From 6300fb37adf7ce81fa2fe2b23e6e8cf40ff9c3c1 Mon Sep 17 00:00:00 2001
From: Sam Brannen <sam@sambrannen.com>
Date: Wed, 27 Sep 2023 16:35:31 +0200
Subject: [PATCH] Include '?' for null-safe navigation in SpEL AST
 representations

Prior to this commit, if a Spring Expression Language (SpEL) expression
contained property, field, or method references using the null-safe
navigation operator (?.), the generated AST String representation
incorrectly omitted the '?' characters.

For example, 'myProperty?.myMethod()' had a generated AST string
representation of 'myProperty.myMethod()'.

This commit addresses this by introducing isNullSafe() in
MethodReference and reworking the logic in
CompoundExpression.toStringAST().

Closes gh-31326
---
 .../expression/spel/ast/CompoundExpression.java          | 8 +++++++-
 .../expression/spel/ast/MethodReference.java             | 9 +++++++++
 .../springframework/expression/spel/ParsingTests.java    | 1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/CompoundExpression.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/CompoundExpression.java
index 01745e65cfc6..8a540a908dc6 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/CompoundExpression.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/CompoundExpression.java
@@ -28,7 +28,9 @@
 
 /**
  * Represents a DOT separated expression sequence, such as
- * {@code property1.property2.methodOne()}.
+ * {@code property1.property2.methodOne()} or
+ * {@code property1?.property2?.methodOne()} when the null-safe navigation
+ * operator is used.
  *
  * <p>May also contain array/collection/map indexers, such as
  * {@code property1[0].property2['key']}.
@@ -122,6 +124,10 @@ public String toStringAST() {
 				// Don't append a '.' if the next child is an Indexer.
 				// For example, we want 'myVar[0]' instead of 'myVar.[0]'.
 				if (!(nextChild instanceof Indexer)) {
+					if ((nextChild instanceof MethodReference methodRef && methodRef.isNullSafe()) ||
+						(nextChild instanceof PropertyOrFieldReference pofRef && pofRef.isNullSafe())) {
+						sb.append('?');
+					}
 					sb.append('.');
 				}
 			}
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/MethodReference.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/MethodReference.java
index 33756cab0e78..e79e6a9affeb 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/MethodReference.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/MethodReference.java
@@ -50,6 +50,7 @@
  *
  * @author Andy Clement
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.0
  */
 public class MethodReference extends SpelNodeImpl {
@@ -72,6 +73,14 @@ public MethodReference(boolean nullSafe, String methodName, int startPos, int en
 	}
 
 
+	/**
+	 * Does this node represent a null-safe method reference?
+	 * @since 6.0.13
+	 */
+	public final boolean isNullSafe() {
+		return this.nullSafe;
+	}
+
 	/**
 	 * Get the name of the referenced method.
 	 */
diff --git a/spring-expression/src/test/java/org/springframework/expression/spel/ParsingTests.java b/spring-expression/src/test/java/org/springframework/expression/spel/ParsingTests.java
index eea5e2e33330..6eeab7d6180b 100644
--- a/spring-expression/src/test/java/org/springframework/expression/spel/ParsingTests.java
+++ b/spring-expression/src/test/java/org/springframework/expression/spel/ParsingTests.java
@@ -47,6 +47,7 @@ class Miscellaneous {
 		void compoundExpressions() {
 			parseCheck("property1.property2.methodOne()");
 			parseCheck("property1[0].property2['key'].methodOne()");
+			parseCheck("property1?.methodOne()?.property2?.methodTwo()");
 		}
 
 		@Test