Developer Documentation

Search

The Search module provides a mirrored Elasticsearch index of all CMS content that is optimized for search relevance, speed and accuracy. This operates at a higher level than the primary datastore (MySQL) and is the recommended solution for searching.

The benefits of using Elasticsearch over MySQL search queries include:

  • Speed
  • Advanced text analysis
    • Removing HTML
    • Language dependent word stemming and stopwords
    • Language dependent tokenisation
  • Configurable relevancy scores
  • Fuzzy matching
  • Synonyms
  • Aggregations for faceted search and statistics

The default Search index and related functionality is provided by the ElasticPress plugin and the multilingual support is derived from the WordPress.com Elasticsearch library.

If you do not wish to use the search module it can be deactivated via your config:

{
    "extra": {
        "altis": {
            "modules": {
                "search": {
                    "enabled": false
                }
            }
        }
    }
}

Note: turning this module off does not remove the Elasticsearch server. This can still be used for Native Analytics and any custom use cases.

Content that is indexed in the search index by default:

  • Posts
  • Pages
  • Media
  • Custom Post Types (registered with show_in_search or public)
  • Post Meta
  • Post Terms
  • Post Author
  • Users
  • User Meta
  • Terms
  • Term Meta

When used in conjunction with the Media Rekognition feature, all images are processed for automatic keyword detection and stored in the search index too.

CMS Query Integration

The method for determining whether CMS queries are handled by Elasticsearch or MySQL uses sensible defaults, but can also be controlled in more granular ways through code. Special handling is required for supporting partial search terms common in autosuggest or "typeahead" interfaces.

Find out how to control Elasticsearch query integration and how to use autosuggest search here.

Search Configuration

The default search behavior can be tuned to allow for stricter or more permissive matching, as well as enabling advanced search query capabilities such as using quoted strings for exact matches. You can also tune the relevancy of specific fields and how fuzzy matching works.

See Search Configuration for full details.

Custom User Dictionaries

A subset of search configuration is the ability to upload custom user dictionaries for adding synonyms, stop words and custom text analysis for Japanese to further tune and improve search results.

Document Indexing

All documents that are uploaded to the media library can also be parsed and indexed. For example, if you upload a PDF file, the PDF content will be read and included in the search index. Searches for keywords and phrases that are included in the document will be then be included in search results.

The following document types are parsed and their content is added to the search index:

  • PDF
  • PPT
  • PPTX
  • XLS
  • XLSX
  • DOC
  • DOCX

To enable the indexing of document content, set the modules.search.index-documents setting to true.

Search Index Modification

It is also possible to modify the specific fields stored for each post to provide extra search data that is not included by default. See Search Index Modification for details.

Using Elasticsearch

Elasticsearch is used to provide the search index, as such as a developer you can make direct use of Elasticsearch for advanced feature development. See Using Elasticsearch for details.

Additional Configuration Options

The following options can be enabled/disabled via the search configuration.

  • "related-posts": true|false (default)
  • "facets": true|false|['match-type' => "all" (default)|...]
  • "woocommerce": true|false (default)
  • "autosuggest": true|false (default)

Related Posts

To find related posts leveraging Elastic Search use the ep_find_related() function. The function requires a single parameter ( $post_id ) with another optional parameter ( $return ). The $post_id will be used to find the posts that are related to it, with $return specifying the number of related posts to return, which defaults to 5.

If an out of the box solution is desired, a widget ElasticPress - Related Posts is created that can be added to your site's sidebar. In order for the widget to work correctly it needs to be added to the sidebar which will be displayed for a single post.

Facets

Facets are a feature in ElasticPress which add control to filter content by one or more taxonomies. A widget can be added so when viewing a content list (archive), the taxonomy and all of its terms will be displayed. This will allow a vistors to further filter content.

Depending on the configuration specified for facets, if the match-type property is set to any, it will force the results to match any selected taxonomy term. If set to all, it will match to results with all of the selected terms.

Search Form Auto Suggest

This feature enhances search forms on the website to show a dropdown list of suggestions as users type.