Add new example for spring-boot-dgs.

This example shows, how a type can be extended with a custom data fetcher. It utilises Netflix Domain Graph Service (DGS).

examples/dgs-spring-boot/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.neo4j</groupId>
+        <artifactId>neo4j-graphql-java-examples</artifactId>
+        <version>1.3.1-SNAPSHOT</version>
+    </parent>
+
+    <groupId>org.neo4j.graphql.examples</groupId>
+    <artifactId>dgs-spring-boot</artifactId>
+
+    <name>Example - dgs-spring-boot</name>
+    <description>Example for using neo4j-graphql-java with Spring Boot and Netflix Domain Graph Service (DGS)</description>
+
+    <properties>
+        <testcontainers.version>1.15.3</testcontainers.version>
+        <spring-boot.version>2.3.10.RELEASE</spring-boot.version>
+    </properties>
+
+    <dependencies>
+        <!-- spring dependencies -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-configuration-processor</artifactId>
+            <optional>true</optional>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+
+        <!-- neo4j driver + the neo4j-graphql-java library -->
+        <dependency>
+            <groupId>org.neo4j.driver</groupId>
+            <artifactId>neo4j-java-driver-spring-boot-starter</artifactId>
+            <version>4.2.4.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.neo4j</groupId>
+            <artifactId>neo4j-graphql-java</artifactId>
+            <version>1.3.1-SNAPSHOT</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.netflix.graphql.dgs</groupId>
+            <artifactId>graphql-dgs-spring-boot-starter</artifactId>
+            <version>3.12.1</version>
+        </dependency>
+
+        <!-- Kotlin dependencies -->
+        <dependency>
+            <groupId>com.fasterxml.jackson.module</groupId>
+            <artifactId>jackson-module-kotlin</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-reflect</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib-jdk8</artifactId>
+        </dependency>
+
+        <!-- Test dependencies -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>neo4j</artifactId>
+            <version>${testcontainers.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${testcontainers.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-dependencies</artifactId>
+                <version>${spring-boot.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+
+            <plugin>
+                <groupId>io.github.deweyjose</groupId>
+                <artifactId>graphqlcodegen-maven-plugin</artifactId>
+                <version>1.8</version>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>generate</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <schemaPaths>
+                        <param>src/main/resources/schema/schema.graphqls</param>
+                    </schemaPaths>
+                    <generateClient>true</generateClient>
+                    <generateInterfaces>true</generateInterfaces>
+                    <generateDataTypes>true</generateDataTypes>
+                    <packageName>org.neo4j.graphql.examples.dgsspringboot.types</packageName>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>build-helper-maven-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <phase>generate-sources</phase>
+                        <goals>
+                            <goal>add-source</goal>
+                        </goals>
+                        <configuration>
+                            <sources>
+                                <source>${project.build.directory}/generated-sources</source>
+                            </sources>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>

examples/dgs-spring-boot/readme.adoc

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+= Example: Integration of Neo4j-GraphQL-Java into a Spring Boot application in combination with Netflix DGS
+
+== Overview
+
+This example uses the https://netflix.github.io/dgs/[Netflix DGS Framework (Domain Graph Service)]
+
+In the link:src/main/kotlin/org/neo4j/graphql/examples/dgsspringboot/config/Neo4jConfiguration.kt[Neo4jConfiguration]
+a DataFetchingInterceptor is created, which will be bound to all fields augmented by the neo4j-graphql-library.
+Its purpose is the execution of the cypher query and the transformation of the query result.
+
+In the link:src/main/kotlin/org/neo4j/graphql/examples/dgsspringboot/config/GraphQLConfiguration.kt[GraphQLConfiguration]
+the type definitions of link:src/main/resources/neo4j.graphql[schema] are loaded and augmented.
+
+In this example some fields of the enhanced type (neo4j) are extended with
+link:src/main/kotlin/org/neo4j/graphql/examples/dgsspringboot/datafetcher/AdditionalDataFetcher.kt[custom data fetcher] whose link:src/main/resources/schema/schema.graphqls[schema is separately defined].
+
+With This in place you can
+
+== Run the example
+
+1. link:src/main/resources/application.yaml[configure your neo4j db] or use a public one
+2. run the link:src/main/kotlin/org/neo4j/graphql/examples/dgsspringboot/DgsSpringBootApplication.kt[spring boot application]
+3. open http://localhost:8080/graphiql to run some graphql queries e.g. try:
+
+```graphql
+query{
+  other
+  movie (first: 3){
+    title
+    bar
+    javaData {
+      name
+    }
+  }
+}
+```

examples/dgs-spring-boot/src/main/kotlin/org/neo4j/graphql/examples/dgsspringboot/DgsSpringBootApplication.kt

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+package org.neo4j.graphql.examples.dgsspringboot
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+
+@SpringBootApplication
+open class DgsSpringBootApplication
+
+fun main(args: Array<String>) {
+    runApplication<DgsSpringBootApplication>(*args)
+}

examples/dgs-spring-boot/src/main/kotlin/org/neo4j/graphql/examples/dgsspringboot/config/GraphQLConfiguration.kt

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+package org.neo4j.graphql.examples.dgsspringboot.config
+
+import com.netflix.graphql.dgs.DgsCodeRegistry
+import com.netflix.graphql.dgs.DgsComponent
+import com.netflix.graphql.dgs.DgsRuntimeWiring
+import com.netflix.graphql.dgs.DgsTypeDefinitionRegistry
+import graphql.schema.GraphQLCodeRegistry
+import graphql.schema.idl.RuntimeWiring
+import graphql.schema.idl.SchemaParser
+import graphql.schema.idl.TypeDefinitionRegistry
+import org.neo4j.graphql.DataFetchingInterceptor
+import org.neo4j.graphql.SchemaBuilder
+import org.springframework.beans.factory.annotation.Autowired
+import org.springframework.beans.factory.annotation.Value
+import org.springframework.core.io.Resource
+import javax.annotation.PostConstruct
+
+
+/**
+ * Configuration of the GraphQL schemas
+ */
+@DgsComponent
+open class GraphQLConfiguration {
+
+    @Value("classpath:neo4j.graphql")
+    lateinit var graphQl: Resource
+
+    @Autowired(required = false)
+    lateinit var dataFetchingInterceptor: DataFetchingInterceptor
+
+    lateinit var schemaBuilder: SchemaBuilder
+
+    @PostConstruct
+    fun postConstruct() {
+        val schema = graphQl.inputStream.bufferedReader().use { it.readText() }
+        val typeDefinitionRegistry = SchemaParser().parse(schema)
+        schemaBuilder = SchemaBuilder(typeDefinitionRegistry)
+        schemaBuilder.augmentTypes()
+    }
+
+    @DgsTypeDefinitionRegistry
+    fun registry(): TypeDefinitionRegistry {
+        return schemaBuilder.typeDefinitionRegistry
+    }
+
+    @DgsCodeRegistry
+    fun codeRegistry(codeRegistryBuilder: GraphQLCodeRegistry.Builder, registry: TypeDefinitionRegistry): GraphQLCodeRegistry.Builder {
+        schemaBuilder.registerDataFetcher(codeRegistryBuilder, dataFetchingInterceptor, registry)
+        return codeRegistryBuilder
+    }
+
+    @DgsRuntimeWiring
+    fun runtimeWiring(builder: RuntimeWiring.Builder): RuntimeWiring.Builder {
+        schemaBuilder.registerTypeNameResolver(builder)
+        schemaBuilder.registerScalars(builder)
+        return builder
+    }
+}

examples/dgs-spring-boot/src/main/kotlin/org/neo4j/graphql/examples/dgsspringboot/config/Neo4jConfiguration.kt

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+package org.neo4j.graphql.examples.dgsspringboot.config
+
+import graphql.schema.*
+import org.neo4j.driver.Driver
+import org.neo4j.driver.SessionConfig
+import org.neo4j.graphql.Cypher
+import org.neo4j.graphql.DataFetchingInterceptor
+import org.springframework.beans.factory.annotation.Value
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+import java.math.BigDecimal
+import java.math.BigInteger
+
+/**
+ * Configuration of the DataFetchingInterceptor
+ */
+@Configuration
+open class Neo4jConfiguration {
+
+    /**
+     * This interceptor is bound to all the graphql fields generated by the neo4j-graphql-library.
+     * Its purpose is the execution of the cypher query and the transformation of the query result.
+     */
+    @Bean
+    open fun dataFetchingInterceptor(driver: Driver, @Value("\${database}") database: String): DataFetchingInterceptor {
+        return object : DataFetchingInterceptor {
+            override fun fetchData(env: DataFetchingEnvironment, delegate: DataFetcher<Cypher>): Any? {
+                val (cypher, params, type, variable) = delegate.get(env)
+
+                return driver.session(SessionConfig.forDatabase(database)).writeTransaction { tx ->
+                    val boltParams = params.mapValues { toBoltValue(it.value) }
+                    val result = tx.run(cypher, boltParams)
+                    if (isListType(type)) {
+                        result.list()
+                            .map { record -> record.get(variable).asObject() }
+                    } else {
+                        result.list()
+                            .map { record -> record.get(variable).asObject() }
+                            .firstOrNull() ?: emptyMap<String, Any>()
+                    }
+                }
+            }
+        }
+    }
+
+    companion object {
+        private fun toBoltValue(value: Any?) = when (value) {
+            is BigInteger -> value.longValueExact()
+            is BigDecimal -> value.toDouble()
+            else -> value
+        }
+
+        private fun isListType(type: GraphQLType?): Boolean = when (type) {
+            is GraphQLList -> true
+            is GraphQLNonNull -> isListType(type.wrappedType)
+            else -> false
+        }
+    }
+}

examples/dgs-spring-boot/src/main/kotlin/org/neo4j/graphql/examples/dgsspringboot/datafetcher/AdditionalDataFetcher.kt

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+package org.neo4j.graphql.examples.dgsspringboot.datafetcher
+
+import com.netflix.graphql.dgs.DgsComponent
+import com.netflix.graphql.dgs.DgsData
+import graphql.schema.DataFetchingEnvironment
+import org.neo4j.graphql.examples.dgsspringboot.types.types.JavaData
+import java.util.*
+
+
+@DgsComponent
+class AdditionalDataFetcher {
+    @DgsData(parentType = "Movie", field = "bar")
+    fun bar(): String {
+        return "foo"
+    }
+
+    @DgsData(parentType = "Movie", field = "javaData")
+    fun javaData(env: DataFetchingEnvironment): List<JavaData> {
+        val title = env.getSource<Map<String, *>>()["title"]
+        return Collections.singletonList(JavaData("test $title"))
+    }
+
+    @DgsData(parentType = "Query", field = "other")
+    fun other(): String {
+        return "other"
+    }
+}

examples/dgs-spring-boot/src/main/resources/application.yaml

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+org:
+  neo4j:
+    driver:
+      uri: bolt://demo.neo4jlabs.com:7687
+      authentication:
+        username: movies
+        password: movies
+      config :
+        encrypted : true
+database: movies

examples/dgs-spring-boot/src/main/resources/neo4j.graphql

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+type Movie {
+  title: String
+}

examples/dgs-spring-boot/src/main/resources/schema/schema.graphqls

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+extend type Movie {
+    bar: String @ignore
+    javaData: [JavaData!] @ignore
+}
+
+type JavaData {
+    name: String
+}
+
+extend type Query {
+    other: String
+}