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adamsz-lumeAdam Firen
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Adam Firen
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add ktor example (#951)
* add ktor example * add the playground endpoint * implement requested changes for the ktor server example Co-authored-by: Adam Firen <[email protected]>
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‎examples/README.md‎

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@@ -4,5 +4,6 @@ Example apps that use `graphql-kotlin` libraries to test and demonstrate usages.
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* [client](https://github.com/ExpediaGroup/graphql-kotlin/tree/master/examples/client) - Example GraphQL Kotlin Client projects using Gradle and Maven together with a simple server to run against.
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* [federation](https://github.com/ExpediaGroup/graphql-kotlin/tree/master/examples/federation) - Example Spring Boot apps generating federated GraphQL schemas and an Apollo Gateway in NodeJS that exposes the merged federated schema. Please refer to the README files for details on how to run each federated service.
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* [ktor-server](https://github.com/ExpediaGroup/graphql-kotlin/tree/master/examples/ktor-server) - Example GraphQL server using Ktor
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* [spark](https://github.com/ExpediaGroup/graphql-kotlin/tree/master/examples/spark) - Example GraphQL server using Spark framework
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* [spring](https://github.com/ExpediaGroup/graphql-kotlin/tree/master/examples/spring) - This is a sample Spring Boot app that uses `graphql-kotlin-spring-server` to create a reactive GraphQL web application. Please refer to the README file for details on how to run the application.

‎examples/ktor-server/README.md‎

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# GraphQL Kotlin Ktor
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[Ktor](http://ktor.io/) is an asynchronous framework for creating microservices, web applications, and more.
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### Running locally
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Build the application by running the following from examples root directory:
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```bash
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# build example
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./gradlew ktor-example:build
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```
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> NOTE: in order to ensure you use the right version of Gradle we highly recommend that you use the provided wrapper scripts
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Start the server by running `Application.kt` directly from your IDE. (Make sure that your Kotlin Compiler jvm target is 1.8 or greater.)
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Alternatively, you can start the server using Gradle.
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```bash
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cd /path/to/graphql-kotlin/examples
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./gradlew ktor-example:run
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```
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Once the app has started you can explore the example schema by opening Playground endpoint at http://localhost:5000/graphql
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#### Example query
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You can use the following example query to view several of the related models:
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```graphql
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query {
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searchCourses(params: { ids: [1,2,3] }) {
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id
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name
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books {
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title
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}
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university {
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id
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name
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}
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}
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searchUniversities(params: { ids: [1]}) {
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id
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name
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}
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}
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```
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You can also query the `longThatNeverComes` field from several of the types. This will throw and exception,
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allow you to see how the `ExecutionStrategy` handles throw exceptions in different levels of the query.

‎examples/ktor-server/build.gradle.kts‎

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val ktor_version: String by project
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val logback_version: String by project
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val slf4j_version: String by project
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description = "An Example GraphQL service served by Ktor"
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plugins {
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id("application")
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}
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application {
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mainClassName = "io.ktor.server.netty.EngineMain"
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}
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val kotlinCoroutinesVersion: String by project
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dependencies {
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implementation("io.ktor:ktor-server-core:$ktor_version")
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implementation("io.ktor:ktor-server-netty:$ktor_version")
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implementation("ch.qos.logback:logback-classic:$logback_version")
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implementation("com.expediagroup", "graphql-kotlin-schema-generator")
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implementation("org.jetbrains.kotlinx", "kotlinx-coroutines-jdk8", kotlinCoroutinesVersion)
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}

‎examples/ktor-server/gradle.properties‎

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ktor_version=1.4.2
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logback_version=1.2.1

‎examples/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/ktor/Application.kt‎

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/**
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* Copyright 2020 Expedia, Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.expediagroup.graphql.examples.ktor
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fun main(args: Array<String>): Unit = io.ktor.server.netty.EngineMain.main(args)

‎examples/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/ktor/GraphQLHandler.kt‎

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/**
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* Copyright 2020 Expedia, Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.expediagroup.graphql.examples.ktor
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import com.expediagroup.graphql.SchemaGeneratorConfig
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import com.expediagroup.graphql.TopLevelObject
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import com.expediagroup.graphql.examples.ktor.schema.BookQueryService
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import com.expediagroup.graphql.examples.ktor.schema.CourseQueryService
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import com.expediagroup.graphql.examples.ktor.schema.HelloQueryService
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import com.expediagroup.graphql.examples.ktor.schema.LoginMutationService
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import com.expediagroup.graphql.examples.ktor.schema.UniversityQueryService
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import com.expediagroup.graphql.examples.ktor.schema.models.BATCH_BOOK_LOADER_NAME
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import com.expediagroup.graphql.examples.ktor.schema.models.COURSE_LOADER_NAME
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import com.expediagroup.graphql.examples.ktor.schema.models.UNIVERSITY_LOADER_NAME
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import com.expediagroup.graphql.examples.ktor.schema.models.User
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import com.expediagroup.graphql.examples.ktor.schema.models.batchBookLoader
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import com.expediagroup.graphql.examples.ktor.schema.models.batchCourseLoader
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import com.expediagroup.graphql.examples.ktor.schema.models.batchUniversityLoader
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import com.expediagroup.graphql.toSchema
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import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
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import com.fasterxml.jackson.module.kotlin.readValue
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import graphql.ExceptionWhileDataFetching
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import graphql.ExecutionInput
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import graphql.ExecutionResult
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import graphql.GraphQL
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import io.ktor.application.ApplicationCall
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import io.ktor.request.ApplicationRequest
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import io.ktor.request.receiveText
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import io.ktor.response.respond
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import org.dataloader.DataLoaderRegistry
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import java.io.IOException
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data class AuthorizedContext(val authorizedUser: User? = null, var guestUUID: String? = null)
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class GraphQLHandler {
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companion object {
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private val config = SchemaGeneratorConfig(supportedPackages = listOf("com.expediagroup.graphql.examples"))
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private val queries = listOf(
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TopLevelObject(HelloQueryService()),
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TopLevelObject(BookQueryService()),
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TopLevelObject(CourseQueryService()),
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TopLevelObject(UniversityQueryService())
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)
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private val mutations = listOf(
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TopLevelObject(LoginMutationService())
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)
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private val graphQLSchema = toSchema(config, queries, mutations)
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val graphQL = GraphQL.newGraphQL(graphQLSchema).build()!!
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}
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private val mapper = jacksonObjectMapper()
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private val dataLoaderRegistry = DataLoaderRegistry()
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init {
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dataLoaderRegistry.register(UNIVERSITY_LOADER_NAME, batchUniversityLoader)
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dataLoaderRegistry.register(COURSE_LOADER_NAME, batchCourseLoader)
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dataLoaderRegistry.register(BATCH_BOOK_LOADER_NAME, batchBookLoader)
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}
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/**
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* Get payload from the request.
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*/
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private suspend fun getPayload(request: ApplicationRequest): Map<String, Any>? {
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return try {
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mapper.readValue<Map<String, Any>>(request.call.receiveText())
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} catch (e: IOException) {
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throw IOException("Unable to parse GraphQL payload.")
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}
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}
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/**
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* Get the variables passed in the request.
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*/
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private fun getVariables(payload: Map<String, *>) =
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payload.getOrElse("variables") { emptyMap<String, Any>() } as Map<String, Any>
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/**
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* Find attache user to context (authentication would go here)
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*/
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private fun getContext(request: ApplicationRequest): AuthorizedContext {
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val loggedInUser = User(
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email = "[email protected]",
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firstName = "Someone",
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lastName = "You Don't know",
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universityId = 4
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)
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return AuthorizedContext(loggedInUser)
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}
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/**
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* Get any errors and data from [executionResult].
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*/
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private fun getResult(executionResult: ExecutionResult): MutableMap<String, Any> {
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val result = mutableMapOf<String, Any>()
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if (executionResult.errors.isNotEmpty()) {
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// if we encounter duplicate errors while data fetching, only include one copy
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result["errors"] = executionResult.errors.distinctBy {
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if (it is ExceptionWhileDataFetching) {
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it.exception
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} else {
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it
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}
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}
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}
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try {
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// if data is null, get data will fail exceptionally
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result["data"] = executionResult.getData<Any>()
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} catch (e: Exception) {}
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return result
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}
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/**
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* Execute a query against schema
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*/
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suspend fun handle(applicationCall: ApplicationCall) {
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val payload = getPayload(applicationCall.request)
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payload?.let {
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// Execute the query against the schema
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val executionResult = graphQL.executeAsync(
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ExecutionInput.Builder()
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.query(payload["query"].toString())
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.variables(getVariables(payload))
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.dataLoaderRegistry(dataLoaderRegistry)
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.context(getContext(applicationCall.request))
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).get()
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val result = getResult(executionResult)
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// write response as json
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applicationCall.response.call.respond(mapper.writeValueAsString(result))
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}
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}
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}

‎examples/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/ktor/GraphQLModule.kt‎

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package com.expediagroup.graphql.examples.ktor
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import io.ktor.application.Application
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import io.ktor.application.call
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import io.ktor.application.install
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import io.ktor.http.ContentType
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import io.ktor.response.respondText
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import io.ktor.routing.Routing
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import io.ktor.routing.get
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import io.ktor.routing.post
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import io.ktor.routing.routing
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import java.lang.IllegalStateException
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fun Application.graphQLModule() {
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install(Routing)
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routing {
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post("graphql") {
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GraphQLHandler().handle(this.call)
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}
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get("playground") {
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this.call.respondText(buildPlaygroundHtml("graphql", "graphql"), ContentType.Text.Html)
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}
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}
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}
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private fun buildPlaygroundHtml(graphQLEndpoint: String, subscriptionsEndpoint: String) =
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Application::class.java.classLoader.getResource("graphql-playground.html")?.readText()
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?.replace("\${graphQLEndpoint}", graphQLEndpoint)
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?.replace("\${subscriptionsEndpoint}", subscriptionsEndpoint)
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?: throw IllegalStateException("graphql-playground.html cannot be found in the classpath")

‎examples/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/ktor/schema/BookQueryService.kt‎

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/**
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* Copyright 2020 Expedia, Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.expediagroup.graphql.examples.ktor.schema
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import com.expediagroup.graphql.annotations.GraphQLDescription
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import com.expediagroup.graphql.examples.ktor.schema.models.Book
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/**
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* Provide Search options for book data
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*/
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class BookQueryService {
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@GraphQLDescription("Return list of books based on BookSearchParameter options")
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@Suppress("unused")
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suspend fun searchBooks(params: BookSearchParameters) = Book.search(params.ids)
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}
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data class BookSearchParameters(val ids: List<Long>)

‎examples/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/ktor/schema/CourseQueryService.kt‎

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/**
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* Copyright 2020 Expedia, Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.expediagroup.graphql.examples.ktor.schema
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import com.expediagroup.graphql.examples.ktor.schema.models.Course
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class CourseQueryService {
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suspend fun searchCourses(params: CourseSearchParameters) = Course.search(params.ids)
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}
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data class CourseSearchParameters(val ids: List<Long>)

‎examples/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/ktor/schema/HelloQueryService.kt‎

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/**
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* Copyright 2020 Expedia, Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.expediagroup.graphql.examples.ktor.schema
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class HelloQueryService {
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fun hello() = "World!"
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}

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