With the rise in popularity of GraphQL as an alternative to traditional REST APIs, it becomes necessary to find ways to document GraphQL APIs effectively. One way to achieve this is by leveraging Java Spring REST Docs, a powerful tool for generating documentation for REST APIs. In this blog post, we will explore how to integrate Java Spring REST Docs with GraphQL to create comprehensive and informative API documentation.

Why use Java Spring REST Docs?

Java Spring REST Docs is an excellent choice for documenting APIs due to its ability to automatically generate documentation from tests. It provides a simple yet powerful way to describe the API endpoints, their request/response formats, and any additional information required for documentation.

Setting up Java Spring REST Docs

To begin, let’s set up Java Spring REST Docs in our Spring Boot application. Start by adding the necessary dependencies to your pom.xml or build.gradle file:

<dependency>
    <groupId>org.springframework.restdocs</groupId>
    <artifactId>spring-restdocs-mockmvc</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.springframework.restdocs</groupId>
    <artifactId>spring-restdocs-asciidoctor</artifactId>
    <version>${spring-restdocs.version}</version>
    <scope>test</scope>
</dependency>

Next, configure Spring MVC to use REST Docs by adding the following line to your test class:

@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureRestDocs(outputDir = "target/generated-snippets")
public class YourTests {
    // ...
}

Generating GraphQL documentation with Java Spring REST Docs

Now that we have Java Spring REST Docs set up, let’s explore how to generate documentation for our GraphQL API.

1. Start by creating a Spring MVC test for your GraphQL endpoint. Mock the server’s response using a GraphQL query, and perform a request using Spring’s MockMvc:

@Test
public void testGraphQLQuery() throws Exception {
    String query = "query { ... }"; // Your GraphQL query here
    
    mockMvc.perform(post("/graphql")
            .contentType(MediaType.APPLICATION_JSON)
            .content(query))
            .andExpect(status().isOk())
            .andDo(document("{class-name}/{method-name}",
                requestFields(
                    fieldWithPath("query").description("GraphQL query to execute")
                ),
                responseFields(
                    // Define your expected response fields
                )
            ));
}

1. Run the test, and Java Spring REST Docs will automatically generate documentation snippets in AsciiDoc format under the target/generated-snippets directory.

2. Finally, you can create a composite AsciiDoc file that references these snippets and generates the final documentation:

= API Documentation

== GraphQL API

=== Query

[source,http,options="nowrap"]
----
POST /graphql
Content-Type: application/json

{ "query": "query { ... }" }
----

include::{snippets}/your-package-name/your-graphql-test-method-name/curl-request.adoc[]
include::{snippets}/your-package-name/your-graphql-test-method-name/http-response.adoc[]

By following these steps, you can easily generate comprehensive API documentation for your GraphQL endpoints using Java Spring REST Docs.

Conclusion

Integrating Java Spring REST Docs with GraphQL provides a powerful approach to documenting GraphQL APIs. By leveraging the simplicity and automation of Java Spring REST Docs, developers can create clear and informative API documentation that enhances the usability and adoption of their GraphQL APIs.

#TechBlog #API #Documentation