PropertySelection nests within Connection/edges/node

Closes gh-723

Author: rstoyanchev

spring-graphql/src/main/java/org/springframework/graphql/data/query/PropertySelection.java

@@ -23,6 +23,7 @@
 import java.util.function.Function;
 
 import graphql.schema.DataFetchingFieldSelectionSet;
+import graphql.schema.GraphQLNamedOutputType;
 import graphql.schema.SelectedField;
 
 import org.springframework.data.mapping.PropertyPath;
@@ -83,6 +84,12 @@ private static List<PropertyPath> getPropertyPaths(
 			String propertyName = selectedField.getName();
 			TypeInformation<?> propertyTypeInfo = typeInfo.getProperty(propertyName);
 			if (propertyTypeInfo == null) {
+				if (isConnectionEdges(selectedField)) {
+					getConnectionPropertyPaths(typeInfo, selection, pathFactory, selectedField, result);
+				}
+				else if (isConnectionEdgeNode(selectedField)) {
+					getConnectionPropertyPaths(typeInfo, selection, pathFactory, selectedField, result);
+				}
 				continue;
 			}
 
@@ -102,6 +109,30 @@ private static List<PropertyPath> getPropertyPaths(
 		return result;
 	}
 
+	private static boolean isConnectionEdges(SelectedField selectedField) {
+		return selectedField.getName().equals("edges") &&
+			   selectedField.getParentField().getType() instanceof GraphQLNamedOutputType namedType &&
+			   namedType.getName().endsWith("Connection");
+	}
+
+	private static boolean isConnectionEdgeNode(SelectedField selectedField) {
+		return selectedField.getName().equals("node") && isConnectionEdges(selectedField.getParentField());
+	}
+
+	private static void getConnectionPropertyPaths(
+			TypeInformation<?> typeInfo, FieldSelection selection, Function<String, PropertyPath> pathFactory,
+			SelectedField selectedField, List<PropertyPath> result) {
+
+		FieldSelection nestedSelection = selection.select(selectedField);
+		if (!nestedSelection.isEmpty()) {
+			TypeInformation<?> actualType = typeInfo.getRequiredActualType();
+			List<PropertyPath> paths = getPropertyPaths(actualType, nestedSelection, pathFactory);
+			if (!CollectionUtils.isEmpty(paths)) {
+				result.addAll(paths);
+			}
+		}
+	}
+
 
 	/**
 	 * Hierarchical representation of selected fields. Allows traversing the

spring-graphql/src/test/java/org/springframework/graphql/data/query/PropertySelectionTests.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * 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 org.springframework.graphql.data.query;
+
+import java.util.List;
+import java.util.concurrent.atomic.AtomicReference;
+
+import graphql.schema.DataFetcher;
+import graphql.schema.DataFetchingFieldSelectionSet;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.data.util.TypeInformation;
+import org.springframework.graphql.BookSource;
+import org.springframework.graphql.GraphQlSetup;
+import org.springframework.graphql.execution.ConnectionTypeDefinitionConfigurer;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit test for {@link PropertySelection}.
+ *
+ * @author Rossen Stoyanchev
+ */
+public class PropertySelectionTests {
+
+	@Test
+	void propertySelectionWithConnection() {
+
+		AtomicReference<DataFetchingFieldSelectionSet> ref = new AtomicReference<>();
+		DataFetcher<?> dataFetcher = environment -> {
+			ref.set(environment.getSelectionSet());
+			return null;
+		};
+
+		GraphQlSetup.schemaResource(BookSource.paginationSchema)
+				.typeDefinitionConfigurer(new ConnectionTypeDefinitionConfigurer())
+				.dataFetcher("Query", "books", dataFetcher)
+				.toGraphQlService()
+				.execute(BookSource.booksConnectionQuery(""))
+				.block();
+
+		TypeInformation<Book> typeInfo = TypeInformation.of(Book.class);
+
+		List<String> list = PropertySelection.create(typeInfo, ref.get()).toList();
+		assertThat(list).containsExactly("id", "name");
+	}
+
+}