fix Ktor server DataLoader example usage (#1786)

Author: dariuszkuc

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Expedia, Inc
+ * Copyright 2023 Expedia, Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,17 +16,22 @@
 
 package com.expediagroup.graphql.examples.server.ktor.schema
 
+import com.expediagroup.graphql.examples.server.ktor.schema.dataloaders.BookDataLoader
 import com.expediagroup.graphql.examples.server.ktor.schema.models.Book
 import com.expediagroup.graphql.generator.annotations.GraphQLDescription
 import com.expediagroup.graphql.server.operations.Query
+import graphql.schema.DataFetchingEnvironment
+import java.util.concurrent.CompletableFuture
 
 /**
  * Provide Search options for book data
  */
 class BookQueryService : Query {
     @GraphQLDescription("Return list of books based on BookSearchParameter options")
     @Suppress("unused")
-    fun searchBooks(params: BookSearchParameters) = Book.search(params.ids)
+    fun searchBooks(params: BookSearchParameters, dfe: DataFetchingEnvironment): CompletableFuture<List<Book>> =
+        dfe.getDataLoader<Int, Book>(BookDataLoader.dataLoaderName)
+            .loadMany(params.ids)
 }
 
 data class BookSearchParameters(val ids: List<Int>)

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Expedia, Inc
+ * Copyright 2023 Expedia, Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,11 +16,16 @@
 
 package com.expediagroup.graphql.examples.server.ktor.schema
 
+import com.expediagroup.graphql.examples.server.ktor.schema.dataloaders.CourseDataLoader
 import com.expediagroup.graphql.examples.server.ktor.schema.models.Course
 import com.expediagroup.graphql.server.operations.Query
+import graphql.schema.DataFetchingEnvironment
+import java.util.concurrent.CompletableFuture
 
 class CourseQueryService : Query {
-    fun searchCourses(params: CourseSearchParameters) = Course.search(params.ids)
+    fun searchCourses(params: CourseSearchParameters, dfe: DataFetchingEnvironment): CompletableFuture<List<Course>> =
+        dfe.getDataLoader<Int, Course>(CourseDataLoader.dataLoaderName)
+            .loadMany(params.ids)
 }
 
 data class CourseSearchParameters(val ids: List<Int>)

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Expedia, Inc
+ * Copyright 2023 Expedia, Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,14 +16,16 @@
 
 package com.expediagroup.graphql.examples.server.ktor.schema
 
+import com.expediagroup.graphql.examples.server.ktor.schema.dataloaders.UniversityDataLoader
 import com.expediagroup.graphql.examples.server.ktor.schema.models.University
 import com.expediagroup.graphql.server.operations.Query
-import graphql.GraphQLException
+import graphql.schema.DataFetchingEnvironment
+import java.util.concurrent.CompletableFuture
 
 class UniversityQueryService : Query {
-    @Throws(GraphQLException::class)
-    suspend fun searchUniversities(params: UniversitySearchParameters): List<University> =
-        University.search(params.ids)
+    fun searchUniversities(params: UniversitySearchParameters, dfe: DataFetchingEnvironment): CompletableFuture<List<University>> =
+        dfe.getDataLoader<Int, University>(UniversityDataLoader.dataLoaderName)
+            .loadMany(params.ids)
 }
 
 data class UniversitySearchParameters(val ids: List<Int>)

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

@@ -23,18 +23,12 @@ import graphql.GraphQLContext
 import org.dataloader.DataLoaderFactory
 import java.util.concurrent.CompletableFuture
 
-val BookDataLoader = object : KotlinDataLoader<List<Int>, List<Book>> {
-    override val dataLoaderName = "BATCH_BOOK_LOADER"
+val BookDataLoader = object : KotlinDataLoader<Int, Book?> {
+    override val dataLoaderName = "BOOK_LOADER"
     override fun getDataLoader(graphQLContext: GraphQLContext) =
-        DataLoaderFactory.newDataLoader<List<Int>, List<Book>> { ids ->
+        DataLoaderFactory.newDataLoader { ids ->
             CompletableFuture.supplyAsync {
-                val allBooks = runBlocking { Book.search(ids.flatten()).toMutableList() }
-                // produce lists of results from returned books
-                ids.fold(mutableListOf()) { acc: MutableList<List<Book>>, idSet ->
-                    val matchingBooks = allBooks.filter { idSet.contains(it.id) }
-                    acc.add(matchingBooks)
-                    acc
-                }
+                runBlocking { Book.search(ids).toMutableList() }
             }
         }
 }

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

@@ -26,7 +26,7 @@ import java.util.concurrent.CompletableFuture
 val CourseDataLoader = object : KotlinDataLoader<Int, Course?> {
     override val dataLoaderName = "COURSE_LOADER"
     override fun getDataLoader(graphQLContext: GraphQLContext) =
-        DataLoaderFactory.newDataLoader<Int, Course?> { ids ->
+        DataLoaderFactory.newDataLoader { ids ->
             CompletableFuture.supplyAsync {
                 runBlocking { Course.search(ids).toMutableList() }
             }

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

@@ -26,7 +26,7 @@ import java.util.concurrent.CompletableFuture
 val UniversityDataLoader = object : KotlinDataLoader<Int, University?> {
     override val dataLoaderName = "UNIVERSITY_LOADER"
     override fun getDataLoader(graphQLContext: GraphQLContext) =
-        DataLoaderFactory.newDataLoader<Int, University?> { ids ->
+        DataLoaderFactory.newDataLoader { ids ->
             CompletableFuture.supplyAsync {
                 runBlocking { University.search(ids).toMutableList() }
             }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 Expedia, Inc
+ * Copyright 2023 Expedia, Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@ package com.expediagroup.graphql.examples.server.ktor.schema.models
 import com.expediagroup.graphql.examples.server.ktor.schema.dataloaders.BookDataLoader
 import com.expediagroup.graphql.examples.server.ktor.schema.dataloaders.UniversityDataLoader
 import com.expediagroup.graphql.server.extensions.getValueFromDataLoader
+import com.expediagroup.graphql.server.extensions.getValuesFromDataLoader
 import graphql.schema.DataFetchingEnvironment
 import java.util.concurrent.CompletableFuture
 
@@ -35,7 +36,7 @@ data class Course(
     }
 
     fun books(dataFetchingEnvironment: DataFetchingEnvironment): CompletableFuture<List<Book>> {
-        return dataFetchingEnvironment.getValueFromDataLoader(BookDataLoader.dataLoaderName, bookIds)
+        return dataFetchingEnvironment.getValuesFromDataLoader(BookDataLoader.dataLoaderName, bookIds)
     }
 
     companion object {