Fix bug in JDBC SaveMode.ON_GET_ATTRIBUTE

Author: felixscheinost

spring-session-jdbc/src/integration-test/java/org/springframework/session/jdbc/AbstractJdbcIndexedSessionRepositoryITests.java

@@ -45,6 +45,7 @@
 import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.session.FindByIndexNameSessionRepository;
 import org.springframework.session.MapSession;
+import org.springframework.session.SaveMode;
 import org.springframework.session.config.SessionRepositoryCustomizer;
 import org.springframework.session.jdbc.JdbcIndexedSessionRepository.JdbcSession;
 import org.springframework.session.jdbc.config.annotation.web.http.EnableJdbcHttpSession;
@@ -819,6 +820,33 @@ void saveNewSessionAttributeConcurrently() {
 		}
 	}
 
+	@Test
+	void savesWhenSaveModeIsOnGetAttributeAndANewAttributeIsSetAndGet() {
+		try {
+			// Prerequisite: SaveMode.ON_GET_ATTRIBUTE is enabled
+			this.repository.setSaveMode(SaveMode.ON_GET_ATTRIBUTE);
+
+			// Step 1: Save session
+			JdbcSession initialSession = this.repository.createSession();
+			this.repository.save(initialSession);
+
+			// Step 2: Load session again, set an attribute and immediately get it again
+			JdbcSession session = this.repository.findById(initialSession.getId());
+			String attributeName = "attribute1";
+			String attributeValue = "value1";
+			session.setAttribute(attributeName, attributeValue);
+			session.getAttribute(attributeName);
+			this.repository.save(session);
+
+			// Step3: Load session 3rd time, verify that attribute is set correctly
+			assertThat((String) this.repository.findById(initialSession.getId()).getAttribute(attributeName))
+					.isEqualTo(attributeValue);
+		}
+		finally {
+			this.repository.setSaveMode(SaveMode.ON_SET_ATTRIBUTE);
+		}
+	}
+
 	private String getSecurityName() {
 		return this.context.getAuthentication().getName();
 	}

spring-session-jdbc/src/main/java/org/springframework/session/jdbc/JdbcIndexedSessionRepository.java

@@ -728,7 +728,9 @@ public <T> T getAttribute(String attributeName) {
 			T attributeValue = supplier.get();
 			if (attributeValue != null
 					&& JdbcIndexedSessionRepository.this.saveMode.equals(SaveMode.ON_GET_ATTRIBUTE)) {
-				this.delta.put(attributeName, DeltaValue.UPDATED);
+				this.delta.merge(attributeName, DeltaValue.UPDATED, (oldDeltaValue, deltaValue) ->
+						(oldDeltaValue == DeltaValue.ADDED) ? oldDeltaValue : deltaValue
+				);
 			}
 			return attributeValue;
 		}