From d214ac9cc1b10028b6dfe26a0e60e8a2647b15ab Mon Sep 17 00:00:00 2001
From: siderakis <nixsid@gmail.com>
Date: Wed, 21 Mar 2018 01:03:54 -0400
Subject: [PATCH] Use dataload when fetching all the books for a shelf

---
 .../library/graphqlserver/GraphQlServer.java   | 13 +++++++------
 .../graphqlserver/LibrarySchemaModule.java     | 18 ++++++------------
 2 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/examples/src/main/java/com/google/api/graphql/examples/library/graphqlserver/GraphQlServer.java b/examples/src/main/java/com/google/api/graphql/examples/library/graphqlserver/GraphQlServer.java
index 8c08b07..633b886 100644
--- a/examples/src/main/java/com/google/api/graphql/examples/library/graphqlserver/GraphQlServer.java
+++ b/examples/src/main/java/com/google/api/graphql/examples/library/graphqlserver/GraphQlServer.java
@@ -29,6 +29,10 @@
 import java.util.EnumSet;
 import java.util.logging.Logger;
 
+import static javax.servlet.DispatcherType.ASYNC;
+import static javax.servlet.DispatcherType.REQUEST;
+import static org.eclipse.jetty.servlet.ServletContextHandler.SESSIONS;
+
 public class GraphQlServer {
 
   private static final int HTTP_PORT = 8080;
@@ -38,7 +42,7 @@ public static void main(String[] args) throws Exception {
     Server server = new Server(HTTP_PORT);
 
     ServletContextHandler context =
-        new ServletContextHandler(server, "/", ServletContextHandler.SESSIONS);
+        new ServletContextHandler(server, "/", SESSIONS);
 
     context.addEventListener(
         new GuiceServletContextListener() {
@@ -53,7 +57,7 @@ protected void configureServlets() {
                 },
                 new DataLoaderModule(),
                 new SchemaProviderModule(), // Part of Rejoiner framework (Provides `@Schema
-                                            // GraphQLSchema`)
+                // GraphQLSchema`)
                 new BookClientModule(), // Configures the Book gRPC client
                 new ShelfClientModule(), // Configures the Shelf gRPC client
                 new BookSchemaModule(), // Creates queries and mutations for the Book service
@@ -64,10 +68,7 @@ protected void configureServlets() {
           }
         });
 
-    context.addFilter(
-        GuiceFilter.class,
-        "/*",
-        EnumSet.of(javax.servlet.DispatcherType.REQUEST, javax.servlet.DispatcherType.ASYNC));
+    context.addFilter(GuiceFilter.class, "/*", EnumSet.of(REQUEST, ASYNC));
 
     context.setBaseResource(
         new PathResource(new File("./src/main/resources").toPath().toRealPath()));
diff --git a/examples/src/main/java/com/google/api/graphql/examples/library/graphqlserver/LibrarySchemaModule.java b/examples/src/main/java/com/google/api/graphql/examples/library/graphqlserver/LibrarySchemaModule.java
index bad9350..73beaad 100644
--- a/examples/src/main/java/com/google/api/graphql/examples/library/graphqlserver/LibrarySchemaModule.java
+++ b/examples/src/main/java/com/google/api/graphql/examples/library/graphqlserver/LibrarySchemaModule.java
@@ -18,16 +18,16 @@
 import com.google.api.graphql.rejoiner.Mutation;
 import com.google.api.graphql.rejoiner.SchemaModification;
 import com.google.api.graphql.rejoiner.SchemaModule;
-import com.google.common.collect.ImmutableList;
-import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.example.library.book.v1.Book;
 import com.google.example.library.book.v1.BookServiceGrpc;
 import com.google.example.library.book.v1.CreateBookRequest;
-import com.google.example.library.book.v1.GetBookRequest;
 import com.google.example.library.shelf.v1.GetShelfRequest;
 import com.google.example.library.shelf.v1.Shelf;
 import com.google.example.library.shelf.v1.ShelfServiceGrpc;
+import net.javacrumbs.futureconverter.java8guava.FutureConverter;
+import org.dataloader.DataLoaderRegistry;
+
 import java.util.List;
 
 /** A GraphQL {@link SchemaModule} backed by a gRPC service. */
@@ -47,14 +47,8 @@ Book createBookAndAddToShelf(
   }
 
   @SchemaModification(addField = "books", onType = Shelf.class)
-  ListenableFuture<List<Book>> shelfToBooks(
-      Shelf shelf, BookServiceGrpc.BookServiceFutureStub bookClient) {
-    // TODO: use a data loader or batch endpoint
-    return Futures.allAsList(
-        shelf
-            .getBookIdsList()
-            .stream()
-            .map(id -> bookClient.getBook(GetBookRequest.newBuilder().setId(id).build()))
-            .collect(ImmutableList.toImmutableList()));
+  ListenableFuture<List<Book>> shelfToBooks(Shelf shelf, DataLoaderRegistry dataLoaderRegistry) {
+    return FutureConverter.toListenableFuture(
+        dataLoaderRegistry.<String, Book>getDataLoader("books").loadMany(shelf.getBookIdsList()));
   }
 }