Support size = 0 in PageJacksonModule

Author: nkonev

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/support/PageJacksonModule.java

@@ -38,6 +38,8 @@
  *
  * @author Pascal Büttiker
  * @author Olga Maciaszek-Sharma
+ * @author Pedro Mendes
+ * @author Nikita Konev
  */
 public class PageJacksonModule extends Module {
 
@@ -69,18 +71,22 @@ static class SimplePageImpl<T> implements Page<T> {
 				@JsonProperty("size") int size, @JsonProperty("totalElements") @JsonAlias({ "total-elements",
 						"total_elements", "totalelements", "TotalElements" }) long totalElements,
 				@JsonProperty("sort") Sort sort) {
-			PageRequest pageRequest;
-			if (sort != null) {
-				pageRequest = PageRequest.of(number, size, sort);
+			if (size > 0) {
+				PageRequest pageRequest;
+				if (sort != null) {
+					pageRequest = PageRequest.of(number, size, sort);
+				}
+				else {
+					pageRequest = PageRequest.of(number, size);
+				}
+				delegate = new PageImpl<>(content, pageRequest, totalElements);
 			}
 			else {
-				pageRequest = PageRequest.of(number, size);
+				delegate = new PageImpl<>(content);
 			}
-			delegate = new PageImpl<>(content, pageRequest, totalElements);
-
 		}
 
-		@JsonProperty
+		@JsonIgnore
 		@Override
 		public int getTotalPages() {
 			return delegate.getTotalPages();
@@ -104,7 +110,7 @@ public int getSize() {
 			return delegate.getSize();
 		}
 
-		@JsonProperty
+		@JsonIgnore
 		@Override
 		public int getNumberOfElements() {
 			return delegate.getNumberOfElements();
@@ -128,13 +134,13 @@ public Sort getSort() {
 			return delegate.getSort();
 		}
 
-		@JsonProperty
+		@JsonIgnore
 		@Override
 		public boolean isFirst() {
 			return delegate.isFirst();
 		}
 
-		@JsonProperty
+		@JsonIgnore
 		@Override
 		public boolean isLast() {
 			return delegate.isLast();
@@ -176,6 +182,18 @@ public Iterator<T> iterator() {
 			return delegate.iterator();
 		}
 
+		@JsonIgnore
+		@Override
+		public Pageable getPageable() {
+			return delegate.getPageable();
+		}
+
+		@JsonIgnore
+		@Override
+		public boolean isEmpty() {
+			return delegate.isEmpty();
+		}
+
 	}
 
 }

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/support/PageJacksonModuleTests.java

@@ -16,13 +16,18 @@
 
 package org.springframework.cloud.openfeign.support;
 
+import java.util.ArrayList;
+
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
 
 import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageImpl;
+import org.springframework.data.domain.Pageable;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -31,6 +36,8 @@
  *
  * @author Ruben Vervaeke
  * @author Olga Maciaszek-Sharma
+ * @author Pedro Mendes
+ * @author Nikita Konev
  */
 public class PageJacksonModuleTests {
 
@@ -40,6 +47,7 @@ public class PageJacksonModuleTests {
 	public static void initialize() {
 		objectMapper = new ObjectMapper();
 		objectMapper.registerModule(new PageJacksonModule());
+		objectMapper.registerModule(new SortJacksonModule());
 	}
 
 	@ParameterizedTest
@@ -58,4 +66,40 @@ public void deserializePage(String totalElements) throws JsonProcessingException
 		assertThat(result.getPageable().getPageNumber()).isEqualTo(1);
 	}
 
+	@Test
+	public void serializeAndDeserializeEmpty() throws JsonProcessingException {
+		// Given
+		PageImpl<Object> objects = new PageImpl<>(new ArrayList<>());
+		String pageJson = objectMapper.writeValueAsString(objects);
+		// When
+		Page<?> result = objectMapper.readValue(pageJson, Page.class);
+		// Then
+		assertThat(result).isNotNull();
+		assertThat(result.getTotalElements()).isEqualTo(0);
+		assertThat(result.getContent()).hasSize(0);
+	}
+
+	@Test
+	public void serializeAndDeserializeFilledMultiple() throws JsonProcessingException {
+		// Given
+		ArrayList<Object> strings0 = new ArrayList<>();
+		strings0.add("first element");
+		strings0.add("second element");
+		PageImpl<Object> objects = new PageImpl<>(strings0, Pageable.ofSize(2), 100);
+		assertThat(objects.getContent()).hasSize(2);
+		assertThat(objects.getPageable().getPageSize()).isEqualTo(2);
+
+		String pageJson = objectMapper.writeValueAsString(objects);
+		// When
+		Page<?> result = objectMapper.readValue(pageJson, Page.class);
+		// Then
+		assertThat(result).isNotNull();
+		assertThat(result.getTotalElements()).isEqualTo(100);
+		assertThat(result.getContent()).hasSize(2);
+		assertThat(result.getContent().get(0)).isEqualTo("first element");
+		assertThat(result.getContent().get(1)).isEqualTo("second element");
+		assertThat(result.getPageable().getPageSize()).isEqualTo(2);
+		assertThat(result.getPageable().getPageNumber()).isEqualTo(0);
+	}
+
 }