Replace Page<> with Slice<> for pagination operations

According to: https://www.youtube.com/watch?v=wi6h9ox1wwM

src/main/java/by/andd3dfx/templateapp/controllers/ArticleController.java

@@ -12,9 +12,8 @@
 import java.util.List;
 import javax.validation.constraints.NotNull;
 import lombok.RequiredArgsConstructor;
-import org.springframework.data.domain.Page;
-import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.web.PageableDefault;
 import org.springframework.data.web.SortDefault;
@@ -108,7 +107,7 @@ public void deleteArticle(
         articleService.delete(id);
     }
 
-    @ApiOperation(value = "Read articles paged", response = Page.class)
+    @ApiOperation(value = "Read articles paged", response = Slice.class)
     @ApiResponses(value = {
         @ApiResponse(code = 200, message = "Articles successfully retrieved"),
     })
@@ -125,7 +124,7 @@ public void deleteArticle(
                 "Multiple sort criteria are supported.",
             defaultValue = "title,ASC")
     })
-    public Page<ArticleDto> readArticlesPaged(
+    public Slice<ArticleDto> readArticlesPaged(
         @PageableDefault(page = 0, size = 50)
         @SortDefault.SortDefaults({
             @SortDefault(sort = "title", direction = Sort.Direction.ASC)

src/main/java/by/andd3dfx/templateapp/dto/LocationDto.java

@@ -10,6 +10,7 @@
 @Data
 @JsonInclude(JsonInclude.Include.NON_NULL)
 public class LocationDto {
+
     private String country;
     private String city;
 }

src/main/java/by/andd3dfx/templateapp/persistence/dao/ArticleRepository.java

@@ -1,13 +1,18 @@
 package by.andd3dfx.templateapp.persistence.dao;
 
 import by.andd3dfx.templateapp.persistence.entities.Article;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
+import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
 import org.springframework.stereotype.Repository;
 
 import java.util.List;
 
 @Repository
-public interface ArticleRepository extends PagingAndSortingRepository<Article, Long>, ArticleRepositoryCustom {
+public interface ArticleRepository extends CrudRepository<Article, Long>, ArticleRepositoryCustom {
 
     List<Article> getArticleByCountryNCity(String country, String city);
+
+    Slice<Article> findAll(Pageable pageable);
 }

src/main/java/by/andd3dfx/templateapp/persistence/entities/Location.java

@@ -8,6 +8,7 @@
 @NoArgsConstructor
 @Data
 public class Location {
+
     private String country;
     private String city;
 }

src/main/java/by/andd3dfx/templateapp/services/IArticleService.java

@@ -2,8 +2,8 @@
 
 import by.andd3dfx.templateapp.dto.ArticleDto;
 import by.andd3dfx.templateapp.dto.ArticleUpdateDto;
-import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
 
 import java.util.List;
 
@@ -17,7 +17,7 @@ public interface IArticleService {
 
     void delete(Long id);
 
-    Page<ArticleDto> getAll(Pageable pageable);
+    Slice<ArticleDto> getAll(Pageable pageable);
 
     List<ArticleDto> getArticleByLocation(String country, String city);
 }

src/main/java/by/andd3dfx/templateapp/services/impl/ArticleService.java

@@ -11,6 +11,7 @@
 import org.springframework.dao.EmptyResultDataAccessException;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -62,8 +63,8 @@ public void delete(Long id) {
 
     @Transactional(readOnly = true)
     @Override
-    public Page<ArticleDto> getAll(Pageable pageable) {
-        final Page<Article> pagedResult = articleRepository.findAll(pageable);
+    public Slice<ArticleDto> getAll(Pageable pageable) {
+        Slice<Article> pagedResult = articleRepository.findAll(pageable);
         return pagedResult.map(articleMapper::toArticleDto);
     }
 

src/test/java/by/andd3dfx/templateapp/SpringBootTemplateApplicationTests.java

@@ -2,8 +2,6 @@
 
 import by.andd3dfx.templateapp.dto.ArticleDto;
 import by.andd3dfx.templateapp.dto.LocationDto;
-import by.andd3dfx.templateapp.persistence.dao.ArticleRepository;
-import by.andd3dfx.templateapp.persistence.entities.Article;
 import by.andd3dfx.templateapp.services.impl.ArticleService;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -22,14 +20,14 @@ class SpringBootTemplateApplicationTests {
 
 	@Test
 	void contextLoads() {
-		ArticleDto article = new ArticleDto();
+		var article = new ArticleDto();
 		article.setTitle("Voina i mir");
 		article.setAuthor("Lev Tolstoj");
 		article.setText("Some text");
 		article.setLocation(new LocationDto("US", "New York"));
-		ArticleDto createdArticle = articleService.create(article);
+		var createdArticle = articleService.create(article);
 
-		ArticleDto savedArticle = articleService.get(createdArticle.getId());
+		var savedArticle = articleService.get(createdArticle.getId());
 		assertThat(savedArticle.getTitle(), is(article.getTitle()));
 		assertThat(savedArticle.getAuthor(), is(article.getAuthor()));
 		assertThat(savedArticle.getText(), is(article.getText()));

src/test/java/by/andd3dfx/templateapp/persistence/dao/ArticleRepositoryTest.java

@@ -0,0 +1,76 @@
+package by.andd3dfx.templateapp.persistence.dao;
+
+import by.andd3dfx.templateapp.IntegrationTestInitializer;
+import by.andd3dfx.templateapp.persistence.entities.Article;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Sort;
+import org.springframework.test.context.ContextConfiguration;
+
+import java.time.LocalDateTime;
+import java.util.Arrays;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+@ContextConfiguration(initializers = IntegrationTestInitializer.class)
+@SpringBootTest
+class ArticleRepositoryTest {
+
+    @Autowired
+    private ArticleRepository repository;
+
+    private Article entity;
+    private Article entity2;
+    private Article entity3;
+
+    @BeforeEach
+    public void setup() {
+        repository.deleteAll();
+        entity = buildArticle("Ivan", "HD", LocalDateTime.parse("2010-12-03T10:15:30"));
+        entity2 = buildArticle("Vasily", "HD", LocalDateTime.parse("2011-12-03T10:15:30"));
+        entity3 = buildArticle("Ivan", "4K", LocalDateTime.parse("2012-12-03T10:15:30"));
+        repository.saveAll(Arrays.asList(entity, entity2, entity3));
+    }
+
+    @AfterEach
+    public void tearDown() {
+        repository.deleteAll();
+    }
+
+    @Test
+    public void findAll() {
+        var result = repository.findAll(Pageable.ofSize(10));
+
+        assertThat("Wrong records amount", result.getNumberOfElements(), is(3));
+    }
+
+    @Test
+    public void findAll_withPageNSizeNSorting() {
+        var result = repository.findAll(PageRequest.of(0, 2, Sort.by("title", "summary")));
+
+        assertThat("Wrong records amount", result.getNumberOfElements(), is(2));
+        var articles = result.getContent();
+
+        assertThat(articles.get(0).getTitle(), is(entity3.getTitle()));
+        assertThat(articles.get(0).getSummary(), is(entity3.getSummary()));
+
+        assertThat(articles.get(1).getTitle(), is(entity.getTitle()));
+        assertThat(articles.get(1).getSummary(), is(entity.getSummary()));
+    }
+
+    private static Article buildArticle(String title, String summary, LocalDateTime timestamp) {
+        var result = new Article();
+        result.setTitle(title);
+        result.setSummary(summary);
+        result.setText("any text");
+        result.setTimestamp(timestamp);
+        result.setAuthor("Some author");
+        return result;
+    }
+}