Return Map from GraphQL (#11966)

* Return Map from GraphQL

Three techniques have been used

1. Return as Json String
2. Return Json using GraphQL scalar type
3. Return as list of key-value pair

* Adding custom scalar in plugin configuration

* Build failure fix
1. Integrating the .graphqls files
2. Updating the respective query resolvers

* Build failure Fix

1. Removed the extra .graphql file

2. Added ExtendedGraphQLScalarType class because the parent class didn't 
have default constructor and the client code generation plugin was 
requiring it.

* Code refactoring

* Code refactoring

graphql/graphql-java/pom.xml

@@ -36,6 +36,21 @@
             <artifactId>graphql-java-annotations</artifactId>
             <version>${graphql-java-annotations.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.ratpack</groupId>
+            <artifactId>ratpack-core</artifactId>
+            <version>${ratpack-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.github.americanexpress.nodes</groupId>
+            <artifactId>nodes</artifactId>
+            <version>0.5.0</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java</artifactId>
+            <version>11.0</version>
+        </dependency>
         <dependency>
             <groupId>com.graphql-java</groupId>
             <artifactId>graphql-java-tools</artifactId>
@@ -95,6 +110,14 @@
             <version>${mockserver-client-java.version}</version>
             <scope>test</scope>
         </dependency>
+
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java-extended-scalars</artifactId>
+            <version>${graphql-java-extended-scalars.version}</version>
+        </dependency>
+
+
     </dependencies>
 
     <build>
@@ -133,6 +156,13 @@
                     <copyRuntimeSources>false</copyRuntimeSources>
                     <generateDeprecatedRequestResponse>false</generateDeprecatedRequestResponse>
                     <separateUtilityClasses>true</separateUtilityClasses>
+                    <customScalars>
+                        <customScalar>
+                            <graphQLTypeName>JSON</graphQLTypeName>
+                            <javaType>java.util.Map</javaType>
+                            <graphQLScalarTypeClass>com.baeldung.graphqlreturnmap.ExtendedGraphQLScalarType</graphQLScalarTypeClass>
+                        </customScalar>
+                    </customScalars>
                 </configuration>
             </plugin>
         </plugins>
@@ -154,6 +184,8 @@
 
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
+        <graphql.java.generator.version>1.18</graphql.java.generator.version>
+        <graphql-java-extended-scalars.version>2022-04-06T00-10-27-a70541e</graphql-java-extended-scalars.version>
     </properties>
 
 </project>

graphql/graphql-java/src/main/java/com/baeldung/graphql/server/GraphQLQuery.java

@@ -2,6 +2,7 @@ package com.baeldung.graphql.server;
 
 import com.baeldung.graphql.data.Book;
 import com.baeldung.graphql.data.BookRepository;
+import com.baeldung.graphqlreturnmap.entity.Product;
 import com.coxautodev.graphql.tools.GraphQLQueryResolver;
 
 import java.util.List;
@@ -18,4 +19,12 @@ public class GraphQLQuery implements GraphQLQueryResolver {
         return repository.getAllBooks();
     }
 
+    public List<Product> getProducts(int pageSize, int pageNumber) {
+        return null;
+    }
+
+    public Product getProduct(int id) {
+        return null;
+    }
+
 }

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/AppHandler.java

@@ -0,0 +1,52 @@
+package com.baeldung.graphqlreturnmap;
+
+import com.baeldung.graphql.utils.SchemaUtils;
+import com.baeldung.graphqlreturnmap.resolver.ProductResolver;
+import com.baeldung.graphqlreturnmap.resolver.Query;
+import com.coxautodev.graphql.tools.SchemaParser;
+import graphql.ExecutionResult;
+import graphql.GraphQL;
+import graphql.scalars.ExtendedScalars;
+import graphql.schema.GraphQLSchema;
+import ratpack.handling.Context;
+import ratpack.handling.Handler;
+
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.logging.Logger;
+
+import static ratpack.jackson.Jackson.json;
+
+public class AppHandler implements Handler {
+    private static final Logger LOGGER = Logger.getLogger(AppHandler.class.getSimpleName());
+    private GraphQL graphql;
+
+    public AppHandler() throws Exception {
+        GraphQLSchema schema = SchemaParser.newParser()
+            .resolvers(new Query(), new ProductResolver())
+            .scalars(ExtendedScalars.Json)
+            .file("schema.graphqls")
+            .build()
+            .makeExecutableSchema();
+        graphql = GraphQL.newGraphQL(schema).build();
+    }
+
+    @Override
+    public void handle(Context context) throws Exception {
+        context.parse(Map.class)
+            .then(payload -> {
+                ExecutionResult executionResult = graphql.execute(payload.get(SchemaUtils.QUERY)
+                    .toString(), null, this, Collections.emptyMap());
+                Map<String, Object> result = new LinkedHashMap<>();
+                if (executionResult.getErrors()
+                    .isEmpty()) {
+                    result.put(SchemaUtils.DATA, executionResult.getData());
+                } else {
+                    result.put(SchemaUtils.ERRORS, executionResult.getErrors());
+                    LOGGER.warning("Errors: " + executionResult.getErrors());
+                }
+                context.render(json(result));
+            });
+    }
+}

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/ExtendedGraphQLScalarType.java

@@ -0,0 +1,24 @@
+package com.baeldung.graphqlreturnmap;
+
+import graphql.language.ScalarTypeDefinition;
+import graphql.schema.Coercing;
+import graphql.schema.GraphQLDirective;
+import graphql.schema.GraphQLScalarType;
+
+import java.util.List;
+
+public class ExtendedGraphQLScalarType extends GraphQLScalarType {
+
+    public ExtendedGraphQLScalarType(){
+        super("","",null);
+
+    }
+
+    public ExtendedGraphQLScalarType(String name, String description, Coercing coercing) {
+        super(name, description, coercing);
+    }
+
+    public ExtendedGraphQLScalarType(String name, String description, Coercing coercing, List<GraphQLDirective> directives, ScalarTypeDefinition definition) {
+        super(name, description, coercing, directives, definition);
+    }
+}

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/GraphqlReturnMap.java

@@ -0,0 +1,12 @@
+package com.baeldung.graphqlreturnmap;
+
+import ratpack.server.RatpackServer;
+
+public class GraphqlReturnMap {
+
+    public static void main(String[] args) throws Exception {
+        final RatpackServer server = RatpackServer.of(s -> s.handlers(chain -> chain.post("product", new AppHandler())));
+        server.start();
+    }
+
+}

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/entity/Attribute.java

@@ -0,0 +1,46 @@
+package com.baeldung.graphqlreturnmap.entity;
+
+public class Attribute {
+    private String name;
+    private String description;
+    private String unit;
+
+    public Attribute(String name, String description, String unit){
+        this.name = name;
+        this.description = description;
+        this.unit = unit;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public String getUnit() {
+        return unit;
+    }
+
+    public void setUnit(String unit) {
+        this.unit = unit;
+    }
+
+    @Override
+    public String toString() {
+        return "Attribute{" +
+                "name='" + name + '\'' +
+                ", description='" + description + '\'' +
+                ", unit='" + unit + '\'' +
+                '}';
+    }
+}

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/entity/Product.java

@@ -0,0 +1,48 @@
+package com.baeldung.graphqlreturnmap.entity;
+
+
+import java.util.Map;
+
+public class Product {
+    private Integer id;
+    private String name;
+    private String description;
+    private Map<String, Attribute> attributes;
+
+
+    public Product(){
+
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public Map<String, Attribute> getAttributes() {
+        return attributes;
+    }
+
+    public void setAttributes(Map<String, Attribute> attributes) {
+        this.attributes = attributes;
+    }
+}

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/model/AttributeKeyValueModel.java

@@ -0,0 +1,30 @@
+package com.baeldung.graphqlreturnmap.model;
+
+
+import com.baeldung.graphqlreturnmap.entity.Attribute;
+
+public class AttributeKeyValueModel {
+    private String key;
+    private Attribute value;
+
+    public AttributeKeyValueModel(String key, Attribute value) {
+        this.key = key;
+        this.value = value;
+    }
+
+    public String getKey() {
+        return key;
+    }
+
+    public void setKey(String key) {
+        this.key = key;
+    }
+
+    public Attribute getValue() {
+        return value;
+    }
+
+    public void setValue(Attribute value) {
+        this.value = value;
+    }
+}

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/repository/ProductRepository.java

@@ -0,0 +1,12 @@
+package com.baeldung.graphqlreturnmap.repository;
+
+
+import com.baeldung.graphqlreturnmap.entity.Product;
+
+import java.util.List;
+
+public interface ProductRepository {
+    List<Product> getProducts(Integer pageSize, Integer pageNumber);
+    Product getProduct(Integer id);
+
+}

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/repository/impl/ProductRepositoryImpl.java

@@ -0,0 +1,43 @@
+package com.baeldung.graphqlreturnmap.repository.impl;
+
+import com.baeldung.graphqlreturnmap.entity.Attribute;
+import com.baeldung.graphqlreturnmap.entity.Product;
+import com.baeldung.graphqlreturnmap.repository.ProductRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+@Repository
+public class ProductRepositoryImpl implements ProductRepository {
+
+    private static List<Product> productList = new ArrayList<>();
+
+    public ProductRepositoryImpl() {
+        for (int i = 1; i <= 10; i++){
+            Product product = new Product();
+            product.setId(i);
+            product.setName(String.format("Product %d", i));
+            product.setDescription(String.format("Product %d description", i));
+            product.setAttributes(createAttributes(i));
+            productList.add(product);
+        }
+    }
+
+    private Map<String, Attribute> createAttributes(int i) {
+        Map<String, Attribute> attributeMap = new HashMap<>();
+        attributeMap.put(String.format("attribute_%d",i), new Attribute(String.format("Attribute%d name",i),"This is custom attribute description","This is custom attribute unit"));
+        attributeMap.put("size", new Attribute((i & 1) == 0 ? "Small" : "Large","This is custom attribute description","This is custom attribute unit"));
+        return attributeMap;
+    }
+
+    @Override
+    public List<Product> getProducts(Integer pageSize, Integer pageNumber) {
+        return productList.stream().skip(pageSize*pageNumber).limit(pageSize).collect(Collectors.toList());
+    }
+
+    @Override
+    public Product getProduct(Integer id) {
+        return productList.stream().filter(product -> product.getId().equals(id)).findFirst().orElse(null);
+    }
+}

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/resolver/ProductResolver.java

@@ -0,0 +1,30 @@
+package com.baeldung.graphqlreturnmap.resolver;
+
+import com.baeldung.graphqlreturnmap.entity.Product;
+import com.baeldung.graphqlreturnmap.model.AttributeKeyValueModel;
+import com.coxautodev.graphql.tools.GraphQLResolver;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import java.util.LinkedList;
+import java.util.List;
+
+public class ProductResolver implements GraphQLResolver<Product> {
+    public ProductResolver(){
+    }
+
+    public List<AttributeKeyValueModel> getAttribute_list(Product product){
+        List<AttributeKeyValueModel> attributeModelList = new LinkedList<>();
+        product.getAttributes().forEach((key, val) -> attributeModelList.add(new AttributeKeyValueModel(key, val)));
+        return attributeModelList;
+    }
+
+    public String getAttribute_string(Product product){
+        try {
+            return new ObjectMapper().writeValueAsString(product.getAttributes());
+        } catch (JsonProcessingException e) {
+            e.printStackTrace();
+            return "";
+        }
+    }
+}

graphql/graphql-java/src/main/java/com/baeldung/graphqlreturnmap/resolver/Query.java

@@ -0,0 +1,33 @@
+package com.baeldung.graphqlreturnmap.resolver;
+
+import com.baeldung.graphql.data.Book;
+import com.baeldung.graphqlreturnmap.entity.Product;
+import com.baeldung.graphqlreturnmap.repository.ProductRepository;
+import com.baeldung.graphqlreturnmap.repository.impl.ProductRepositoryImpl;
+import com.coxautodev.graphql.tools.GraphQLQueryResolver;
+import org.springframework.beans.factory.annotation.Autowired;
+
+import java.util.List;
+
+public class Query implements GraphQLQueryResolver {
+
+    @Autowired
+    private ProductRepository productRepository;
+    public Query(){
+        productRepository = new ProductRepositoryImpl();
+    }
+
+    public List<Product> getProducts(int pageSize, int pageNumber) {
+        return productRepository.getProducts(pageSize, pageNumber);
+    }
+
+    public Product getProduct(int id) {
+        return productRepository.getProduct(id);
+    }
+
+    public List<Book> allBooks() {
+        return null;
+    }
+
+
+}

graphql/graphql-java/src/main/resources/schema.graphqls

@@ -10,8 +10,34 @@ type Author {
 
 type Query {
   allBooks: [Book]
+  products(size: Int, page: Int): [Product]!
+  product(id: Int): Product!
 }
 
+
+
+type Product {
+  id: ID
+  name: String!
+  description: String
+  attribute_string:String
+  attribute_list:[AttributeKeyValuePair]
+  attributes: JSON
+}
+
+type AttributeKeyValuePair {
+  key:String
+  value:Attribute
+}
+
+type Attribute {
+  name:String
+  description:String
+  unit:String
+}
+scalar JSON
+
+
 schema {
   query: Query
 }