From 12346fa9294908f85e48b598ba3c95c391c07299 Mon Sep 17 00:00:00 2001
From: Ting-Lan Wang <ting-lan.wang@oracle.com>
Date: Fri, 19 Sep 2025 09:48:21 -0400
Subject: [PATCH] support case insensitive field matching

---
 oracle/oracle.go     | 12 ++++++++++++
 oracle/query.go      | 20 ++++++++++++++++++--
 tests/config_test.go | 42 ++++++++++++++++++++++++++++++++++++++----
 3 files changed, 68 insertions(+), 6 deletions(-)

diff --git a/oracle/oracle.go b/oracle/oracle.go
index ee7e0a2..b4b7efa 100644
--- a/oracle/oracle.go
+++ b/oracle/oracle.go
@@ -109,6 +109,18 @@ func (d Dialector) Initialize(db *gorm.DB) (err error) {
 	callback.Update().Replace("gorm:update", Update)
 	callback.Query().Before("gorm:query").Register("oracle:before_query", BeforeQuery)
 
+	if d.SkipQuoteIdentifiers {
+		// When identifiers are not quoted, columns are returned by Oracle in uppercase.
+		// Fields in the models may be lower case for compatibility with other databases.
+		// Match them up with the fields using the column mapping.
+		oracleCaseHandler := "oracle:case_handler"
+		if callback.Query().Get(oracleCaseHandler) == nil {
+			if err := callback.Query().Before("gorm:query").Register(oracleCaseHandler, MismatchedCaseHandler); err != nil {
+				return err
+			}
+		}
+	}
+
 	maps.Copy(db.ClauseBuilders, OracleClauseBuilders())
 
 	if d.Conn == nil {
diff --git a/oracle/query.go b/oracle/query.go
index 5a45c26..ca63b0a 100644
--- a/oracle/query.go
+++ b/oracle/query.go
@@ -39,9 +39,10 @@
 package oracle
 
 import (
-	"gorm.io/gorm"
 	"regexp"
 	"strings"
+
+	"gorm.io/gorm"
 )
 
 // Identifies the table name alias provided as
@@ -63,5 +64,20 @@ func BeforeQuery(db *gorm.DB) {
 			}
 		}
 	}
-	return
+}
+
+// MismatchedCaseHandler handles Oracle Case Insensitivity.
+// When identifiers are not quoted, columns are returned by Oracle in uppercase.
+// Fields in the models may be lower case for compatibility with other databases.
+// Match them up with the fields using the column mapping.
+func MismatchedCaseHandler(gormDB *gorm.DB) {
+	if gormDB.Statement == nil || gormDB.Statement.Schema == nil {
+		return
+	}
+	if len(gormDB.Statement.Schema.Fields) > 0 && gormDB.Statement.ColumnMapping == nil {
+		gormDB.Statement.ColumnMapping = map[string]string{}
+	}
+	for _, field := range gormDB.Statement.Schema.Fields {
+		gormDB.Statement.ColumnMapping[strings.ToUpper(field.DBName)] = field.Name
+	}
 }
diff --git a/tests/config_test.go b/tests/config_test.go
index a9dd435..7fff870 100644
--- a/tests/config_test.go
+++ b/tests/config_test.go
@@ -78,23 +78,57 @@ func TestSkipQuoteIdentifiers(t *testing.T) {
 		t.Errorf("Failed to get column: name")
 	}
 
+	student := Student{ID: 1, Name: "John"}
+	if err := db.Model(&Student{}).Create(&student).Error; err != nil {
+		t.Errorf("Failed to insert student, got %v", err)
+	}
+
+	var result Student
+	if err := db.First(&result).Error; err != nil {
+		t.Errorf("Failed to query first student, got %v", err)
+	}
+
+	if result.ID != student.ID {
+		t.Errorf("id should be %v, but got %v", student.ID, result.ID)
+	}
+
+	if result.Name != student.Name {
+		t.Errorf("name should be %v, but got %v", student.Name, result.Name)
+	}
+}
+
+func TestSkipQuoteIdentifiersSQL(t *testing.T) {
+	db, err := openTestDBWithOptions(
+		&oracle.Config{SkipQuoteIdentifiers: true},
+		&gorm.Config{Logger: newLogger})
+	if err != nil {
+		t.Fatalf("failed to connect database, got error %v", err)
+	}
 	dryrunDB := db.Session(&gorm.Session{DryRun: true})
 
-	result := dryrunDB.Model(&Student{}).Create(&Student{ID: 1, Name: "John"})
+	insertedStudent := Student{ID: 1, Name: "John"}
+	result := dryrunDB.Model(&Student{}).Create(&insertedStudent)
+
 	if !regexp.MustCompile(`^INSERT INTO STUDENTS \(name,id\) VALUES \(:1,:2\)$`).MatchString(result.Statement.SQL.String()) {
 		t.Errorf("invalid insert SQL, got %v", result.Statement.SQL.String())
 	}
 
-	result = dryrunDB.First(&Student{})
+	// Test First
+	var firstStudent Student
+	result = dryrunDB.First(&firstStudent)
+
 	if !regexp.MustCompile(`^SELECT \* FROM STUDENTS ORDER BY STUDENTS\.id FETCH NEXT 1 ROW ONLY$`).MatchString(result.Statement.SQL.String()) {
 		t.Fatalf("SQL should include selected names, but got %v", result.Statement.SQL.String())
 	}
 
-	result = dryrunDB.Find(&Student{ID: 1, Name: "John"})
-	if !regexp.MustCompile(`^SELECT \* FROM STUDENTS WHERE STUDENTS\.id = :1$`).MatchString(result.Statement.SQL.String()) {
+	// Test Find
+	var foundStudent Student
+	result = dryrunDB.Find(foundStudent, "id = ?", insertedStudent.ID)
+	if !regexp.MustCompile(`^SELECT \* FROM STUDENTS WHERE id = :1$`).MatchString(result.Statement.SQL.String()) {
 		t.Fatalf("SQL should include selected names, but got %v", result.Statement.SQL.String())
 	}
 
+	// Test Save
 	result = dryrunDB.Save(&Student{ID: 2, Name: "Mary"})
 	if !regexp.MustCompile(`^UPDATE STUDENTS SET name=:1 WHERE id = :2$`).MatchString(result.Statement.SQL.String()) {
 		t.Fatalf("SQL should include selected names, but got %v", result.Statement.SQL.String())