From b4490de97e131a512d3bf076161f6c656d8705f4 Mon Sep 17 00:00:00 2001
From: Stephano George <huohuo5230@gmail.com>
Date: Tue, 27 Sep 2022 17:13:14 +0800
Subject: [PATCH] Fix: Wrong value when Find with JOIN and same column name
 (#5711)

---
 scan.go             | 30 +++++++++++-------------------
 tests/joins_test.go | 30 ++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 19 deletions(-)

diff --git a/scan.go b/scan.go
index 2db431601..aa1dcd262 100644
--- a/scan.go
+++ b/scan.go
@@ -200,28 +200,20 @@ func Scan(rows Rows, db *DB, mode ScanMode) {
 
 			// Not Pluck
 			if sch != nil {
-				schFieldsCount := len(sch.Fields)
 				for idx, column := range columns {
-					if field := sch.LookUpField(column); field != nil && field.Readable {
-						if curIndex, ok := selectedColumnsMap[column]; ok {
-							fields[idx] = field // handle duplicate fields
-							offset := curIndex + 1
-							// handle sch inconsistent with database
-							// like Raw(`...`).Scan
-							if schFieldsCount > offset {
-								for fieldIndex, selectField := range sch.Fields[offset:] {
-									if selectField.DBName == column && selectField.Readable {
-										selectedColumnsMap[column] = curIndex + fieldIndex + 1
-										fields[idx] = selectField
-										break
-									}
-								}
+					for i, field := range sch.Fields[selectedColumnsMap[column]:] {
+						if field.DBName == column {
+							if field.Readable {
+								fields[idx] = field
+								selectedColumnsMap[column] += i + 1
 							}
-						} else {
-							fields[idx] = field
-							selectedColumnsMap[column] = idx
+							break
 						}
-					} else if names := strings.Split(column, "__"); len(names) > 1 {
+					}
+					if fields[idx] != nil {
+						continue
+					}
+					if names := strings.Split(column, "__"); len(names) > 1 {
 						if rel, ok := sch.Relationships.Relations[names[0]]; ok {
 							if field := rel.FieldSchema.LookUpField(strings.Join(names[1:], "__")); field != nil && field.Readable {
 								fields[idx] = field
diff --git a/tests/joins_test.go b/tests/joins_test.go
index 4908e5ba4..2271bd175 100644
--- a/tests/joins_test.go
+++ b/tests/joins_test.go
@@ -3,6 +3,7 @@ package tests_test
 import (
 	"regexp"
 	"sort"
+	"strings"
 	"testing"
 
 	"gorm.io/gorm"
@@ -229,3 +230,32 @@ func TestJoinWithSoftDeleted(t *testing.T) {
 		t.Fatalf("joins NamedPet and Account should not empty:%v", user2)
 	}
 }
+
+func TestJoinWithSameColumnName(t *testing.T) {
+	user := GetUser("TestJoinWithSameColumnName", Config{
+		Languages: 1,
+		Pets:      1,
+	})
+	DB.Create(user)
+	type UserSpeak struct {
+		UserID       uint
+		LanguageCode string
+	}
+	type Result struct {
+		User
+		UserSpeak
+		Language
+		Pet
+	}
+	results := make([]Result, 0, 1)
+	DB.Select("*").Table("users").Joins("JOIN user_speaks ON user_speaks.user_id = users.id").
+		Joins("JOIN languages ON languages.code = user_speaks.language_code").
+		Joins("LEFT OUTER JOIN pets ON pets.user_id = users.id").Find(&results)
+	if len(results) == 0 {
+		t.Fatalf("no record find")
+	} else if results[0].Pet.UserID == nil {
+		t.Fatalf("wrong user id in pet")
+	} else if !strings.Contains(results[0].Pet.Name, "_pet_") {
+		t.Fatalf("wrong pet name")
+	}
+}