Example for a GraphQL Application in Spring Boot (#2477)

spring-boot/pom.xml

@@ -40,6 +40,22 @@
             <artifactId>spring-boot-starter-security</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-spring-boot-starter</artifactId>
+            <version>3.6.0</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphiql-spring-boot-starter</artifactId>
+            <version>3.6.0</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java-tools</artifactId>
+            <version>3.2.0</version>
+        </dependency>
+
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-tomcat</artifactId>

spring-boot/src/main/java/com/baeldung/graphql/Author.java

@@ -0,0 +1,31 @@
+package com.baeldung.graphql;
+
+public class Author {
+    private String id;
+    private String name;
+    private String thumbnail;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getThumbnail() {
+        return thumbnail;
+    }
+
+    public void setThumbnail(String thumbnail) {
+        this.thumbnail = thumbnail;
+    }
+}

spring-boot/src/main/java/com/baeldung/graphql/AuthorDao.java

@@ -0,0 +1,18 @@
+package com.baeldung.graphql;
+
+import java.util.List;
+import java.util.Optional;
+
+public class AuthorDao {
+    private List<Author> authors;
+
+    public AuthorDao(List<Author> authors) {
+        this.authors = authors;
+    }
+
+    public Optional<Author> getAuthor(String id) {
+        return authors.stream()
+            .filter(author -> id.equals(author.getId()))
+            .findFirst();
+    }
+}

spring-boot/src/main/java/com/baeldung/graphql/AuthorResolver.java

@@ -0,0 +1,17 @@
+package com.baeldung.graphql;
+
+import java.util.List;
+
+import com.coxautodev.graphql.tools.GraphQLResolver;
+
+public class AuthorResolver implements GraphQLResolver<Author> {
+    private PostDao postDao;
+
+    public AuthorResolver(PostDao postDao) {
+        this.postDao = postDao;
+    }
+
+    public List<Post> getPosts(Author author) {
+        return postDao.getAuthorPosts(author.getId());
+    }
+}

spring-boot/src/main/java/com/baeldung/graphql/GraphqlConfiguration.java

@@ -0,0 +1,59 @@
+package com.baeldung.graphql;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class GraphqlConfiguration {
+    @Bean
+    public PostDao postDao() {
+        List<Post> posts = new ArrayList<>();
+        for (int postId = 0; postId < 10; ++postId) {
+            for (int authorId = 0; authorId < 10; ++authorId) {
+                Post post = new Post();
+                post.setId("Post" + authorId + postId);
+                post.setTitle("Post " + authorId + ":" + postId);
+                post.setText("Post " + postId + " + by author " + authorId);
+                post.setAuthorId("Author" + authorId);
+                posts.add(post);
+            }
+        }
+        return new PostDao(posts);
+    }
+
+    @Bean
+    public AuthorDao authorDao() {
+        List<Author> authors = new ArrayList<>();
+        for (int authorId = 0; authorId < 10; ++authorId) {
+            Author author = new Author();
+            author.setId("Author" + authorId);
+            author.setName("Author " + authorId);
+            author.setThumbnail("http://example.com/authors/" + authorId);
+            authors.add(author);
+        }
+        return new AuthorDao(authors);
+    }
+
+    @Bean
+    public PostResolver postResolver(AuthorDao authorDao) {
+        return new PostResolver(authorDao);
+    }
+
+    @Bean
+    public AuthorResolver authorResolver(PostDao postDao) {
+        return new AuthorResolver(postDao);
+    }
+
+    @Bean
+    public Query query(PostDao postDao) {
+        return new Query(postDao);
+    }
+
+    @Bean
+    public Mutation mutation(PostDao postDao) {
+        return new Mutation(postDao);
+    }
+}

spring-boot/src/main/java/com/baeldung/graphql/Mutation.java

@@ -0,0 +1,25 @@
+package com.baeldung.graphql;
+
+import java.util.UUID;
+
+import com.coxautodev.graphql.tools.GraphQLMutationResolver;
+
+public class Mutation implements GraphQLMutationResolver {
+    private PostDao postDao;
+
+    public Mutation(PostDao postDao) {
+        this.postDao = postDao;
+    }
+
+    public Post writePost(String title, String text, String category, String author) {
+        Post post = new Post();
+        post.setId(UUID.randomUUID().toString());
+        post.setTitle(title);
+        post.setText(text);
+        post.setCategory(category);
+        post.setAuthorId(author);
+        postDao.savePost(post);
+
+        return post;
+    }
+}

spring-boot/src/main/java/com/baeldung/graphql/Post.java

@@ -0,0 +1,49 @@
+package com.baeldung.graphql;
+
+public class Post {
+    private String id;
+    private String title;
+    private String text;
+    private String category;
+    private String authorId;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public String getCategory() {
+        return category;
+    }
+
+    public void setCategory(String category) {
+        this.category = category;
+    }
+
+    public String getAuthorId() {
+        return authorId;
+    }
+
+    public void setAuthorId(String authorId) {
+        this.authorId = authorId;
+    }
+}

spring-boot/src/main/java/com/baeldung/graphql/PostDao.java

@@ -0,0 +1,29 @@
+package com.baeldung.graphql;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class PostDao {
+    private List<Post> posts;
+
+    public PostDao(List<Post> posts) {
+        this.posts = posts;
+    }
+
+    public List<Post> getRecentPosts(int count, int offset) {
+        return posts.stream()
+            .skip(offset)
+            .limit(count)
+            .collect(Collectors.toList());
+    }
+
+    public List<Post> getAuthorPosts(String author) {
+        return posts.stream()
+            .filter(post -> author.equals(post.getAuthorId()))
+            .collect(Collectors.toList());
+    }
+
+    public void savePost(Post post) {
+        posts.add(0, post);
+    }
+}

spring-boot/src/main/java/com/baeldung/graphql/PostResolver.java

@@ -0,0 +1,17 @@
+package com.baeldung.graphql;
+
+import java.util.Optional;
+
+import com.coxautodev.graphql.tools.GraphQLResolver;
+
+public class PostResolver implements GraphQLResolver<Post> {
+    private AuthorDao authorDao;
+
+    public PostResolver(AuthorDao authorDao) {
+        this.authorDao = authorDao;
+    }
+
+    public Optional<Author> getAuthor(Post post) {
+        return authorDao.getAuthor(post.getAuthorId());
+    }
+}

spring-boot/src/main/java/com/baeldung/graphql/Query.java

@@ -0,0 +1,17 @@
+package com.baeldung.graphql;
+
+import java.util.List;
+
+import com.coxautodev.graphql.tools.GraphQLQueryResolver;
+
+public class Query implements GraphQLQueryResolver {
+    private PostDao postDao;
+
+    public Query(PostDao postDao) {
+        this.postDao = postDao;
+    }
+
+    public List<Post> recentPosts(int count, int offset) {
+        return postDao.getRecentPosts(count, offset);
+    }
+}

spring-boot/src/main/java/org/baeldung/boot/DemoApplication.java

@@ -1,11 +1,14 @@
 package org.baeldung.boot;
 
+import com.baeldung.graphql.GraphqlConfiguration;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 
 import com.baeldung.autoconfiguration.MySQLAutoconfiguration;
+import org.springframework.context.annotation.Import;
 
 @SpringBootApplication(exclude=MySQLAutoconfiguration.class)
+@Import(GraphqlConfiguration.class)
 public class DemoApplication {
 
     public static void main(String[] args) {

spring-boot/src/main/resources/graphql/blog.graphqls

@@ -0,0 +1,24 @@
+type Post {
+    id: ID!
+    title: String!
+    text: String!
+    category: String
+    author: Author
+}
+
+type Author {
+    id: ID!
+    name: String!
+    thumbnail: String
+    posts: [Post]!
+}
+
+# The Root Query for the application
+type Query {
+    recentPosts(count: Int, offset: Int): [Post]!
+}
+
+# The Root Mutation for the application
+type Mutation {
+    writePost(title: String!, text: String!, category: String, author: String!) : Post!
+}