Adding additional configuration for Connections to fetch data asynchronously

Author: vinayknl

src/main/java/graphql/annotations/connection/GraphQLConnection.java

@@ -52,4 +52,11 @@
      * @return a connection validator
      */
     Class <? extends ConnectionValidator> validator() default PaginatedDataConnectionTypeValidator.class;
+
+    /**
+     * By default, the paginated data is fetched synchronously. If explicitly specified, asynchronous data fetching
+     * will be used.
+     * @return if async fetching to be used.
+     */
+    boolean async() default false;
 }

src/main/java/graphql/annotations/dataFetchers/connection/AsyncConnectionDataFetcher.java

@@ -0,0 +1,36 @@
+/**
+ * Copyright 2016 Yurii Rashkovskii
+ *
+ * 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
+ *
+ *     http://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
+ */
+package graphql.annotations.dataFetchers.connection;
+
+import graphql.schema.DataFetcher;
+import graphql.schema.DataFetchingEnvironment;
+
+import java.util.concurrent.CompletableFuture;
+
+import static java.util.concurrent.CompletableFuture.supplyAsync;
+
+public class AsyncConnectionDataFetcher<T> implements DataFetcher<CompletableFuture<graphql.relay.Connection<T>>> {
+    private final ConnectionDataFetcher connectionDataFetcher;
+
+    @SuppressWarnings("unchecked")
+    public AsyncConnectionDataFetcher(ConnectionDataFetcher connectionFetcher) {
+        this.connectionDataFetcher = connectionFetcher;
+    }
+
+    @Override
+    public CompletableFuture<graphql.relay.Connection<T>> get(DataFetchingEnvironment environment) {
+        return supplyAsync(() -> connectionDataFetcher.get(environment));
+    }
+}

src/main/java/graphql/annotations/dataFetchers/connection/ConnectionDataFetcher.java

@@ -21,12 +21,10 @@
 import java.lang.reflect.Constructor;
 import java.util.Arrays;
 import java.util.Optional;
-import java.util.concurrent.CompletableFuture;
 
 import static graphql.annotations.processor.util.ReflectionKit.constructNewInstance;
-import static java.util.concurrent.CompletableFuture.supplyAsync;
 
-public class ConnectionDataFetcher<T> implements DataFetcher<CompletableFuture<graphql.relay.Connection<T>>> {
+public class ConnectionDataFetcher<T> implements DataFetcher<graphql.relay.Connection<T>> {
     private final DataFetcher<?> actualDataFetcher;
     private final Constructor<ConnectionFetcher<T>> constructor;
 
@@ -46,8 +44,8 @@ public ConnectionDataFetcher(Class<? extends ConnectionFetcher<T>> connection, D
     }
 
     @Override
-    public CompletableFuture<graphql.relay.Connection<T>> get(DataFetchingEnvironment environment) {
+    public graphql.relay.Connection<T> get(DataFetchingEnvironment environment) {
         ConnectionFetcher<T> conn = constructNewInstance(constructor, actualDataFetcher);
-        return supplyAsync(() -> conn.get(environment));
+        return conn.get(environment);
     }
 }

src/main/java/graphql/annotations/processor/retrievers/fieldBuilders/field/FieldDataFetcherBuilder.java

@@ -19,17 +19,20 @@
 import graphql.annotations.connection.GraphQLConnection;
 import graphql.annotations.dataFetchers.ExtensionDataFetcherWrapper;
 import graphql.annotations.dataFetchers.MethodDataFetcher;
-import graphql.annotations.dataFetchers.connection.ConnectionDataFetcher;
 import graphql.annotations.processor.ProcessingElementsContainer;
 import graphql.annotations.processor.retrievers.fieldBuilders.Builder;
 import graphql.annotations.processor.typeFunctions.TypeFunction;
 import graphql.annotations.processor.util.DataFetcherConstructor;
-import graphql.schema.*;
+import graphql.schema.DataFetcher;
+import graphql.schema.GraphQLNonNull;
+import graphql.schema.GraphQLType;
+import graphql.schema.PropertyDataFetcher;
 
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 
 import static graphql.Scalars.GraphQLBoolean;
+import static graphql.annotations.processor.util.ConnectionUtil.getConnectionDataFetcher;
 import static java.util.Objects.nonNull;
 
 public class FieldDataFetcherBuilder implements Builder<DataFetcher> {
@@ -61,9 +64,8 @@ public DataFetcher build() {
             actualDataFetcher = handleNullCase(actualDataFetcher);
         }
 
-
         if (isConnection) {
-            actualDataFetcher = new ConnectionDataFetcher(field.getAnnotation(GraphQLConnection.class).connection(), actualDataFetcher);
+            actualDataFetcher = getConnectionDataFetcher(field.getAnnotation(GraphQLConnection.class), actualDataFetcher);
         }
         return actualDataFetcher;
     }
@@ -75,7 +77,7 @@ private DataFetcher handleNullCase(DataFetcher actualDataFetcher) {
             actualDataFetcher = getBooleanDataFetcher(actualDataFetcher);
         } else if (checkIfPrefixGetterExists(field.getDeclaringClass(), "get", field.getName())) {
             actualDataFetcher = wrapExtension(new PropertyDataFetcher(field.getName()), field);
-        } else{
+        } else {
             actualDataFetcher = getDataFetcherWithFluentGetter(actualDataFetcher);
         }
 

src/main/java/graphql/annotations/processor/retrievers/fieldBuilders/method/MethodDataFetcherBuilder.java

@@ -21,7 +21,6 @@
 import graphql.annotations.dataFetchers.BatchedMethodDataFetcher;
 import graphql.annotations.dataFetchers.MethodDataFetcher;
 import graphql.annotations.dataFetchers.RelayMutationMethodDataFetcher;
-import graphql.annotations.dataFetchers.connection.ConnectionDataFetcher;
 import graphql.annotations.processor.ProcessingElementsContainer;
 import graphql.annotations.processor.retrievers.fieldBuilders.Builder;
 import graphql.annotations.processor.typeFunctions.TypeFunction;
@@ -34,6 +33,8 @@
 import java.lang.reflect.Method;
 import java.util.List;
 
+import static graphql.annotations.processor.util.ConnectionUtil.getConnectionDataFetcher;
+
 public class MethodDataFetcherBuilder implements Builder<DataFetcher> {
     private Method method;
     private GraphQLOutputType outputType;
@@ -74,7 +75,7 @@ public DataFetcher build() {
         }
 
         if (isConnection){
-            actualDataFetcher = new ConnectionDataFetcher(method.getAnnotation(GraphQLConnection.class).connection(), actualDataFetcher);
+            actualDataFetcher = getConnectionDataFetcher(method.getAnnotation(GraphQLConnection.class), actualDataFetcher);
         }
         return actualDataFetcher;
     }

src/main/java/graphql/annotations/processor/util/ConnectionUtil.java

@@ -16,6 +16,8 @@
 
 import graphql.annotations.connection.ConnectionValidator;
 import graphql.annotations.connection.GraphQLConnection;
+import graphql.annotations.dataFetchers.connection.AsyncConnectionDataFetcher;
+import graphql.annotations.dataFetchers.connection.ConnectionDataFetcher;
 import graphql.schema.*;
 
 import java.lang.reflect.AccessibleObject;
@@ -45,4 +47,12 @@ public static boolean isConnection(AccessibleObject obj, GraphQLType type) {
         }
     }
 
+    public static DataFetcher getConnectionDataFetcher(GraphQLConnection connectionAnnotation, DataFetcher actualDataFetcher) {
+        actualDataFetcher = new ConnectionDataFetcher(connectionAnnotation.connection(), actualDataFetcher);
+        if (connectionAnnotation.async()) {
+            actualDataFetcher = new AsyncConnectionDataFetcher((ConnectionDataFetcher) actualDataFetcher);
+        }
+        return actualDataFetcher;
+    }
+
 }