You'll need the `spring-boot-starter-graphql` starter at a minimum.
Because GraphQL is transport-agnostic, you'll also need to have one or more additional starters in your application to expose your GraphQL API over the web:
A Spring GraphQL application requires a defined schema at startup.
By default, you can write ".graphqls" or ".gqls" schema files under `src/main/resources/graphql/**` and Spring Boot will pick them up automatically.
You can customize the locations with configprop:spring.graphql.schema.locations[] and the file extensions with configprop:spring.graphql.schema.file-extensions[].
NOTE: By default, https://spec.graphql.org/draft/#sec-Introspection[field introspection] will be allowed on the schema as it is required for tools such as GraphiQL.
If you wish to not expose information about the schema, you can disable introspection by setting configprop:spring.graphql.schema.introspection.enabled[] to `false`.
You can declare `RuntimeWiringConfigurer` beans in your Spring config to get access to the `RuntimeWiring.Builder`.
Spring Boot detects such beans and adds them to the {spring-graphql-docs}#execution-graphqlsource[GraphQlSource builder].
Typically, however, applications will not implement `DataFetcher` directly and will instead create {spring-graphql-docs}#controllers[annotated controllers].
The GraphQL WebSocket endpoint is off by default. To enable it:
* For a Servlet application, add the WebSocket starter `spring-boot-starter-websocket`
* For a WebFlux application, no additional dependency is required
* For both, the configprop:spring.graphql.websocket.path[] application property must be set
Spring GraphQL provides a {spring-graphql-docs}#web-interception[Web Interception] model.
This is quite useful for retrieving information from an HTTP request header and set it in the GraphQL context or fetching information from the same context and writing it to a response header.
With Spring Boot, you can declare a `WebInterceptor` bean to have it registered with the web transport.
{spring-framework-docs}/web.html#mvc-cors[Spring MVC] and {spring-framework-docs}/web-reactive.html#webflux-cors[Spring WebFlux] support CORS (Cross-Origin Resource Sharing) requests.
CORS is a critical part of the web config for GraphQL applications that are accessed from browsers using different domains.
Spring Boot supports many configuration properties under the `spring.graphql.cors.*` namespace; here's a short configuration sample:
RSocket is also supported as a transport, on top of WebSocket or TCP.
Once the <<messaging#messaging.rsocket.server-auto-configuration,RSocket server is configured>>, we can configure our GraphQL handler on a particular route using configprop:spring.graphql.rsocket.mapping[].
Spring GraphQL enables applications to register one or more Spring `DataFetcherExceptionResolver` components that are invoked sequentially.
The Exception must be resolved to a list of `graphql.GraphQLError` objects, see {spring-graphql-docs}#execution-exceptions[Spring GraphQL exception handling documentation].
Spring Boot will automatically detect `DataFetcherExceptionResolver` beans and register them with the `GraphQlSource.Builder`.
[[web.graphql.graphiql]]
=== GraphiQL and Schema printer
Spring GraphQL offers infrastructure for helping developers when consuming or developing a GraphQL API.
This page is disabled by default and can be turned on with the configprop:spring.graphql.graphiql.enabled[] property.
Many applications exposing such a page will prefer a custom build.
A default implementation is very useful during development, this is why it is exposed automatically with <<using#using.devtools,`spring-boot-devtools`>> during development.
You can also choose to expose the GraphQL schema in text format at `/graphql/schema` when the configprop:spring.graphql.schema.printer.enabled[] property is enabled.
