Sergiy Dzysyak

This plugin provides simple REST API for the popular search <a href="https://wordpress.org/" title="Your favorite blogging software" rel="ugc">WordPress</a> search engine – <a href="https://wordpress.org/plugins/relevanssi/" title="A Better Search" rel="ugc">Relevanssi</a>.
As far as this plugin provides API for the Relevanssi plugin, it should be installed.
Key features
<ul>
<li>Search through posts of a certain type. By default all types.</li>
<li>Results in pagination and optional.</li>
<li>Sets X-WP-Total header with a total number of records, the same way as the default search API does.</li>
<li>Sets X-WP-TotalPages header with a total number of pages, the same way as the default search API does.</li>
<li>Multilingual websites support. Both WPML and Polylang are supported, but not tested well, so let me know if you will find any problems.</li>
<li>Taxonomy filters are supported now. Some features may be missed, so feel free to report them.</li>
<li>Ordering option added. It is also possible to order by meta_key/meta_value/meta_value_num. </li>
</ul>
Brief usage examples
<ul>
<li>https://[your domain]/wp-json/relevanssi/v1/search?keyword=query</li>
<li>https://[your domain]/wp-json/relevanssi/v1/search?keyword=query&per_page=5</li>
<li>https://[your domain]/wp-json/relevanssi/v1/search?keyword=query&per_page=5&page=2</li>
</ul>
Define post type:
<ul>
<li>https://[your domain]/wp-json/relevanssi/v1/search?keyword=query&per_page=5&page=2&type=post</li>
</ul>
Filter by taxonomy/taxonomies:
<ul>
<li>https://[your domain]/wp-json/relevanssi/v1/search?keyword=test&tax_query[0][taxonomy]=category&tax_query[0][field]=id&tax_query[0][terms]=3</li>
<li>https://[your domain]/wp-json/relevanssi/v1/search?keyword=test&tax_query[relation]=AND&tax_query[0][taxonomy]=category&tax_query[0][field]=id&tax_query[0][terms]=3&tax_query[1][taxonomy]=category&tax_query[1][field]=id&tax_query[1][terms]=2</li>
</ul>
Exclude category via taxonomies:
<ul>
<li>https://[your domain]/wp-json/relevanssi/v1/search?keyword=test&tax_query[0][taxonomy]=category&tax_query[0][field]=id&tax_query[0][terms]=3&tax_query[0][operator]=NOT IN</li>
</ul>
For multilingual websites (WPML & Polylang):
<ul>
<li>
https://[your domain]/wp-json/relevanssi/v1/search?keyword=query&lng=en
<ul>
<li>Results in order:</li>
</ul>
</li>
<li>
https://[your domain]/wp-json/relevanssi/v1/search?keyword=test&type=post&orderby=modified&order=DESC
</li>
<li>https://[your domain]/wp-json/relevanssi/v1/search?keyword=test&type=post&orderby=modified&order=ASC</li>
<li>https://[your domain]/wp-json/relevanssi/v1/search?keyword=test&type=post&meta_key=some_key&orderby=meta_value|meta_value_num&order=ASC</li>
</ul>
Demo website
You can try the plugin on our demo website http://demo.erlycoder.com/demo1/. For example, you can try the following request:
Basic: 
<a href="http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test" rel="nofollow ugc">http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test</a>
Order posts by modification time: 
<a href="http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test&type=post&orderby=modified&order=DESC" rel="nofollow ugc">http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test&type=post&orderby=modified&order=DESC</a> 
<a href="http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test&type=post&orderby=modified&order=ASC" rel="nofollow ugc">http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test&type=post&orderby=modified&order=ASC</a>
Filter posts by taxonomy (one single category): 
<a href="http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test&tax_query[0][taxonomy]=category&tax_query[0][field]=id&tax_query[0][terms]=3" rel="nofollow ugc">http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test&tax_query[0][taxonomy]=category&tax_query[0][field]=id&tax_query[0][terms]=3</a>
Filter posts by taxonomy (exclude category): 
[http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test&tax_query[0][taxonomy]=category&tax_query[0][field]=id&tax_query[0][terms]=3&tax_query[0][operator]=NOT IN](http://demo.erlycoder.com/demo1/wp-json/relevanssi/v1/search?keyword=test&tax_query[0][taxonomy]=category&tax_query[0][field]=id&tax_query[0][terms]=3&tax_query[0][operator]=NOT IN)

REST API for Relevanssi

Nice and simple plugin

The plugin provides a REST API endpoint for the Relevanssi search plugin.

toddhalfpenny

Dashboard Widgets for Relevanssi Search data. Of course requires the wonderful Relevanssi plugin too.

Relevanssi Dashboard

Dashboard Widgets for Relevanssi Search data. Of course requires the wonderful Relevanssi plugin too.

REST API for Relevanssi vs Relevanssi Dashboard