Nuxeo Server

Tagging

Updated: December 19, 2019

The tags are either categorizing the content of the document (labels like document_management, ECM, complex_Web_application, etc., can be thought as tags for Nuxeo), or they reflect the user feeling (great, user_friendly, versatile, etc.).

The tag service uses two important concepts: a tag object, and a tagging action. Both are represented as Nuxeo documents.

A tagging action is a link between a given document and a tag, and belongs to a given user. A tag holds a label that does not contain any:

  • space
  • slash
  • backslash
  • percent
  • quote

Characters will be removed by service.

Functional Overview

Tag Service Architecture

The following document types are defined by the tag service.

A Tag is a document type representing the tag itself (but not its association to specific documents). It contains the usual dublincore schema, and in addition has a specific tag schema containing a tag:label string field.

A Tagging is a relation type representing the action of tagging a given document with a tag. (A relation type is a document type extending the default Relation document type; it works like a normal document type except that it's not found by NXQL queries on Document). The important fields of a Tagging document are relation:source which is the document id, relation:target which is the tag id, and dc:creator which is the user doing the tagging action.

Both Tag and Tagging documents managed by the tag service are unfiled, which means that they don't have a parent folder. They are therefore not visible in the normal tree of documents; only queries can find them. In addition they don't have any ACLs set on them, which means that only a superuser (and the tag service internal code) can access them.

Tag Service Features

The tag service is accessed through the TagService interface.

The tag service allows you to:

  • Tag and untag a document
  • Get all the tags for a document
  • Get all the documents for a tag
  • Get the tag cloud for a set of documents
  • Get suggested tags for a given tag prefix

Tags, Versions and Proxies

The tags are duplicated:

  • From the live document when creating a version
  • From a version when creating a proxy

When restoring a version, the tags on the live document are also restored from the ones on the version.

Tags can be added and removed independently on live documents, versions and proxies: a tag added on a live document won't be added on all its versions, but only on the versions that will be created after. The same behavior is applied for proxies.

The logic for the above is in the TaggedVersionListener listener.

Disabling Tags on Versions and Proxies

To disable the duplication of tags on versions and proxies, the TaggedVersionListener may be disabled with the following contribution:

<require>org.nuxeo.ecm.platform.tag.service.listener</require>
<extension target="org.nuxeo.ecm.core.event.EventServiceComponent" point="listener">
  <listener name="taggedVersionListener" enabled="false" />
</extension>

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