Add REST api in front of DGS in same spring boot project

[aisensiy]

I found that graphql is really convenient to generate complex query result. For example a schema like this:

type Query {
  article(id: String!): Article
}

type User {
  username: String!
  email: String!
}

type Article {
  id: String!
  title: String!
  author: User!
  content: String!
  createdAt: DateTime!
  author: User!
  comments: [Comment!]!
}

type Comment {
  id: String!
  article: Article!
  author: User!
  content: String!
  createdAt: DateTime!
}

If I want query an article including its author, the query can be like this:

query {
  article(id: "aabb") {
    id
    title
    content
    author {
      username
      email
    }
  }
}

My question is that it is possible to create a RESTful API and use the dgs as query service in the same spring boot project like below:

@RestController
public class ArticleApi {
  private DgsService dgsService;

  @GetMapping("/articles/{articleId}")
  public ArticleResponse getArticleById(@PathParameter("articleId") String articleId) {
    return ArticleResponse.build(dgsService.query("<the graphql query>");
  } 
}

[oonxt]

try this:
https://netflix.github.io/dgs/advanced/java-client/

[srinivasankavitha]

You'll need to do something similar to how we handle this in the DGS framework: https://github.com/Netflix/dgs-framework/blob/master/graphql-dgs-spring-webmvc/src/main/kotlin/com/netflix/graphql/dgs/mvc/DgsRestController.kt#L100

[owengalenjones]

Thanks, I think I got it!

[srikanthrks]

@owengalenjones were you able to execute the graphql query in your REST method implementation. Looking for a similar way to call the method annotated with @DgsQuery (getArticle) from within @GetMapping("/articles/{articleId}") public ArticleResponse getArticleById()

public class ArticleDataFetcher {
  @DgsQuery
  public Article getArticle(@InputArgument String id) {
    if(id.isEmpty()){
      throw new IllegalArgumentException("id is required");
    }
    return new Article();
  }

[owengalenjones]

@srikanthrks: If you need it in a RestMVC @GetMapping I have not personally tested it, but the DGS / graphql-java executor is accessible and you can probably call it from wherever:

public class GetMappingDGSAdapter {

  private final DgsQueryExecutor executor;

  @GetMapping("/articles/{articleId}")
  public ArticleResponse getArticleById() {

    var body = new GraphQLRequestBody(...)

      return executor.execute(
          body.getQuery(),
          body.getVariables(),
          Map.of(),
          null,
          body.getOperationName(),
          null
      );
  }

  ...

  public static class GraphQLRequestBody {

    private String query;
    private String operationName;
    private Map<String, Object> variables = new LinkedHashMap<>();
  }

Once the executor is invoked it should find the @DgsQuery annotated method and invoke it.

[srikanthrks]

@owengalenjones Thanks for the suggestion. Will try this out