[4233] Add Cursor-based pagination in Project related GET REST APIs

Bug: #4233
Signed-off-by: Axel RICHARD <axel.richard@obeo.fr>

CHANGELOG.adoc

@@ -54,6 +54,22 @@ A new `IProjectDataVersioningRestServiceDelegate` interface is available, allowi
 Specifiers can implement this new interface with a spring `Service`.
 A new `IRestDataVersionPayloadSerializerService` interface is available, allowing to customize the default implementation of the JSON serialization of the payload object of `RestDataVersion`.
 Specifiers are also encouraged to implement their own `IRestDataVersionPayloadSerializerService` for their domains, as the default one may not return expected results.
+- https://github.com/eclipse-sirius/sirius-web/issues/4233[#4233] [core] Add cursor-based pagination for Project related GET REST APIs.
+New optional attributes are available on all Project related GET REST APIs returning a list of objects, allowing to paginate the data returned by those APIs.
+The following APIs are concerned:
+** getProjects (`GET /api/rest/projects`)
+The new optional attributes are:
+** `page[size]` specifies the maximum number of records that will be returned per page in the response
+** `page[before]` specifies the URL of the page succeeding the page being requested
+** `page[after]` specifies the URL of a page preceding the page being requested
+If neither `page[before]` nor `page[after]` is specified, the first page is returned with the same number of records as specified in the `page[size]` query parameter.
+If the `page[size]` parameter is not specified, then the default page size is used, which is 20.
+Example:
+ ** `http://my-sirius-web-server:8080/api/rest/projects?
+page[after]=MTYxODg2MTQ5NjYzMnwyMDEwOWY0MC00ODI1LTQxNmEtODZmNi03NTA4YWM0MmEwMjE&
+page[size]=3` will ask for the 3 projects following the one identified by the URL of the page succeeding the page being requested `MTYxODg2MTQ5NjYzMnwyMDEwOWY0MC00ODI1LTQxNmEtODZmNi03NTA4YWM0MmEwMjE`.
+Note that you can retrieve the URL of a page in the response header of `GET /api/rest/projects`.
+Note that you may need to encode special characters like `[`(by `%5B`) and `]` (by `%5D`) in your requests.
 
 === Improvements
 

packages/sirius-web/backend/sirius-web-application/src/main/java/org/eclipse/sirius/web/application/project/controllers/ProjectRestController.java

@@ -16,6 +16,7 @@
 import java.time.OffsetDateTime;
 import java.time.ZoneOffset;
 import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.UUID;
@@ -30,9 +31,12 @@
 import org.eclipse.sirius.web.application.project.dto.RenameProjectSuccessPayload;
 import org.eclipse.sirius.web.application.project.dto.RestProject;
 import org.eclipse.sirius.web.application.project.services.api.IProjectApplicationService;
-import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.KeysetScrollPosition;
+import org.springframework.data.domain.ScrollPosition;
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.util.MultiValueMap;
 import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
@@ -41,6 +45,10 @@
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
+import org.springframework.web.util.UriComponents;
+
+import graphql.relay.Relay;
 
 /**
  * REST Controller for the Project Endpoint.
@@ -51,6 +59,8 @@
 @RequestMapping("/api/rest/projects")
 public class ProjectRestController {
 
+    private static final int DEFAULT_PAGE_SIZE = 20;
+
     private static final OffsetDateTime DEFAULT_CREATED = Instant.EPOCH.atOffset(ZoneOffset.UTC);
 
     private final IProjectApplicationService projectApplicationService;
@@ -60,12 +70,26 @@ public ProjectRestController(IProjectApplicationService projectApplicationServic
     }
 
     @GetMapping
-    public ResponseEntity<List<RestProject>> getProjects() {
-        var restProjects = this.projectApplicationService.findAll(PageRequest.of(0, 20))
+    public ResponseEntity<List<RestProject>> getProjects(@RequestParam(name = "page[size]") Optional<Integer> pageSize, @RequestParam(name = "page[after]") Optional<String> pageAfter, @RequestParam(name = "page[before]") Optional<String> pageBefore) {
+        final KeysetScrollPosition position;
+        if (pageAfter.isPresent() && pageBefore.isEmpty()) {
+            var cursorProjectId = new Relay().fromGlobalId(pageAfter.get()).getId();
+            position = ScrollPosition.forward(Map.of("id", cursorProjectId));
+        } else if (pageBefore.isPresent() && pageAfter.isEmpty()) {
+            var cursorProjectId = new Relay().fromGlobalId(pageBefore.get()).getId();
+            position = ScrollPosition.backward(Map.of("id", cursorProjectId));
+        } else if (pageBefore.isPresent() && pageAfter.isPresent()) {
+            position = ScrollPosition.keyset();
+        } else {
+            position = ScrollPosition.keyset();
+        }
+        int limit = pageSize.orElse(DEFAULT_PAGE_SIZE);
+        var window = this.projectApplicationService.findAll(position, limit);
+        var restProjects = window
             .map(project -> new RestProject(project.id(), DEFAULT_CREATED, new Identified(project.id()), null, project.name()))
             .toList();
-
-        return new ResponseEntity<>(restProjects, HttpStatus.OK);
+        var headers = this.handleLinkResponseHeader(restProjects, position, window.hasNext(), limit);
+        return new ResponseEntity<>(restProjects, headers, HttpStatus.OK);
     }
 
     @GetMapping(path = "/{projectId}")
@@ -123,4 +147,33 @@ public ResponseEntity<RestProject> deleteProject(@PathVariable UUID projectId) {
 
         return new ResponseEntity<>(restProject, HttpStatus.OK);
     }
+
+    private MultiValueMap<String, String> handleLinkResponseHeader(List<RestProject> projects, KeysetScrollPosition position, boolean hasNext, int limit) {
+        MultiValueMap<String, String> headers = new HttpHeaders();
+        int projectsSize = projects.size();
+        if (projectsSize > 0 && position.scrollsForward() && hasNext) {
+            var headerLink = this.createHeaderLink(projects, limit, "after", "next");
+            headers.add(HttpHeaders.LINK, headerLink);
+        } else if (projectsSize > 0 && position.scrollsBackward() && hasNext) {
+            var headerLink = this.createHeaderLink(projects, limit, "before", "prev");
+            headers.add(HttpHeaders.LINK, headerLink);
+        }
+        return headers;
+    }
+
+    private String createHeaderLink(List<RestProject> projects, int limit, String beforeOrAfterPage, String relationType) {
+        var header = new StringBuilder();
+        var lastProject = projects.get(Math.min(projects.size() - 1, limit - 1));
+        var cursorId = new Relay().toGlobalId("Project", lastProject.id().toString());
+        UriComponents uriComponents = ServletUriComponentsBuilder.fromCurrentRequestUri()
+                .queryParam("page[" + beforeOrAfterPage + "]", cursorId)
+                .queryParam("page[size]", limit)
+                .build();
+        header.append("<");
+        header.append(uriComponents.toUriString());
+        header.append(">; rel=\"");
+        header.append(relationType);
+        header.append("\"");
+        return header.toString();
+    }
 }

packages/sirius-web/backend/sirius-web-application/src/main/java/org/eclipse/sirius/web/application/project/controllers/ViewerProjectsDataFetcher.java

@@ -12,6 +12,7 @@
  *******************************************************************************/
 package org.eclipse.sirius.web.application.project.controllers;
 
+import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 
@@ -20,8 +21,9 @@
 import org.eclipse.sirius.components.graphql.api.IDataFetcherWithFieldCoordinates;
 import org.eclipse.sirius.web.application.project.dto.ProjectDTO;
 import org.eclipse.sirius.web.application.project.services.api.IProjectApplicationService;
-import org.springframework.data.domain.Page;
-import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.KeysetScrollPosition;
+import org.springframework.data.domain.ScrollPosition;
+import org.springframework.data.domain.Window;
 
 import graphql.relay.Connection;
 import graphql.relay.ConnectionCursor;
@@ -40,9 +42,15 @@
 @QueryDataFetcher(type = "Viewer", field = "projects")
 public class ViewerProjectsDataFetcher implements IDataFetcherWithFieldCoordinates<Connection<ProjectDTO>> {
 
-    private static final String PAGE_ARGUMENT = "page";
+    private static final int DEFAULT_PAGE_SIZE = 20;
 
-    private static final String LIMIT_ARGUMENT = "limit";
+    private static final String FIRST_ARGUMENT = "first";
+
+    private static final String LAST_ARGUMENT = "last";
+
+    private static final String AFTER_ARGUMENT = "after";
+
+    private static final String BEFORE_ARGUMENT = "before";
 
     private final IProjectApplicationService projectApplicationService;
 
@@ -52,19 +60,56 @@ public ViewerProjectsDataFetcher(IProjectApplicationService projectApplicationSe
 
     @Override
     public Connection<ProjectDTO> get(DataFetchingEnvironment environment) throws Exception {
-        int page = Optional.<Integer> ofNullable(environment.getArgument(PAGE_ARGUMENT))
-                .filter(pageArgument -> pageArgument > 0)
-                .orElse(0);
-        int limit = Optional.<Integer> ofNullable(environment.getArgument(LIMIT_ARGUMENT))
-                .filter(limitArgument -> limitArgument > 0)
-                .orElse(20);
-
-        var pageable = PageRequest.of(page, limit);
-        var projectPage = this.projectApplicationService.findAll(pageable);
-        return this.toConnection(projectPage);
+        Optional<Integer> first = Optional.<Integer> ofNullable(environment.getArgument(FIRST_ARGUMENT));
+        Optional<Integer> last = Optional.<Integer> ofNullable(environment.getArgument(LAST_ARGUMENT));
+        Optional<String> after = Optional.<String> ofNullable(environment.getArgument(AFTER_ARGUMENT));
+        Optional<String> before = Optional.<String> ofNullable(environment.getArgument(BEFORE_ARGUMENT));
+
+        final KeysetScrollPosition position;
+        final int limit;
+        if (after.isPresent() && before.isEmpty()) {
+            var projectId = after.get();
+            var cursorProjectId = new Relay().fromGlobalId(projectId).getId();
+            position = ScrollPosition.forward(Map.of("id", cursorProjectId));
+            if (last.isPresent()) {
+                limit = 0;
+            } else if (first.isPresent()) {
+                limit = first.get();
+            } else {
+                limit = DEFAULT_PAGE_SIZE;
+            }
+        } else if (before.isPresent() && after.isEmpty()) {
+            var projectId = before.get();
+            var cursorProjectId = new Relay().fromGlobalId(projectId).getId();
+            position = ScrollPosition.backward(Map.of("id", cursorProjectId));
+            if (first.isPresent()) {
+                limit = 0;
+            } else if (last.isPresent()) {
+                limit = last.get();
+            } else {
+                limit = DEFAULT_PAGE_SIZE;
+            }
+        } else if (before.isPresent() && after.isPresent()) {
+            position = ScrollPosition.keyset();
+            limit = 0;
+        } else {
+            position = ScrollPosition.keyset();
+            if (first.isPresent() && last.isPresent()) {
+                limit = 0;
+            } else if (first.isPresent()) {
+                limit = first.get();
+            } else if (last.isPresent()) {
+                limit = last.get();
+            } else {
+                limit = DEFAULT_PAGE_SIZE;
+            }
+        }
+
+        var projectPage = this.projectApplicationService.findAll(position, limit);
+        return this.toConnection(projectPage, position);
     }
 
-    private Connection<ProjectDTO> toConnection(Page<ProjectDTO> projectPage) {
+    private Connection<ProjectDTO> toConnection(Window<ProjectDTO> projectPage, KeysetScrollPosition position) {
         var edges = projectPage.stream().map(projectDTO -> {
             var globalId = new Relay().toGlobalId("Project", projectDTO.id().toString());
             var cursor = new DefaultConnectionCursor(globalId);
@@ -78,7 +123,15 @@ private Connection<ProjectDTO> toConnection(Page<ProjectDTO> projectPage) {
         if (!edges.isEmpty()) {
             endCursor = edges.get(edges.size() - 1).getCursor();
         }
-        var pageInfo = new PageInfoWithCount(startCursor, endCursor, projectPage.hasPrevious(), projectPage.hasNext(), projectPage.getTotalElements());
+        boolean hasPreviousPage = false;
+        if (position.scrollsBackward()) {
+            hasPreviousPage = projectPage.hasNext();
+        }
+        boolean hasNextPage = false;
+        if (position.scrollsForward()) {
+            hasNextPage = projectPage.hasNext();
+        }
+        var pageInfo = new PageInfoWithCount(startCursor, endCursor, hasPreviousPage, hasNextPage, projectPage.size());
         return new DefaultConnection<>(edges, pageInfo);
     }
 }

packages/sirius-web/backend/sirius-web-application/src/main/java/org/eclipse/sirius/web/application/project/services/ProjectApplicationService.java

@@ -34,8 +34,8 @@
 import org.eclipse.sirius.web.domain.boundedcontexts.project.services.api.IProjectUpdateService;
 import org.eclipse.sirius.web.domain.services.Failure;
 import org.eclipse.sirius.web.domain.services.Success;
-import org.springframework.data.domain.Page;
-import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.KeysetScrollPosition;
+import org.springframework.data.domain.Window;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -72,8 +72,8 @@ public Optional<ProjectDTO> findById(UUID projectId) {
 
     @Override
     @Transactional(readOnly = true)
-    public Page<ProjectDTO> findAll(Pageable pageable) {
-        return this.projectSearchService.findAll(pageable).map(this.projectMapper::toDTO);
+    public Window<ProjectDTO> findAll(KeysetScrollPosition position, int limit) {
+        return this.projectSearchService.findAll(position, limit).map(this.projectMapper::toDTO);
     }
 
     @Override

packages/sirius-web/backend/sirius-web-application/src/main/java/org/eclipse/sirius/web/application/project/services/api/IProjectApplicationService.java

@@ -20,8 +20,8 @@
 import org.eclipse.sirius.web.application.project.dto.DeleteProjectInput;
 import org.eclipse.sirius.web.application.project.dto.ProjectDTO;
 import org.eclipse.sirius.web.application.project.dto.RenameProjectInput;
-import org.springframework.data.domain.Page;
-import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.KeysetScrollPosition;
+import org.springframework.data.domain.Window;
 
 /**
  * Application services used to manipulate projects.
@@ -31,7 +31,7 @@
 public interface IProjectApplicationService {
     Optional<ProjectDTO> findById(UUID id);
 
-    Page<ProjectDTO> findAll(Pageable pageable);
+    Window<ProjectDTO> findAll(KeysetScrollPosition position, int limit);
 
     IPayload createProject(CreateProjectInput input);
 

packages/sirius-web/backend/sirius-web-application/src/main/resources/schema/siriusweb.graphqls

@@ -1,6 +1,6 @@
 extend type Viewer {
   project(projectId: ID!): Project
-  projects(page: Int!, limit: Int!): ViewerProjectsConnection!
+  projects(after: String, before: String, first: Int, last: Int): ViewerProjectsConnection!
   projectTemplates(page: Int!, limit: Int!): ViewerProjectTemplatesConnection!
 }
 
@@ -11,6 +11,7 @@ type ViewerProjectsConnection {
 
 type ViewerProjectsEdge {
   node: Project!
+  cursor: String!
 }
 
 type Project {

packages/sirius-web/backend/sirius-web-domain/src/main/java/org/eclipse/sirius/web/domain/boundedcontexts/project/repositories/IProjectRepository.java

@@ -16,14 +16,14 @@
 
 import org.eclipse.sirius.web.domain.boundedcontexts.project.Project;
 import org.springframework.data.repository.ListCrudRepository;
-import org.springframework.data.repository.ListPagingAndSortingRepository;
 import org.springframework.stereotype.Repository;
 
+
 /**
  * Repository used to persist the project aggregate.
  *
  * @author sbegaudeau
  */
 @Repository
-public interface IProjectRepository extends ListPagingAndSortingRepository<Project, UUID>, ListCrudRepository<Project, UUID>, ProjectSearchRepository<Project, UUID> {
+public interface IProjectRepository extends ListCrudRepository<Project, UUID>, ProjectSearchRepository<Project, UUID> {
 }

packages/sirius-web/backend/sirius-web-domain/src/main/java/org/eclipse/sirius/web/domain/boundedcontexts/project/repositories/ProjectSearchRepository.java

@@ -12,11 +12,12 @@
  *******************************************************************************/
 package org.eclipse.sirius.web.domain.boundedcontexts.project.repositories;
 
+import java.util.List;
 import java.util.Optional;
+import java.util.UUID;
 
 import org.eclipse.sirius.components.annotations.RepositoryFragment;
-import org.springframework.data.domain.Page;
-import org.springframework.data.domain.Pageable;
+import org.eclipse.sirius.web.domain.boundedcontexts.project.Project;
 
 /**
  * Fragment interface used to search projects.
@@ -32,5 +33,7 @@ public interface ProjectSearchRepository<T, ID> {
 
     Optional<T> findById(ID id);
 
-    Page<T> findAll(Pageable pageable);
+    List<Project> findAllBefore(UUID cursorProjectId, int limit);
+
+    List<Project> findAllAfter(UUID cursorProjectId, int limit);
 }