Shows a WPGraphQL connection between 2 post types

wpgraphql-connection-to-another-post-type.php

/**
	 * Register the Post Type for storing the logs
	 */
	add_action( 'init', function() {
		register_post_type( 'graphql_mutation_log', [
			'label'               => __( 'Mutation Logs', 'wp-syndication-debugger' ),
			'public'              => false,
			'exclude_from_search' => true,
			'show_ui'             => current_user_can( 'manage_options' ) ? true : false,
			'show_in_graphql'     => true,
			'graphql_single_name' => 'MutationLog',
			'graphql_plural_name' => 'MutationLogs',
			'hierarchical'        => true,
		] );
	});

	/**
	 * Register custom fields on the `MutationLog` Type in the Schema
	 */
	add_action( 'graphql_register_types', function() {

		register_graphql_fields( 'MutationLog', [
			'graphQLQuery'        => [
				'type'    => 'String',
				'resolve' => function( $post ) {
					$query = get_post_meta( $post->ID, 'query', true );

					return ! empty( $query ) ? $query : null;
				}
			],
			'graphQLMutationName' => [
				'type'    => 'String',
				'resolve' => function( $post ) {
					$mutation = get_post_meta( $post->ID, 'mutation', true );

					return ! empty( $mutation ) ? $mutation : null;
				}
			],
			'currentUser'         => [
				'type'    => 'User',
				'resolve' => function( $post, $args, $context, $info ) {
					$user_id = get_post_meta( $post->ID, 'current_user', true );
					$user_id = json_decode( $user_id );

					return ! empty( $user_id ) ? DataSource::resolve_user( $user_id, $context ) : null;
				}
			],
			'graphQLVariables'    => [
				'type'    => 'String',
				'resolve' => function( $post, $args, $context, $info ) {
					$variables = get_post_meta( $post->ID, 'variables', true );

					return ! empty( $variables ) ? $variables : null;
				}
			],
			'graphQLOperation'    => [
				'type'    => 'String',
				'resolve' => function( $post ) {
					$operation = get_post_meta( $post->ID, 'operation', true );

					return ! empty( $operation ) ? $operation : null;
				}
			],
			'headers'             => [
				'type'    => [ 'list_of' => 'String' ],
				'resolve' => function( $post ) {
					$headers = get_post_meta( $post->ID, 'headers', true );
					$headers = (array) json_decode( $headers );
					$return  = [];
					if ( ! empty( $headers ) && is_array( $headers ) ) {
						foreach ( $headers as $key => $value ) {
							$return[ $key ] = $key . ' ___ ' . $value;
						}
					}

					return ! empty( $return ) ? $return : null;
				}
			],
			'createdDate'         => [
				'type'    => 'String',
				'resolve' => function( $post, $args, $context, $info ) {
					$created_date = get_post_meta( $post->ID, 'created_date', true );
					$created_date = json_decode( $created_date );

					return ! empty( $created_date ) ? $created_date : null;
				}
			],
			'doingAutosave'       => [
				'type'    => 'Boolean',
				'resolve' => function( $post, $args, $context, $info ) {
					$doing_autosave = get_post_meta( $post->ID, 'doing_autosave', true );
					$doing_autosave = json_decode( $doing_autosave );

					return true === $doing_autosave ? $doing_autosave : false;
				}
			],
			'isUpdate'            => [
				'type'    => 'Boolean',
				'resolve' => function( $post, $args, $context, $info ) {
					$is_update = get_post_meta( $post->ID, 'is_update', true );
					$is_update = json_decode( $is_update );

					return true === $is_update ? $is_update : false;
				}
			],
			'updatedDate'         => [
				'type'    => 'String',
				'resolve' => function( $post, $args, $context, $info ) {
					$udpate_date = get_post_meta( $post->ID, 'update_date', true );
					$udpate_date = json_decode( $udpate_date );

					return ! empty( $udpate_date ) ? $udpate_date : null;
				}
			]
		] );
		
	} );

	/**
	 * Register the connection between Posts and the Mutation Logs
	 */
	add_action( 'graphql_register_types', function() {
		
		register_graphql_connection( [
			'fromType'      => 'Post',
			'toType'        => 'MutationLog',
			'fromFieldName' => 'mutationLogs',
			'resolveNode'   => function( $id, $args, $context, $info ) {
				return DataSource::resolve_post_object( $id, $context );
			},
			'resolve'       => function( Post $post, $args, $context, $info ) {
				$resolver = new PostObjectConnectionResolver( $post, $args, $context, $info, 'graphql_mutation_log' );
				$resolver->setQueryArg( 'post_parent', $post->ID );
				$resolver->setQueryArg( 'post_type', 'graphql_mutation_log' );
				$resolver->setQueryArg( 'post_status', 'any' );

				return $resolver->get_connection();
			}
		] );

	} );