The REST API lets you access raw FacetWP data, which you could use to build custom applications.

Enabling the API

By default, the FacetWP REST API is disabled. To enable it, use this hook:

How to use custom PHP code?
PHP code can be added to your (child) theme's functions.php file. Alternatively, you can use the Custom Hooks add-on, or a code snippets plugin. More info
add_filter( 'facetwp_api_can_access', function( $boolean ) {
  return current_user_can( 'manage_options' );
});

Endpoint URL

/wp-json/facetwp/v1/fetch

This endpoint expects a POST request with 1 parameter: data. This parameter should be a string (a stringified JSON object).

Example

Let’s retrieve cars with make = audi, and also grab choices for the vehicle_type facet.

Here’s the request JSON, before getting stringified:

How to use custom JavaScript code?
JavaScript code can be placed in your (child) theme's main JavaScript file. Alternatively, you can add it manually between <script> tags in the <head> section of your (child) theme's header.php file. You can also load it with a hook in your (child) theme's functions.php file, or in the Custom Hooks add-on. To load the code only on pages with facets, use the facetwp_scripts hook. To load it on all pages, use wp_head or wp_footer. Or you can use a code snippets plugin. More info
var request_data = {
  'data': {
    'facets': {
      'make': ['audi'],
      'vehicle_type': []
    },
    'query_args': {
      'post_type': 'cars',
      'posts_per_page': 4,
      'paged': 1
    }
  }
};

Here’s the request using JavaScript’s fetch() method:

How to use custom JavaScript code?
JavaScript code can be placed in your (child) theme's main JavaScript file. Alternatively, you can add it manually between <script> tags in the <head> section of your (child) theme's header.php file. You can also load it with a hook in your (child) theme's functions.php file, or in the Custom Hooks add-on. To load the code only on pages with facets, use the facetwp_scripts hook. To load it on all pages, use wp_head or wp_footer. Or you can use a code snippets plugin. More info
var response = fetch('https://yoursite.com/wp-json/facetwp/v1/fetch', {
  'method': 'POST',
  'headers': {
    'Content-Type': 'application/json',
    'Authorization': 'Basic ' + btoa('username:password') // base64-encoded
  },
  'body': JSON.stringify(request_data)
})
.then(response => response.json())
.then(result => console.log(result));

Response data

{
  "results":[
    1,
    2,
    3,
    4
  ],
  "facets":{
    "make":{
      "name":"make",
      "label":"Make",
      "type":"checkboxes",
      "selected":[
        "audi"
      ],
      "choices":[
        {
          "value":"audi",
          "label":"Audi",
          "depth":0,
          "count":20
        }
      ]
    },
    "vehicle_type":{
      "name":"vehicle_type",
      "label":"Vehicle Type",
      "type":"checkboxes",
      "selected":[

      ],
      "choices":[
        {
          "value":"car",
          "label":"Car",
          "depth":0,
          "count":17
        },
        {
          "value":"suv",
          "label":"SUV",
          "depth":0,
          "count":3
        },
        {
          "value":"minivan",
          "label":"Minivan",
          "depth":0,
          "count":0
        },
        {
          "value":"truck",
          "label":"Truck",
          "depth":0,
          "count":0
        },
        {
          "value":"van",
          "label":"Van",
          "depth":0,
          "count":0
        }
      ]
    }
  },
  "pager":{
    "page":1,
    "per_page":4,
    "total_rows":20,
    "total_pages":5
  }
}

Trigger the indexer programmatically

You may need to trigger the indexer programmatically if posts aren’t saved via the normal /wp-admin/.

The second code sample on the above-linked section shows how to force FacetWP to re-index a specific post.

See also