Add spring boot integration example (neo4j-graphql#126)

* add spring boot integration example

* adjustments after review

core/pom.xml

@@ -0,0 +1,89 @@
+<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.neo4j</groupId>
+        <artifactId>neo4j-graphql-java-parent</artifactId>
+        <version>1.1-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>neo4j-graphql-java</artifactId>
+    <name>Neo4j GraphQL Java</name>
+    <description>GraphQL to Cypher Mapping</description>
+
+    <properties>
+        <neo4j.version>3.5.6</neo4j.version>
+        <driver.version>1.7.2</driver.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.neo4j.driver</groupId>
+            <artifactId>neo4j-java-driver</artifactId>
+            <version>${driver.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.sparkjava</groupId>
+            <artifactId>spark-core</artifactId>
+            <version>2.7.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <version>2.8.5</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.neo4j.test</groupId>
+            <artifactId>neo4j-harness</artifactId>
+            <version>${neo4j.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.neo4j</groupId>
+            <artifactId>server-api</artifactId>
+            <version>${neo4j.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.codehaus.jackson</groupId>
+            <artifactId>jackson-mapper-asl</artifactId>
+            <version>1.9.13</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java</artifactId>
+            <version>15.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.5.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.12.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.neo4j</groupId>
+            <artifactId>neo4j-cypher-dsl</artifactId>
+            <version>2020.0.1</version>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>1.2.3</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

src/test/kotlin/org/neo4j/graphql/ParserTests.kt → core/src/test/kotlin/org/neo4j/graphql/ParserTests.kt

@@ -57,4 +57,4 @@ input _RatedInput { rating:Int }
         assertEquals(true, typeDefinitionRegistry.getType("_MovieFilter").isPresent)
 
     }
-}
+}

examples/graphql-spring-boot/pom.xml

@@ -0,0 +1,102 @@
+<?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>1.1-SNAPSHOT</version>
+	</parent>
+
+	<groupId>org.neo4j.graphql.examples</groupId>
+	<artifactId>graphql-spring-boot</artifactId>
+
+	<name>Example - graphql-spring-boot</name>
+	<description>Example for using neo4j-graphql-java with Spring Boot</description>
+
+	<properties>
+		<testcontainers.version>1.14.3</testcontainers.version>
+	</properties>
+
+	<dependencies>
+		<!-- spring dependencies -->
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-configuration-processor</artifactId>
+			<optional>true</optional>
+		</dependency>
+
+		<!-- neo4j driver + the neo4j-graphql-java library -->
+		<dependency>
+			<groupId>org.neo4j.driver</groupId>
+			<artifactId>neo4j-java-driver-spring-boot-starter</artifactId>
+			<version>4.1.1.0</version>
+		</dependency>
+		<dependency>
+			<groupId>org.neo4j</groupId>
+			<artifactId>neo4j-graphql-java</artifactId>
+			<version>1.1-SNAPSHOT</version>
+		</dependency>
+
+		<!-- a spring graphql library -->
+		<dependency>
+			<groupId>com.expediagroup</groupId>
+			<artifactId>graphql-kotlin-spring-server</artifactId>
+			<version>3.6.2</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>2.3.3.RELEASE</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>
+		</plugins>
+	</build>
+</project>

examples/graphql-spring-boot/readme.adoc

@@ -0,0 +1,21 @@
+= Example: Integration of Neo4j-GraphQL-Java into a Spring Boot application
+
+== Overview
+This example uses the https://expediagroup.github.io/graphql-kotlin/[graphql-kotlin library]
+
+In the link:src/main/kotlin/org/neo4j/graphql/examples/graphqlspringboot/config/Neo4jConfiguration.kt[Neo4jConfiguration]
+a DataFetchingInterceptor is created, which will be 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.
+
+In the link:src/main/kotlin/org/neo4j/graphql/examples/graphqlspringboot/config/GraphQLConfiguration.kt[GraphQLConfiguration]
+the link:src/main/resources/schema.graphqls[schema] to be enhanced by the library is loaded as `neo4jSchema`.
+Additionally a `springSchema` is generated which is generated from the methods defined in
+link:src/main/kotlin/org/neo4j/graphql/examples/graphqlspringboot/controller/AdditionalQueries.kt[AdditionalQueries].
+
+The `springSchema` and the `neo4jSchema` are merged to a single graphql schema exposed by the app.
+
+== Run the example
+
+1. link:src/main/resources/application.yaml[configue your neo4j db]
+2. run the link:src/main/kotlin/org/neo4j/graphql/examples/graphqlspringboot/GraphqlSpringBootApplication.kt[spring boot application]
+3. open http://localhost:8080/playground to run some graphql queries

examples/graphql-spring-boot/src/main/kotlin/org/neo4j/graphql/examples/graphqlspringboot/GraphqlSpringBootApplication.kt

@@ -0,0 +1,11 @@
+package org.neo4j.graphql.examples.graphqlspringboot
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+
+@SpringBootApplication
+open class GraphqlSpringBootApplication
+
+fun main(args: Array<String>) {
+    runApplication<GraphqlSpringBootApplication>(*args)
+}

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

@@ -0,0 +1,118 @@
+package org.neo4j.graphql.examples.graphqlspringboot.config
+
+import com.expediagroup.graphql.SchemaGeneratorConfig
+import com.expediagroup.graphql.TopLevelObject
+import com.expediagroup.graphql.extensions.print
+import com.expediagroup.graphql.generator.SchemaGenerator
+import com.expediagroup.graphql.spring.operations.Mutation
+import com.expediagroup.graphql.spring.operations.Query
+import com.expediagroup.graphql.spring.operations.Subscription
+import graphql.schema.GraphQLObjectType
+import graphql.schema.GraphQLSchema
+import org.neo4j.graphql.DataFetchingInterceptor
+import org.neo4j.graphql.SchemaBuilder
+import org.neo4j.graphql.SchemaConfig
+import org.slf4j.LoggerFactory
+import org.springframework.aop.framework.Advised
+import org.springframework.aop.support.AopUtils
+import org.springframework.beans.factory.annotation.Autowired
+import org.springframework.beans.factory.annotation.Value
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+import org.springframework.context.annotation.Primary
+import org.springframework.core.io.Resource
+import java.util.*
+
+/**
+ * Configuration of the GraphQL schemas
+ */
+@Configuration
+open class GraphQLConfiguration {
+    private val logger = LoggerFactory.getLogger(GraphQLConfiguration::class.java)
+
+    /**
+     * This generates the augmented neo4j schema
+     */
+    @Bean
+    open fun neo4jSchema(
+            @Value("classpath:schema.graphql") graphQl: Resource,
+            @Autowired(required = false) dataFetchingInterceptor: DataFetchingInterceptor
+    ): GraphQLSchema {
+        val schema = graphQl.inputStream.bufferedReader().use { it.readText() }
+        return SchemaBuilder.buildSchema(schema, SchemaConfig(), dataFetchingInterceptor)
+    }
+
+    /**
+     * This generates the spring schema provided generated by the `graphql-kotlin-spring-server`
+     */
+    @Bean
+    open fun springSchema(
+            queries: Optional<List<Query>>,
+            mutations: Optional<List<Mutation>>,
+            subscriptions: Optional<List<Subscription>>,
+            schemaConfig: SchemaGeneratorConfig
+    ): GraphQLSchema {
+        val generator = SchemaGenerator(schemaConfig)
+        return generator.use {
+            it.generateSchema(
+                    queries = queries.orElse(emptyList()).toTopLevelObjects(),
+                    mutations = mutations.orElse(emptyList()).toTopLevelObjects(),
+                    subscriptions = subscriptions.orElse(emptyList()).toTopLevelObjects()
+            )
+        }
+    }
+
+    /**
+     * This merges the springSchema and the neo4jSchema
+     */
+    @Bean
+    @Primary
+    open fun mergedSchema(neo4jSchema: GraphQLSchema, springSchema: GraphQLSchema): GraphQLSchema {
+        val builder: GraphQLSchema.Builder = GraphQLSchema.newSchema(neo4jSchema)
+
+        val springCodeRegistry = springSchema.codeRegistry
+        builder.codeRegistry(neo4jSchema.codeRegistry.transform { crBuilder ->
+            crBuilder.dataFetchers(springCodeRegistry)
+            crBuilder.typeResolvers(springCodeRegistry)
+        })
+
+        val allTypes = (neo4jSchema.typeMap + springSchema.typeMap).toMutableMap()
+        allTypes.replace("Query", mergeType(neo4jSchema.queryType, springSchema.queryType))
+        allTypes.replace("Mutation", mergeType(neo4jSchema.mutationType, springSchema.mutationType))
+
+        allTypes["Query"]?.let { builder.query(it as GraphQLObjectType) }
+        allTypes["Mutation"]?.let { builder.mutation(it as GraphQLObjectType) }
+        allTypes["Subscription"]?.let { builder.subscription(it as GraphQLObjectType) }
+
+        builder.clearAdditionalTypes()
+        allTypes.values.forEach { builder.additionalType(it) }
+
+        val schema = builder.build()
+
+        logger.info("\n${schema.print()}")
+
+        return schema
+    }
+
+    private fun mergeType(t1: GraphQLObjectType?, t2: GraphQLObjectType?): GraphQLObjectType? {
+        if (t1 == null) {
+            return t2
+        }
+        if (t2 == null) {
+            return t1
+        }
+        val builder = GraphQLObjectType.newObject(t1)
+        t2.fieldDefinitions.forEach { builder.field(it) }
+        return builder.build()
+    }
+
+    // This was copied over from {@link com.expediagroup.graphql.spring.extensions.generatorExtensions.kt }
+    private fun List<Any>.toTopLevelObjects() = this.map {
+        val klazz = if (AopUtils.isAopProxy(it) && it is Advised) {
+            it.targetSource.target!!::class
+        } else {
+            it::class
+        }
+        TopLevelObject(it, klazz)
+    }
+}