LEIAME.md

Spring - GraphQL - Articles

Projeto Java com Spring e Gradle para criar uma aplicação GraphQL de Articles.

Passos

Os passos da implementação do projeto:

1. Criar projeto (no IntelliJ) com:

• Linguagem Java (17);
• Spring Framework (6.2.3);
• Dependências: Web, GraphQL, DevTools e Lombok.

2. Em src/main/resources/graphql, criar schema.graphqls ou schema.gqls:

• A consulta é buscar artigo pelo seu id;
• Cada artigo possui id, name, author;
• Cada author pode possuir id, fullname, username.

type Query {
  articleById(id: ID): Article
}

type Article {
    id: ID
    name: String
    author: Author
}

type Author {
    id: ID
    fullname: String
    username: String
}

3. Criar record Author:

• com campos id, fullname, username do tipo String;
• com campo static authorList;
• com método static Author getById(String id).

package com.project.javaspringgraphqlarticles.data;
public record Author(String id, String fullname, String username) {

    private static List<Author> authorList = Arrays.asList(
            new Author("author-1", "Arthur Ignatius Conan Doyle", "aicd"),
            new Author("author-2", "Researcher Holmes", "rshlm"),
            new Author("author-3", "Dr. Watson", "drwt")
    );
  
    public static Author getById(String id){
      return Author.authorList
              .stream()
              .filter(author -> author.id().equals(id))
              .findFirst().orElse(null);
    }
}

4. Criar record Article:

• com campos id, name, authorId do tipo String;
• com campo static articleList;
• com método static Article getById(String id).

package com.project.javaspringgraphqlarticles.data;
public record Article(String id, String name, String authorId) {

    private static List<Article> articleList = Arrays.asList(
            new Article("article-1", "A study in scarlet red", "author-1"),
            new Article("article-2", "A Sherlock Adventure", "author-2"),
            new Article("article-3", " The Memoirs of Holmes", "author-3")
    );
  
    public static Article getById(String id){
      return Article.articleList
              .stream()
              .filter(article -> article.id().equals(id))
              .findFirst()
              .orElse(null);
    }
}

5. Criar classe ArticleController:

• no pacote controllers;
• anotada com @Controller;
• com os métodos:
  • @QueryMapping public Article articleById(@Argument String id);
  • @SchemaMapping public Author author(Article article).

package com.project.javaspringgraphqlarticles.controllers;
@Controller
public class ArticleController {

    @QueryMapping
    public Article articleById(@Argument String id){
        return Article.getById(id);
    }

    @SchemaMapping
    public Author author(Article article){
        return Author.getById(article.authorId());
    }
}

6. Configurar application.properties para:

• definir rota da api graphql como /api/graphql;
• ativar graphiql;
• definir rota da api graphiql como api/tests/graphiql.

spring.application.name=Java-Spring-GraphQL-Articles
spring.graphql.path=/api/graphql
spring.graphql.graphiql.enabled=true
spring.graphql.graphiql.path=api/tests/graphiql

7. Para testar, acesse http://localhost:8080/api/tests/graphiql?path=/api/graphql com o navegador (ou use o POSTMAN):

Obs.:

• Os nomes em Query schema.graphqls devem ser os mesmos dos métodos das Controllers anotados com @QueryMapping.

Referências

Baeldung - Getting Started with GraphQL and Spring Boot: https://www.baeldung.com/spring-graphql

Baeldung - Introduction to GraphQL: https://www.baeldung.com/graphql

Spring - Guides - Building a GraphQL service: https://spring.io/guides/gs/graphql-server

GraphQL Java - Tutorial - Getting started with Spring for GraphQL: https://www.graphql-java.com/tutorials/getting-started-with-spring-boot/