Extend GraphQL API

Introduction

When it comes to HTTP API development, Webiny relies on GraphQL. In fact, all of the applications that are part of the Webiny Serverless CMS, for example Page Builder or Headless CMS, are using it to enable developers programmatic interaction via a client of their choice, for example, a browser.

Extending GraphQL API

In general, when talking about extending an existing GraphQL API, we’re usually referring to one or more of the following:

• adding new query or mutation GraphQL operations
• adding new GraphQL types
• extending existing GraphQL types with additional fields

For example, we might want to add a new, Page Builder-related, duplicatePage mutation, that would be responsible for making copies of provided pages. Or, we might just want to add an extra field to the PbPage GraphQL type, so that we can store some additional data for each page.

Depending on the application and the change we want to perform, some of the steps in the overall GraphQL extension process may differ, in all cases, we will want to start by registering a new [GraphQLSchemaPlugin] plugin.

The plugin is registered within your GraphQL API’s application code [apps/api/graphql/src/plugins] folder, and register it in the [apps/api/graphql/src/index.ts] entrypoint file.

The following is an example of a simple CmsGraphQLSchemaPlugin plugin that extends the default GraphQL API with a new listBooks query.

Once your plugin is ready, add it to the entrypoint like so:

Declaring your API using GraphQLSchemaPlugin means your API will be registered under the default API, so your new query (listBooks) will be visible in the API playground under the Main API tab.

Executing the query should give us the following result:

Executing the new listBooks Query via API Playground

(click to enlarge)

In case you wish to extend the Headless CMS API, you would just replace GraphQLSchemaPlugin with CMSGraphQLSchemaPlugin in your plugin, and everything else remains the same. Doing this your plugin will be visible under the “Headless CMS - Manage API” tab in the API Playground and you need to use the matching GraphQL URL.

Additional Related Examples

For more concrete examples, you can also visit the following guides which explain how to extend GraphQL types and operations that belong to different Webiny applications:

• Page Builder
• Headless CMS