FacetWP has two API endpoints: the /facetwp/v1/fetch and the /facetwp/v1/refresh endpoint. The /facetwp/v1/fetch endpoint lets you query raw FacetWP data, with which you can build custom applications. The /facetwp/v1/refresh endpoint is used by FacetWP itself in the front-end, for filtering.

By default, the fetch endpoint is disabled. The /facetwp/v1/refresh endpoint is always open.

Enable the fetch API endpoint

By default, the REST API /facetwp/v1/fetch endpoint is disabled. To enable it, use this hook in your (child) theme’s functions.php:

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' );
});

Fetch endpoint URL

/wp-json/facetwp/v1/fetch

The /facetwp/v1/fetch 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