, 0, null,

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