From 812ce76290c8f2be8450cb5eb6726b9bc0096086 Mon Sep 17 00:00:00 2001
From: Lukas Karsch <lk224@hdm-stuttgart.de>
Date: Mon, 25 Dec 2023 17:31:45 +0100
Subject: [PATCH] #42 entity mapper
---
.../hdm/mi/growbros/util/EntityMapper.java | 96 +++++++++++++++++++
.../mi/growbros/util/EntityMapperTest.java | 67 +++++++++++++
2 files changed, 163 insertions(+)
create mode 100644 src/main/java/hdm/mi/growbros/util/EntityMapper.java
create mode 100644 src/test/java/hdm/mi/growbros/util/EntityMapperTest.java
diff --git a/src/main/java/hdm/mi/growbros/util/EntityMapper.java b/src/main/java/hdm/mi/growbros/util/EntityMapper.java
new file mode 100644
index 0000000..333a09e
--- /dev/null
+++ b/src/main/java/hdm/mi/growbros/util/EntityMapper.java
@@ -0,0 +1,96 @@
+package hdm.mi.growbros.util;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.List;
+
+@Component
+public class EntityMapper {
+ private final static Logger log = LoggerFactory.getLogger(EntityMapper.class);
+
+ /**
+ * Updates fields of an existing entity based on non-null values from an update request.
+ * This method is designed for use in PATCH operations within a Spring Boot application.
+ *
+ * <p>
+ * The {@code map} method facilitates the partial update of an existing entity by mapping non-null
+ * fields from an update request object to the corresponding fields in the existing entity.
+ * Fields in the update request with null values are excluded from the update.
+ * </p>
+ *
+ * <p>
+ * Usage example:
+ * <pre>{@code
+ * // Create an instance of the class containing the map method
+ * EntityMapper entityMapper = new EntityMapper();
+ *
+ * // Create an instance of the existing entity and update request
+ * ExistingEntity existingEntity = // ... (initialize existing entity)
+ * UpdateRequest updateRequest = // ... (initialize update request)
+ *
+ * // Perform the partial update
+ * entityMapper.map(updateRequest, existingEntity);
+ * }</pre>
+ * </p>
+ *
+ * <p>
+ * Note: This class assumes proper usage in a Spring Boot application, particularly for PATCH
+ * operations, where only specified fields need to be updated without affecting the entire entity.
+ * </p>
+ *
+ * @param updateRequest The object containing fields with non-null values to be used for updating.
+ * @param existingEntity The entity object to be updated with non-null values from the update request.
+ */
+ public void map(Object updateRequest, Object existingEntity) {
+ if (updateRequest == null) {
+ log.warn("Update request was null, no mapping will take place");
+ return;
+ }
+ if (existingEntity == null) {
+ log.warn("Existing entity was null, no mapping will take place");
+ return;
+ }
+
+ final Field[] allUpdaterFields = updateRequest.getClass().getDeclaredFields();
+ final List<Field> toUpdate = new ArrayList<>();
+
+ for (Field updaterField : allUpdaterFields) {
+ updaterField.setAccessible(true);
+ try {
+ if (updaterField.get(updateRequest) != null && !"this$0".equals(updaterField.getName())) {
+ toUpdate.add(updaterField);
+ }
+ } catch (IllegalAccessException e) {
+ log.error("Illegal access exception while mapping object", e);
+ }
+ }
+
+ updateFields(toUpdate, updateRequest, existingEntity);
+ }
+
+ private Field getFieldForName(String name, Object o) {
+ var fields = o.getClass().getDeclaredFields();
+ for (Field f : fields) {
+ if (name.equals(f.getName())) return f;
+ }
+ throw new IllegalArgumentException("No field with declared name '" + name + "' is present on this object");
+ }
+
+ private void updateFields(List<Field> toUpdate, Object updateRequest, Object existingEntity) {
+ for (Field updateField : toUpdate) {
+ try {
+ updateField.setAccessible(true);
+ Field entityField = getFieldForName(updateField.getName(), existingEntity);
+ entityField.setAccessible(true);
+ final Object newValue = updateField.get(updateRequest);
+ entityField.set(existingEntity, newValue);
+ } catch (IllegalAccessException e) {
+ log.error("Illegal access exception while mapping object", e);
+ }
+ }
+ }
+}
diff --git a/src/test/java/hdm/mi/growbros/util/EntityMapperTest.java b/src/test/java/hdm/mi/growbros/util/EntityMapperTest.java
new file mode 100644
index 0000000..6a34477
--- /dev/null
+++ b/src/test/java/hdm/mi/growbros/util/EntityMapperTest.java
@@ -0,0 +1,67 @@
+package hdm.mi.growbros.util;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class EntityMapperTest {
+ private EntityMapper entityMapper;
+
+ @BeforeEach
+ void setup() {
+ entityMapper = new EntityMapper();
+ }
+
+ @Test
+ void shouldIgnore_whenEitherArgument_isNull() {
+ //arrange
+ final Entity entity = getBaseEntity();
+ final UpdaterObject updater = new UpdaterObject();
+
+ //act and assert
+ assertAll(
+ () -> assertDoesNotThrow(() -> entityMapper.map(null, entity)),
+ () -> assertDoesNotThrow(() -> entityMapper.map(updater, null))
+ );
+ }
+
+ @Test
+ void shouldUpdate_toNewValues() {
+ //arrange
+ final Entity entity = getBaseEntity();
+
+ final UpdaterObject updater = new UpdaterObject();
+ final String expected = "UPDATED value 1";
+ updater.value1 = expected;
+
+ //act
+ entityMapper.map(updater, entity);
+
+ //assert
+ assertAll(
+ () -> assertEquals(1, entity.id),
+ () -> assertEquals(expected, entity.value1),
+ () -> assertEquals("Value 2", entity.value2)
+ );
+ }
+
+ private class UpdaterObject {
+ private String value1;
+ private String value2;
+ }
+
+ private class Entity {
+ private int id;
+ private String value1;
+ private String value2;
+ }
+
+ private Entity getBaseEntity() {
+ final Entity entity = new Entity();
+ entity.id = 1;
+ entity.value1 = "Value 1";
+ entity.value2 = "Value 2";
+ return entity;
+ }
+}
--
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