Allow escaping of '?' using '??' in SQL expression

foundation/org.eclipse.persistence.core/src/main/java/org/eclipse/persistence/expressions/Expression.java

@@ -1981,6 +1981,11 @@ public Expression sql(String sql, List arguments) {
         int start = 0;
         int index = sql.indexOf('?');
         while (index != -1) {
+            // ? can be escaped as ?? to support ? as a native SQL operator (e.g. on Postgres)
+            if (index < sql.length() - 1 && sql.charAt(index + 1) == '?') {
+                index = sql.indexOf('?', index + 2);
+                continue;
+            }
             v.add(sql.substring(start, index));
             start = index + 1;
             index = sql.indexOf('?', start);
@@ -1989,6 +1994,14 @@ public Expression sql(String sql, List arguments) {
             v.add(sql.substring(start, sql.length()));
         }
         anOperator.printsAs(v);
+        //Postgres expects '??' as an escape mechanism for '?' in parameterized queries
+        //https://jdbc.postgresql.org/documentation/query/#using-the-statement-or-preparedstatement-interface
+        //On other platforms, replace ?? with ? in code which is passed as a part of SQL into DB
+        if (getSession() == null || !getSession().getPlatform().isPostgreSQL()) {
+            for (int i = 0; i < anOperator.getDatabaseStrings().length; i++) {
+                anOperator.getDatabaseStrings()[i] = anOperator.getDatabaseStrings()[i].replace("??", "?");
+            }
+        }
         anOperator.bePrefix();
         anOperator.setNodeClass(ClassConstants.FunctionExpression_Class);
 

foundation/org.eclipse.persistence.core/src/main/java/org/eclipse/persistence/internal/jpa/jpql/ExpressionBuilderVisitor.java

@@ -1099,6 +1099,8 @@ public void visit(FunctionExpression expression) {
                 }
 
                 queryExpression = queryExpressions.remove(0);
+                // ensure the session is set for the 'SQL' operator
+                queryExpression.getBuilder().setSession(queryContext.getSession());
 
                 // SQL
                 if (identifier == org.eclipse.persistence.jpa.jpql.parser.Expression.SQL) {

jpa/eclipselink.jpa.test.jse/src/it/java/org/eclipse/persistence/jpa/json/TestJson.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2023 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0 which is available at
@@ -30,6 +30,7 @@
 import org.eclipse.persistence.jpa.test.framework.Emf;
 import org.eclipse.persistence.jpa.test.framework.EmfRunner;
 import org.eclipse.persistence.jpa.test.framework.Property;
+import org.eclipse.persistence.sessions.Session;
 import org.junit.Assert;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -254,4 +255,32 @@ public void testSelectJsonInWhereCondition() {
         }
     }
 
+    @Test
+    public void testEscapedQuestionMarkInSQLOperator() {
+        EntityManager em = emf.createEntityManager();
+
+        if (emf.unwrap(Session.class).getPlatform().isOracle()) {
+            JsonValue value = Json.createObjectBuilder()
+                    .add("id", "1007")
+                    .build();
+            try {
+                em.getTransaction().begin();
+                JsonEntity e = new JsonEntity(1007, value);
+                em.persist(e);
+                em.flush();
+                em.getTransaction().commit();
+                em.clear();
+
+                JsonEntity dbValue = em.createQuery(
+                    "SELECT v FROM JsonEntity v WHERE SQL('JSON_EXISTS(?, ''$??(@.id == 1007)'')', v.value)", JsonEntity.class)
+                    .getSingleResult();
+                Assert.assertEquals(value, dbValue.getValue());
+            } finally {
+                if (em.getTransaction().isActive()) {
+                    em.getTransaction().rollback();
+                }
+                em.close();
+            }
+        }
+    }
 }