feature: abstract away creation of GraphQL context (#346)

Abstracts creation of GraphQL context by introducing GraphQLContextFactory interface and provides default WebFilter that utilizes it to populate GraphQL context in the reactor subscriber context.

Author: dariuszkuc

examples/spring/src/main/kotlin/com/expediagroup/graphql/sample/context/MyGraphQLContextFactory.kt

@@ -0,0 +1,18 @@
+package com.expediagroup.graphql.sample.context
+
+import com.expediagroup.graphql.spring.execution.GraphQLContextFactory
+import org.springframework.http.server.reactive.ServerHttpRequest
+import org.springframework.http.server.reactive.ServerHttpResponse
+import org.springframework.stereotype.Component
+
+/**
+ * [GraphQLContextFactory] that generates [MyGraphQLContext] that will be available when processing GraphQL requests.
+ */
+@Component
+class MyGraphQLContextFactory: GraphQLContextFactory<MyGraphQLContext> {
+
+    override fun generateContext(request: ServerHttpRequest, response: ServerHttpResponse): MyGraphQLContext = MyGraphQLContext(
+            myCustomValue = request.headers.getFirst("MyHeader") ?: "defaultContext",
+            request = request,
+            response = response)
+}

graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/GraphQLAutoConfiguration.kt

@@ -17,6 +17,11 @@
 package com.expediagroup.graphql.spring
 
 import com.expediagroup.graphql.spring.exception.KotlinDataFetcherExceptionHandler
+import com.expediagroup.graphql.spring.execution.ContextWebFilter
+import com.expediagroup.graphql.spring.execution.EmptyContextFactory
+import com.expediagroup.graphql.spring.execution.GraphQLContextFactory
+import com.expediagroup.graphql.spring.execution.QueryHandler
+import com.expediagroup.graphql.spring.execution.SimpleQueryHandler
 import graphql.GraphQL
 import graphql.execution.AsyncExecutionStrategy
 import graphql.execution.AsyncSerialExecutionStrategy
@@ -31,6 +36,7 @@ import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
 import org.springframework.context.annotation.Import
+import org.springframework.web.server.WebFilter
 import java.util.Optional
 
 /**
@@ -79,4 +85,11 @@ class GraphQLAutoConfiguration {
     @Bean
     @ConditionalOnMissingBean
     fun graphQLQueryHandler(graphql: GraphQL): QueryHandler = SimpleQueryHandler(graphql)
+
+    @Bean
+    @ConditionalOnMissingBean
+    fun graphQLContextFactory(): GraphQLContextFactory<*> = EmptyContextFactory
+
+    @Bean
+    fun contextWebFilter(graphQLContextFactory: GraphQLContextFactory<*>): WebFilter = ContextWebFilter(graphQLContextFactory)
 }

graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/RoutesConfiguration.kt

@@ -17,6 +17,7 @@
 package com.expediagroup.graphql.spring
 
 import com.expediagroup.graphql.extensions.print
+import com.expediagroup.graphql.spring.execution.QueryHandler
 import com.expediagroup.graphql.spring.model.GraphQLRequest
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.type.MapType

graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/SubscriptionAutoConfiguration.kt

@@ -16,6 +16,8 @@
 
 package com.expediagroup.graphql.spring
 
+import com.expediagroup.graphql.spring.execution.SimpleSubscriptionHandler
+import com.expediagroup.graphql.spring.execution.SubscriptionHandler
 import com.expediagroup.graphql.spring.operations.Subscription
 import com.fasterxml.jackson.databind.ObjectMapper
 import graphql.GraphQL

examples/spring/src/main/kotlin/com/expediagroup/graphql/sample/context/MyGraphQLContextWebFilter.kt renamed to graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/execution/ContextWebFilter.kt

@@ -14,27 +14,31 @@
  * limitations under the License.
  */
 
-package com.expediagroup.graphql.sample.context
+package com.expediagroup.graphql.spring.execution
 
-import com.expediagroup.graphql.spring.GRAPHQL_CONTEXT_KEY
-import org.springframework.stereotype.Component
+import org.springframework.core.Ordered
+import org.springframework.core.annotation.Order
 import org.springframework.web.server.ServerWebExchange
 import org.springframework.web.server.WebFilter
 import org.springframework.web.server.WebFilterChain
 import reactor.core.publisher.Mono
 
 /**
- * Simple WebFilter that creates custom [MyGraphQLContext] and adds its to the SubscriberContext.
+ * [org.springframework.core.Ordered] value used for the [ContextWebFilter] order in which it will be applied to the incoming requests.
  */
-@Component
-class MyGraphQLContextWebFilter : WebFilter {
+const val GRAPHQL_CONTEXT_FILTER_ODER = 0
 
+/**
+ * Default web filter that populates GraphQL context in the reactor subscriber context.
+ */
+@Order(GRAPHQL_CONTEXT_FILTER_ODER)
+class ContextWebFilter(private val contextFactory: GraphQLContextFactory<Any>) : WebFilter, Ordered {
+
+    @Suppress("ForbiddenVoid")
     override fun filter(exchange: ServerWebExchange, chain: WebFilterChain): Mono<Void> {
-        val myValue = exchange.request.headers.getFirst("MyHeader") ?: "defaultContext"
-        val customContext = MyGraphQLContext(
-            myCustomValue = myValue,
-            request = exchange.request,
-            response = exchange.response)
-        return chain.filter(exchange).subscriberContext { it.put(GRAPHQL_CONTEXT_KEY, customContext) }
+        val context = contextFactory.generateContext(exchange.request, exchange.response)
+        return chain.filter(exchange).subscriberContext { it.put(GRAPHQL_CONTEXT_KEY, context) }
     }
+
+    override fun getOrder(): Int = GRAPHQL_CONTEXT_FILTER_ODER
 }

graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/execution/GraphQLContextFactory.kt

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2019 Expedia, Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.expediagroup.graphql.spring.execution
+
+import graphql.GraphQLContext
+import org.springframework.http.server.reactive.ServerHttpRequest
+import org.springframework.http.server.reactive.ServerHttpResponse
+
+/**
+ * Reactor SubscriberContext key for storing GraphQL context.
+ */
+const val GRAPHQL_CONTEXT_KEY = "graphQLContext"
+
+/**
+ * Factory that generates GraphQL context.
+ */
+interface GraphQLContextFactory<out T : Any> {
+
+    /**
+     * Generate GraphQL context based on the incoming request and the corresponding response.
+     */
+    fun generateContext(request: ServerHttpRequest, response: ServerHttpResponse): T
+}
+
+/**
+ * Default context factory that generates empty GraphQL context.
+ */
+internal object EmptyContextFactory : GraphQLContextFactory<GraphQLContext> {
+
+    override fun generateContext(request: ServerHttpRequest, response: ServerHttpResponse): GraphQLContext = GraphQLContext.newContext().build()
+}

graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/QueryHandler.kt renamed to graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/execution/QueryHandler.kt

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.expediagroup.graphql.spring
+package com.expediagroup.graphql.spring.execution
 
 import com.expediagroup.graphql.spring.exception.SimpleKotlinGraphQLError
 import com.expediagroup.graphql.spring.model.GraphQLRequest
@@ -27,11 +27,6 @@ import kotlinx.coroutines.future.await
 import kotlinx.coroutines.reactor.ReactorContext
 import kotlin.coroutines.coroutineContext
 
-/**
- * Reactor SubscriberContext key for storing GraphQL context.
- */
-const val GRAPHQL_CONTEXT_KEY = "graphQLContext"
-
 /**
  * GraphQL query handler.
  */

graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/SubscriptionHandler.kt renamed to graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/execution/SubscriptionHandler.kt

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.expediagroup.graphql.spring
+package com.expediagroup.graphql.spring.execution
 
 import com.expediagroup.graphql.spring.model.GraphQLRequest
 import com.expediagroup.graphql.spring.model.GraphQLResponse

graphql-kotlin-spring-server/src/test/kotlin/com/expediagroup/graphql/spring/federation/FederationConfigurationTest.kt renamed to graphql-kotlin-spring-server/src/test/kotlin/com/expediagroup/graphql/spring/FederationConfigurationTest.kt

@@ -1,4 +1,4 @@
-package com.expediagroup.graphql.spring.federation
+package com.expediagroup.graphql.spring
 
 import com.expediagroup.graphql.SchemaGeneratorConfig
 import com.expediagroup.graphql.TopLevelObject
@@ -9,8 +9,8 @@ import com.expediagroup.graphql.federation.directives.ExternalDirective
 import com.expediagroup.graphql.federation.directives.FieldSet
 import com.expediagroup.graphql.federation.directives.KeyDirective
 import com.expediagroup.graphql.federation.execution.FederatedTypeRegistry
-import com.expediagroup.graphql.spring.GraphQLAutoConfiguration
-import com.expediagroup.graphql.spring.QueryHandler
+import com.expediagroup.graphql.spring.execution.GraphQLContextFactory
+import com.expediagroup.graphql.spring.execution.QueryHandler
 import com.expediagroup.graphql.spring.operations.Query
 import com.expediagroup.graphql.toSchema
 import com.fasterxml.jackson.databind.ObjectMapper
@@ -35,11 +35,11 @@ class FederationConfigurationTest {
     @Test
     fun `verify federated schema auto configuration`() {
         contextRunner.withUserConfiguration(FederatedConfiguration::class.java)
-            .withPropertyValues("graphql.packages=com.expediagroup.graphql.spring.federation", "graphql.federation.enabled=true")
+            .withPropertyValues("graphql.packages=com.expediagroup.graphql.spring", "graphql.federation.enabled=true")
             .run { ctx ->
                 assertThat(ctx).hasSingleBean(SchemaGeneratorConfig::class.java)
                 val schemaGeneratorConfig = ctx.getBean(SchemaGeneratorConfig::class.java)
-                assertEquals(listOf("com.expediagroup.graphql.spring.federation"), schemaGeneratorConfig.supportedPackages)
+                assertEquals(listOf("com.expediagroup.graphql.spring"), schemaGeneratorConfig.supportedPackages)
 
                 assertThat(ctx).hasSingleBean(GraphQLSchema::class.java)
                 val schema = ctx.getBean(GraphQLSchema::class.java)
@@ -60,6 +60,7 @@ class FederationConfigurationTest {
 
                 assertThat(ctx).hasSingleBean(GraphQL::class.java)
                 assertThat(ctx).hasSingleBean(QueryHandler::class.java)
+                assertThat(ctx).hasSingleBean(GraphQLContextFactory::class.java)
             }
     }
 
@@ -79,12 +80,14 @@ class FederationConfigurationTest {
 
                 assertThat(ctx).hasSingleBean(GraphQL::class.java)
                 assertThat(ctx).hasSingleBean(QueryHandler::class.java)
+                assertThat(ctx).hasSingleBean(GraphQLContextFactory::class.java)
             }
     }
 
     @Configuration
     class FederatedConfiguration {
 
+        // in regular apps object mapper will be created by JacksonAutoConfiguration
         @Bean
         fun objectMapper(): ObjectMapper = jacksonObjectMapper()
 
@@ -95,6 +98,7 @@ class FederationConfigurationTest {
     @Configuration
     class CustomFederatedConfiguration {
 
+        // in regular apps object mapper will be created by JacksonAutoConfiguration
         @Bean
         fun objectMapper(): ObjectMapper = jacksonObjectMapper()
 

graphql-kotlin-spring-server/src/test/kotlin/com/expediagroup/graphql/spring/base/SchemaConfigurationTest.kt renamed to graphql-kotlin-spring-server/src/test/kotlin/com/expediagroup/graphql/spring/SchemaConfigurationTest.kt

@@ -1,9 +1,9 @@
-package com.expediagroup.graphql.spring.base
+package com.expediagroup.graphql.spring
 
 import com.expediagroup.graphql.SchemaGeneratorConfig
 import com.expediagroup.graphql.TopLevelObject
-import com.expediagroup.graphql.spring.GraphQLAutoConfiguration
-import com.expediagroup.graphql.spring.QueryHandler
+import com.expediagroup.graphql.spring.execution.GraphQLContextFactory
+import com.expediagroup.graphql.spring.execution.QueryHandler
 import com.expediagroup.graphql.spring.operations.Query
 import com.expediagroup.graphql.toSchema
 import com.fasterxml.jackson.databind.ObjectMapper
@@ -13,6 +13,7 @@ import graphql.execution.instrumentation.Instrumentation
 import graphql.execution.instrumentation.tracing.TracingInstrumentation
 import graphql.schema.GraphQLSchema
 import graphql.schema.GraphQLTypeUtil
+import io.mockk.mockk
 import org.assertj.core.api.AssertionsForInterfaceTypes.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.boot.autoconfigure.AutoConfigurations
@@ -31,11 +32,11 @@ class SchemaConfigurationTest {
     @Test
     fun `verify schema auto configuration`() {
         contextRunner.withUserConfiguration(BasicConfiguration::class.java)
-            .withPropertyValues("graphql.packages=com.expediagroup.graphql.spring.base")
+            .withPropertyValues("graphql.packages=com.expediagroup.graphql.spring")
             .run { ctx ->
                 assertThat(ctx).hasSingleBean(SchemaGeneratorConfig::class.java)
                 val schemaGeneratorConfig = ctx.getBean(SchemaGeneratorConfig::class.java)
-                assertEquals(listOf("com.expediagroup.graphql.spring.base"), schemaGeneratorConfig.supportedPackages)
+                assertEquals(listOf("com.expediagroup.graphql.spring"), schemaGeneratorConfig.supportedPackages)
 
                 assertThat(ctx).hasSingleBean(GraphQLSchema::class.java)
                 val schema = ctx.getBean(GraphQLSchema::class.java)
@@ -56,6 +57,7 @@ class SchemaConfigurationTest {
                 assertNotNull(result["extensions"])
 
                 assertThat(ctx).hasSingleBean(QueryHandler::class.java)
+                assertThat(ctx).hasSingleBean(GraphQLContextFactory::class.java)
             }
     }
 
@@ -78,12 +80,17 @@ class SchemaConfigurationTest {
                     .isSameAs(customConfiguration.myGraphQL())
 
                 assertThat(ctx).hasSingleBean(QueryHandler::class.java)
+
+                assertThat(ctx).hasSingleBean(GraphQLContextFactory::class.java)
+                assertThat(ctx).getBean(GraphQLContextFactory::class.java)
+                    .isSameAs(customConfiguration.myCustomContextFactory())
             }
     }
 
     @Configuration
     class BasicConfiguration {
 
+        // in regular apps object mapper will be created by JacksonAutoConfiguration
         @Bean
         fun objectMapper(): ObjectMapper = jacksonObjectMapper()
 
@@ -97,6 +104,7 @@ class SchemaConfigurationTest {
     @Configuration
     class CustomConfiguration {
 
+        // in regular apps object mapper will be created by JacksonAutoConfiguration
         @Bean
         fun objectMapper(): ObjectMapper = jacksonObjectMapper()
 
@@ -115,6 +123,9 @@ class SchemaConfigurationTest {
         fun myGraphQL(): GraphQL = GraphQL.newGraphQL(mySchema())
             .instrumentation(TracingInstrumentation())
             .build()
+
+        @Bean
+        fun myCustomContextFactory(): GraphQLContextFactory<Map<String, Any>> = mockk()
     }
 
     class BasicQuery : Query {