Connecting to the GraphQL server from a client

The website can connect to the GraphQL server from any browser running JavaScript. This includes:

  • Vanilla JS in the client-side application
  • Using a framework (such as Vue or React)
  • From within a WordPress editor block

We can use any GraphQL client library to connect to the server, including:

However, there is no need for an external JavaScript library to connect to the GraphQL endpoint: simple JavaScript code will already do, as demonstrated below.

Executing queries against a GraphQL endpoint

This JavaScript code submits a query with variables to the GraphQL server, and prints the response to console.

/**
 * Replace here using either:
 * - The single endpoint's URL
 * - A custom endpoint's permalink
 */
const GRAPHQL_ENDPOINT = '{ YOUR_ENDPOINT_URL }';

(async function () {
  const limit = 3;
  const data = {
    query: `
query GetPostsWithAuthor($limit: Int) {
  posts(pagination: { limit: $limit }) {
    id
    title
    author {
      id
      name
    }
  }
}
    `,
    variables: {
      limit: `${ limit }`
    },
  };

  const response = await fetch(
    GRAPHQL_ENDPOINT,
    {
      method: 'post',
      body: JSON.stringify(data),
      headers: {
        Accept: 'application/json',
        'Content-Type': 'application/json',
        'Content-Length': data.length,
      },
      credentials: 'include',
    }
  );

  /**
   * Execute the query, and await the response
   */
  const json = await response.json();

  /**
   * Check if the query produced errors, otherwise use the results
   */
  if (json.errors) {
    console.log(JSON.stringify(json.errors));
  } else {
    console.log(JSON.stringify(json.data));
  }
})();

Executing persisted queries

Executing a persisted query has a few differences:

  • There is no need to submit a GraphQL query
  • The operation is GET, not POST
  • Variables and operation name must be added to the URL
/**
 * Replace here using:
 * - A persisted query's permalink
 */
const GRAPHQL_PERSISTED_QUERY_PERMALINK = '{ YOUR_PERSISTED_QUERY_PERMALINK }';

(async function () {
  const limit = 3;

  /**
   * If needed, add variables in the URL
   */
  const GRAPHQL_PERSISTED_QUERY = `${ GRAPHQL_PERSISTED_QUERY_PERMALINK }?limit=${ limit }`;

  const response = await fetch(
    GRAPHQL_PERSISTED_QUERY,
    {
      method: 'get',
      headers: {
        Accept: 'application/json',
        'Content-Type': 'application/json',
        'Content-Length': data.length,
      },
      credentials: 'include',
    }
  );

  const json = await response.json();
  if (json.errors) {
    console.log(JSON.stringify(json.errors));
  } else {
    console.log(JSON.stringify(json.data));
  }
})();

Sending nonce header

If you need to execute an operation including a nonce, add the X-WP-Nonce header.

Print your nonce:

<script>
const NONCE = '{ Print nonce value }' ;
</script>

Include it in the headers to fetch:

{
  headers: {
    'X-WP-Nonce': `${ NONCE }`
  }
}