wpgraphql_register_custom_mutation_inputs.php

wpgraphql_register_custom_mutation_inputs.php

<?php
  $graphql_singular_name = 'Post';
  $graphql_field_type = 'String';
  $field_config = [
    'name' => 'The human readable ACF field name',
    'graphql_name' => 'The GraphQL field name, eg first_name',
  ];
  
  add_filter('graphql_input_fields', function ($fields, $type_name) use ($graphql_singular_name, $graphql_field_type, $field_config) {
      if ($type_name === "Create{$graphql_singular_name}Input" || $type_name === "Update{$graphql_singular_name}Input") {
          // add field as input untested with non-scalar fields
          ['name' => $name, 'graphql_name' => $graphql_name] = $field_config;
          $fields[$graphql_name] = [
              'type'          => $graphql_field_type,
              'description'   => $name,
          ];
      }
      return $fields;
  }, 10, 2);

  add_action('graphql_post_object_mutation_update_additional_data', function (int $post_id, array $input) use ($field_config) {
      // update the meta value
      ['id' => $id, 'graphql_name' => $graphql_name] = $field_config;
      rwmb_set_meta($post_id, $id, $input[$graphql_name]);
  }, 10, 3);