Support for pagination

ConnectionTypeVisitor to decorate DataFetchers for Connection fields
in order to adapt Window, Slice, and others to Connection.

A ScrollRequest controller method argument to inject the ScrollPosition
and the number of elements requested.

SortStrategy for an application to customize how to extract sort
details from GraphQL arguments.

See gh-620

Author: rstoyanchev

platform/build.gradle

@@ -12,7 +12,7 @@ dependencies {
 	api(platform("io.projectreactor:reactor-bom:2022.0.3"))
 	api(platform("io.micrometer:micrometer-bom:1.10.4"))
 	api(platform("io.micrometer:micrometer-tracing-bom:1.0.2"))
-	api(platform("org.springframework.data:spring-data-bom:2022.0.2"))
+	api(platform("org.springframework.data:spring-data-bom:2023.0.0-SNAPSHOT"))
 	api(platform("org.springframework.security:spring-security-bom:6.0.1"))
 	api(platform("com.querydsl:querydsl-bom:5.0.0"))
 	api(platform("io.rsocket:rsocket-bom:1.1.3"))

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/AnnotatedControllerConfigurer.java

@@ -67,6 +67,8 @@
 import org.springframework.graphql.data.method.HandlerMethodArgumentResolverComposite;
 import org.springframework.graphql.data.method.annotation.BatchMapping;
 import org.springframework.graphql.data.method.annotation.SchemaMapping;
+import org.springframework.graphql.data.pagination.CursorStrategy;
+import org.springframework.graphql.data.pagination.SortStrategy;
 import org.springframework.graphql.execution.BatchLoaderRegistry;
 import org.springframework.graphql.execution.DataFetcherExceptionResolver;
 import org.springframework.graphql.execution.RuntimeWiringConfigurer;
@@ -124,6 +126,12 @@ public class AnnotatedControllerConfigurer
 
 	private final FormattingConversionService conversionService = new DefaultFormattingConversionService();
 
+	@Nullable
+	private CursorStrategy<?> cursorStrategy;
+
+	@Nullable
+	private SortStrategy<?> sortStrategy;
+
 	private final List<HandlerMethodArgumentResolver> customArgumentResolvers = new ArrayList<>(8);
 
 	@Nullable
@@ -152,6 +160,32 @@ public void addFormatterRegistrar(FormatterRegistrar registrar) {
 		registrar.registerFormatters(this.conversionService);
 	}
 
+	/**
+	 * Configure a {@link CursorStrategy} to handle pagination requests, which
+	 * results in one of the following:
+	 * <ul>
+	 * <li>If Spring Data is present, and the strategy supports {@code ScrollPosition},
+	 * then {@link ScrollRequestMethodArgumentResolver} is
+	 * configured as a method argument resolver.
+	 * <li>Otherwise {@link PaginationRequestMethodArgumentResolver} is added
+	 * instead.
+	 * </ul>
+	 * @since 1.2
+	 */
+	public void setCursorStrategy(@Nullable CursorStrategy<?> cursorStrategy) {
+		this.cursorStrategy = cursorStrategy;
+	}
+
+	/**
+	 * Configure a {@link SortStrategy} to extract sort details for pagination
+	 * requests. This results in {@link SortMethodArgumentResolver} being added
+	 * as a method argument resolver.
+	 * @since 1.2
+	 */
+	public void setSortStrategy(SortStrategy<?> sortStrategy) {
+		this.sortStrategy = sortStrategy;
+	}
+
 	/**
 	 * Add a {@link HandlerMethodArgumentResolver} for custom controller method
 	 * arguments. Such custom resolvers are ordered after built-in resolvers
@@ -251,6 +285,12 @@ private HandlerMethodArgumentResolverComposite initArgumentResolvers() {
 		// Type based
 		resolvers.addResolver(new DataFetchingEnvironmentMethodArgumentResolver());
 		resolvers.addResolver(new DataLoaderMethodArgumentResolver());
+		if (this.cursorStrategy != null) {
+			resolvers.addResolver(initPaginationResolver(this.cursorStrategy));
+		}
+		if (this.sortStrategy != null) {
+			resolvers.addResolver(new SortMethodArgumentResolver(this.sortStrategy));
+		}
 		if (springSecurityPresent) {
 			resolvers.addResolver(new PrincipalMethodArgumentResolver());
 			BeanResolver beanResolver = new BeanFactoryResolver(obtainApplicationContext());
@@ -268,6 +308,17 @@ private HandlerMethodArgumentResolverComposite initArgumentResolvers() {
 		return resolvers;
 	}
 
+	@SuppressWarnings("unchecked")
+	private HandlerMethodArgumentResolver initPaginationResolver(CursorStrategy<?> cursorStrategy) {
+		if (springDataPresent) {
+			if (cursorStrategy.supports(org.springframework.data.domain.ScrollPosition.class)) {
+				return new ScrollRequestMethodArgumentResolver(
+						(CursorStrategy<org.springframework.data.domain.ScrollPosition>) cursorStrategy);
+			}
+		}
+		return new PaginationRequestMethodArgumentResolver<>(cursorStrategy);
+	}
+
 	protected final ApplicationContext obtainApplicationContext() {
 		Assert.state(this.applicationContext != null, "No ApplicationContext");
 		return this.applicationContext;

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/PaginationRequestMethodArgumentResolver.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2020-2023 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.method.annotation.support;
+
+
+import graphql.schema.DataFetchingEnvironment;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.graphql.data.method.HandlerMethodArgumentResolver;
+import org.springframework.graphql.data.pagination.CursorStrategy;
+import org.springframework.graphql.data.pagination.PaginationRequest;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+
+/**
+ * Resolver for a method argument of type {@link PaginationRequest} initialized
+ * from "first", "last", "before", and "after" GraphQL arguments.
+ *
+ * @author Rossen Stoyanchev
+ * @since 1.2
+ */
+public class PaginationRequestMethodArgumentResolver<P> implements HandlerMethodArgumentResolver {
+
+	private final CursorStrategy<P> cursorStrategy;
+
+
+	public PaginationRequestMethodArgumentResolver(CursorStrategy<P> cursorStrategy) {
+		Assert.notNull(cursorStrategy, "CursorStrategy is required");
+		this.cursorStrategy = cursorStrategy;
+	}
+
+
+	@Override
+	public boolean supportsParameter(MethodParameter parameter) {
+		return (parameter.getParameterType().equals(PaginationRequest.class) &&
+				this.cursorStrategy.supports(parameter.nested().getNestedParameterType()));
+	}
+
+	@Override
+	public Object resolveArgument(MethodParameter parameter, DataFetchingEnvironment environment) throws Exception {
+		boolean forward = !environment.getArguments().containsKey("last");
+		String cursor = environment.getArgument(forward ? "before" : "after");
+		Integer count = environment.getArgument(forward ? "first" : "last");
+		P position = (cursor != null ? this.cursorStrategy.fromCursor(cursor) : null);
+		return createRequest(position, count, forward);
+	}
+
+	/**
+	 * Create the {@code PaginationRequest} instance.
+	 */
+	protected PaginationRequest<P> createRequest(@Nullable P position, @Nullable Integer size, boolean forward) {
+		return new PaginationRequest<>(position, size, forward);
+	}
+
+}

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/ScrollRequestMethodArgumentResolver.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2020-2023 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.method.annotation.support;
+
+
+import org.springframework.core.MethodParameter;
+import org.springframework.data.domain.ScrollPosition;
+import org.springframework.graphql.data.pagination.CursorStrategy;
+import org.springframework.graphql.data.query.ScrollRequest;
+import org.springframework.lang.Nullable;
+
+
+/**
+ * Subclass of {@link PaginationRequestMethodArgumentResolver} that supports
+ * {@link ScrollRequest} with cursors converted to {@link ScrollPosition} for
+ * forward or backward pagination.
+ *
+ * @author Rossen Stoyanchev
+ * @since 1.2
+ */
+public class ScrollRequestMethodArgumentResolver extends PaginationRequestMethodArgumentResolver<ScrollPosition> {
+
+
+	public ScrollRequestMethodArgumentResolver(CursorStrategy<ScrollPosition> cursorStrategy) {
+		super(cursorStrategy);
+	}
+
+
+	@Override
+	public boolean supportsParameter(MethodParameter parameter) {
+		return parameter.getParameterType().equals(ScrollRequest.class);
+	}
+
+	protected ScrollRequest createRequest(@Nullable ScrollPosition position, @Nullable Integer size, boolean forward) {
+		return new ScrollRequest(position, size, forward);
+	}
+
+}

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/SortMethodArgumentResolver.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2020-2023 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.method.annotation.support;
+
+
+import graphql.schema.DataFetchingEnvironment;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.graphql.data.method.HandlerMethodArgumentResolver;
+import org.springframework.graphql.data.pagination.SortStrategy;
+import org.springframework.util.Assert;
+
+
+/**
+ * Resolver for a Sort object decoded with {@link SortStrategy}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 1.2
+ */
+public class SortMethodArgumentResolver implements HandlerMethodArgumentResolver {
+
+	private final SortStrategy<?> sortStrategy;
+
+
+	public SortMethodArgumentResolver(SortStrategy<?> sortStrategy) {
+		Assert.notNull(sortStrategy, "SortStrategy is required");
+		this.sortStrategy = sortStrategy;
+	}
+
+
+	@Override
+	public boolean supportsParameter(MethodParameter parameter) {
+		return this.sortStrategy.supports(parameter.getParameterType());
+	}
+
+	@Override
+	public Object resolveArgument(MethodParameter parameter, DataFetchingEnvironment environment) {
+		return this.sortStrategy.extract(environment);
+	}
+
+}

spring-graphql/src/main/java/org/springframework/graphql/data/pagination/Base64CursorEncoder.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2020-2023 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.pagination;
+
+
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
+
+
+/**
+ * {@link CursorEncoder} that applies Base 64 encoding and decoding.
+ *
+ * @author Rossen Stoyanchev
+ * @since 1.2
+ */
+final class Base64CursorEncoder implements CursorEncoder {
+
+	private final Charset charset = StandardCharsets.UTF_8;
+
+
+	@Override
+	public String encode(String cursor) {
+		byte[] bytes = Base64.getEncoder().encode(cursor.getBytes(this.charset));
+		return new String(bytes, this.charset);
+	}
+
+	@Override
+	public String decode(String cursor) {
+		byte[] bytes = Base64.getDecoder().decode(cursor.getBytes(this.charset));
+		return new String(bytes, this.charset);
+	}
+
+}