Support modifying data attachments using the /data command

fabric-data-attachment-api-v1/src/main/java/net/fabricmc/fabric/impl/attachment/DataAccessorHandler.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.impl.attachment;
+
+import java.util.IdentityHashMap;
+import java.util.Map;
+
+import net.minecraft.world.level.storage.ValueInput;
+
+import net.fabricmc.fabric.api.attachment.v1.AttachmentTarget;
+import net.fabricmc.fabric.api.attachment.v1.AttachmentType;
+
+/**
+ * Replacement logic to handle applying attachments when using the /data command.
+ * This applies the changes using the high level APIs, ensuring that the changes are correctly synced to the client.
+ */
+public class DataAccessorHandler {
+	public static ScopedValue<Void> APPLYING_DATA_CHANGE = ScopedValue.newInstance();
+
+	public static void applyDataChanges(AttachmentTarget target, ValueInput data, Runnable applyData) {
+		AttachmentTargetImpl targetImpl = (AttachmentTargetImpl) target;
+
+		Map<AttachmentType<?>, ?> oldAttachments = targetImpl.fabric_getAttachments();
+		ScopedValue.where(APPLYING_DATA_CHANGE, null).run(applyData);
+
+		if (oldAttachments != targetImpl.fabric_getAttachments()) {
+			throw new AssertionError("Attachment data changed during data change application.");
+		}
+
+		IdentityHashMap<AttachmentType<?>, Object> newAttachments = AttachmentSerializingImpl.deserializeAttachmentData(data);
+
+		if (oldAttachments == null && newAttachments == null) {
+			// No attachments before or after, nothing to do
+			return;
+		} else if (oldAttachments != null && (newAttachments == null || newAttachments.isEmpty())) {
+			// Clear all attachments - copy keys to avoid ConcurrentModificationException
+			oldAttachments.keySet().stream().toList().forEach(target::removeAttached);
+			return;
+		}
+
+		// Update the new attachments
+		newAttachments.forEach((attachmentType, o) -> target.setAttached((AttachmentType) attachmentType, o));
+
+		// Remove all of the removed attachments - copy keys to avoid ConcurrentModificationException
+		if (oldAttachments != null) {
+			oldAttachments.keySet().stream()
+					.filter(attachmentType -> !newAttachments.containsKey(attachmentType))
+					.toList()
+					.forEach(target::removeAttached);
+		}
+	}
+}

fabric-data-attachment-api-v1/src/main/java/net/fabricmc/fabric/mixin/attachment/AttachmentTargetsMixin.java

@@ -46,6 +46,7 @@
 import net.fabricmc.fabric.impl.attachment.AttachmentSerializingImpl;
 import net.fabricmc.fabric.impl.attachment.AttachmentTargetImpl;
 import net.fabricmc.fabric.impl.attachment.AttachmentTypeImpl;
+import net.fabricmc.fabric.impl.attachment.DataAccessorHandler;
 import net.fabricmc.fabric.impl.attachment.GlobalAttachmentsImpl;
 import net.fabricmc.fabric.impl.attachment.sync.AttachmentChange;
 import net.fabricmc.fabric.impl.attachment.sync.AttachmentSync;
@@ -137,6 +138,11 @@ public void fabric_writeAttachmentsToNbt(ValueOutput output) {
 
 	@Override
 	public void fabric_readAttachmentsFromNbt(ValueInput input) {
+		if (DataAccessorHandler.APPLYING_DATA_CHANGE.isBound()) {
+			// DataAccessorHandler handles applying data changes seperately.
+			return;
+		}
+
 		// Note on player targets: no syncing can happen here as the networkHandler is still null
 		// Instead it is done on player join (see AttachmentSync)
 		IdentityHashMap<AttachmentType<?>, Object> fromNbt = AttachmentSerializingImpl.deserializeAttachmentData(input);

fabric-data-attachment-api-v1/src/main/java/net/fabricmc/fabric/mixin/attachment/BlockDataAccessorMixin.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.mixin.attachment;
+
+import com.llamalad7.mixinextras.injector.wrapmethod.WrapMethod;
+import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.Unique;
+
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.commands.data.BlockDataAccessor;
+import net.minecraft.server.commands.data.DataAccessor;
+import net.minecraft.util.ProblemReporter;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.storage.TagValueInput;
+import net.minecraft.world.level.storage.ValueInput;
+
+import net.fabricmc.fabric.impl.attachment.DataAccessorHandler;
+
+@Mixin(BlockDataAccessor.class)
+public abstract class BlockDataAccessorMixin implements DataAccessor {
+	@Unique
+	private static final Logger LOGGER = LoggerFactory.getLogger("BlockDataAccessorMixin");
+
+	@Shadow
+	@Final
+	private BlockEntity entity;
+
+	@WrapMethod(method = "setData")
+	public void setData(CompoundTag tag, Operation<Void> original) {
+		if (entity.getLevel() == null) {
+			// The block entity is not in a level, just follow the default logic.
+			original.call(tag);
+			return;
+		}
+
+		try (ProblemReporter.ScopedCollector reporter = new ProblemReporter.ScopedCollector(LOGGER)) {
+			ValueInput data = TagValueInput.create(reporter, this.entity.getLevel().registryAccess(), tag);
+			DataAccessorHandler.applyDataChanges(this.entity, data, () -> original.call(tag));
+		}
+	}
+}

fabric-data-attachment-api-v1/src/main/java/net/fabricmc/fabric/mixin/attachment/EntityDataAccessorMixin.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.mixin.attachment;
+
+import com.llamalad7.mixinextras.injector.wrapmethod.WrapMethod;
+import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.Unique;
+
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.commands.data.DataAccessor;
+import net.minecraft.server.commands.data.EntityDataAccessor;
+import net.minecraft.util.ProblemReporter;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.level.storage.TagValueInput;
+import net.minecraft.world.level.storage.ValueInput;
+
+import net.fabricmc.fabric.impl.attachment.DataAccessorHandler;
+
+@Mixin(EntityDataAccessor.class)
+public abstract class EntityDataAccessorMixin implements DataAccessor {
+	@Unique
+	private static final Logger LOGGER = LoggerFactory.getLogger("EntityDataAccessorMixin");
+
+	@Shadow
+	@Final
+	private Entity entity;
+
+	@WrapMethod(method = "setData")
+	public void setData(CompoundTag tag, Operation<Void> original) {
+		if (entity.level() == null) {
+			// The block entity is not in a level, just follow the default logic.
+			original.call(tag);
+			return;
+		}
+
+		try (ProblemReporter.ScopedCollector reporter = new ProblemReporter.ScopedCollector(LOGGER)) {
+			ValueInput data = TagValueInput.create(reporter, this.entity.level().registryAccess(), tag);
+			DataAccessorHandler.applyDataChanges(this.entity, data, () -> original.call(tag));
+		}
+	}
+}

fabric-data-attachment-api-v1/src/main/resources/fabric-data-attachment-api-v1.mixins.json

@@ -5,11 +5,13 @@
   "mixins": [
     "AttachmentTargetsMixin",
     "BannerBlockEntityMixin",
+    "BlockDataAccessorMixin",
     "BlockEntityMixin",
     "ChunkAccessMixin",
     "ChunkHolderMixin",
     "ClientboundCustomPayloadPacketAccessor",
     "DimensionStorageFileFixMixin",
+    "EntityDataAccessorMixin",
     "EntityMixin",
     "ImposterProtoChunkMixin",
     "LevelChunkMixin",

fabric-data-attachment-api-v1/src/test/java/net/fabricmc/fabric/test/attachment/CommonAttachmentTests.java

@@ -359,7 +359,7 @@ void applyToInvalidTarget() throws AttachmentSyncException {
 	 * so testing is handled by the testmod instead.
 	 */
 
-	private static RegistryAccess mockRA() {
+	static RegistryAccess mockRA() {
 		RegistryAccess ra = mock(RegistryAccess.class);
 		when(ra.createSerializationContext(any())).thenReturn((RegistryOps<Object>) (Object) RegistryOps.create(NbtOps.INSTANCE, ra));
 		return ra;