Implementation:Datahub project Datahub HasTags Mixin

Knowledge Sources	Datahub_project_Datahub
Domains	Java_SDK, Metadata_Management
Last Updated	2026-02-10 00:00 GMT

Overview

HasTags is a Java mixin interface providing tag operations (add, remove, set, get) for any DataHub entity that supports the globalTags aspect, using a self-bounded generic pattern for fluent method chaining.

Description

The HasTags<T> interface uses Java default methods to inject tag management behavior into entity classes without requiring code duplication. It is parameterized with a self-bounded generic T extends Entity & HasTags<T> to ensure that fluent setter methods return the concrete entity type.

Key characteristics:

• Patch-based add/remove: addTag() and removeTag() use an accumulated GlobalTagsPatchBuilder instance, retrieved and registered via the entity's getPatchBuilder() and registerPatchBuilder() methods. Multiple tag operations are batched into a single MCP.
• Full replacement set: setTags() creates a complete GlobalTags aspect with a TagAssociationArray and emits it as a MetadataChangeProposalWrapper with UPSERT change type. This replaces all existing tags.
• Lazy-loaded read: getTags() reads the GlobalTags aspect from the entity's cache via getAspectLazy().
• URN normalization: Tag strings are automatically prefixed with "urn:li:tag:" if not already in URN format. For example, addTag("pii") is equivalent to addTag("urn:li:tag:pii").
• Server compatibility: Includes a static transformPatchToFullAspect() method that converts patch MCPs to full aspect replacement MCPs via read-modify-write for compatibility with older DataHub servers (<= v1.3.0). The applyPatchOperations() method parses JSON Patch arrays and applies ADD/REMOVE operations on the /tags/ path.

Entities implementing this interface: Chart, Container, Dashboard, DataFlow, DataJob, MLModel, MLModelGroup, and Dataset.

Usage

Any entity class extending Entity that needs tag support should implement HasTags<MyEntity>. The interface provides all tag operations via default methods, requiring no additional implementation in the entity class itself.

Code Reference

Source Location

• Repository: Datahub_project_Datahub
• File: metadata-integration/java/datahub-client/src/main/java/datahub/client/v2/entity/HasTags.java

Signature

public interface HasTags<T extends Entity & HasTags<T>> {

    // Add operations (patch-based, accumulated)
    default T addTag(String tagUrn);
    default T addTag(TagUrn tagUrn);

    // Remove operations (patch-based, accumulated)
    default T removeTag(String tagUrn);
    default T removeTag(TagUrn tagUrn);

    // Full replacement
    default T setTags(List<String> tagUrns);

    // Read
    default List<TagAssociation> getTags();

    // Server compatibility (static)
    static MetadataChangeProposal transformPatchToFullAspect(
        MetadataChangeProposal patch, EntityClient client)
        throws IOException, ExecutionException, InterruptedException;

    // Patch application (package-private static)
    static GlobalTags applyPatchOperations(GlobalTags current, MetadataChangeProposal patch)
        throws IOException;
}

Import

import datahub.client.v2.entity.HasTags;

I/O Contract

Inputs

Method	Parameter	Type	Description
addTag	tagUrn	String or TagUrn	Tag URN or short name (auto-prefixed with urn:li:tag:)
removeTag	tagUrn	String or TagUrn	Tag URN to remove
setTags	tagUrns	List<String>	Complete list of tag URNs to set (replaces all)

Outputs

Method	Return Type	Description
addTag / removeTag / setTags	T (concrete entity type)	Returns this for fluent chaining
getTags	List<TagAssociation>	List of tag associations, or null if no tags
transformPatchToFullAspect	MetadataChangeProposal	Full UPSERT MCP with applied tag changes

Usage Examples

// Using HasTags via a concrete entity
Dataset dataset = Dataset.builder()
    .platform("snowflake")
    .name("my_table")
    .build();

// Add tags (short name auto-prefixed)
dataset.addTag("pii");
dataset.addTag("urn:li:tag:sensitive");

// Remove a tag
dataset.removeTag("deprecated");

// Replace all tags
dataset.setTags(List.of("production", "verified", "urn:li:tag:tier1"));

// Read tags
List<TagAssociation> tags = dataset.getTags();

// Implementing HasTags in a custom entity
public class MyEntity extends Entity implements HasTags<MyEntity> {
    // All tag operations are provided by default methods
    // No additional implementation needed
}

Related Pages

• Environment:Datahub_project_Datahub_Java_17_Backend_Environment