Added offset when scanning the result back to struct, close #5143

commit 9a2058164d44c98d7b586b87bed1757f89d6fad7
Author: Jinzhu <wosmvp@gmail.com>
Date:   Thu Mar 17 22:34:19 2022 +0800

    Refactor #5143

commit c259de21768936428c9d89f7b31afb95b8acb36a
Author: Hasan <mr.k779@outlook.com>
Date:   Mon Mar 14 20:04:01 2022 +0545

    Update scan_test.go

commit 09f127b49151a52fbb8b354a03e6610d4f70262f
Author: Hasan <mr.k779@outlook.com>
Date:   Mon Mar 14 19:23:47 2022 +0545

    Added test for scanning embedded data into structs

commit aeaca493cf412def7813d36fd6a68acc832bf79f
Author: Hasan <mr.k779@outlook.com>
Date:   Tue Mar 8 04:08:16 2022 +0600

    Added offset when scanning the result back to struct

scan.go

@@ -156,10 +156,11 @@ func Scan(rows *sql.Rows, db *DB, mode ScanMode) {
 		}
 	default:
 		var (
-			fields       = make([]*schema.Field, len(columns))
+			fields             = make([]*schema.Field, len(columns))
-			joinFields   [][2]*schema.Field
+			selectedColumnsMap = make(map[string]int, len(columns))
-			sch          = db.Statement.Schema
+			joinFields         [][2]*schema.Field
-			reflectValue = db.Statement.ReflectValue
+			sch                = db.Statement.Schema
+			reflectValue       = db.Statement.ReflectValue
 		)
 
 		if reflectValue.Kind() == reflect.Interface {
@@ -194,7 +195,18 @@ func Scan(rows *sql.Rows, db *DB, mode ScanMode) {
 			if sch != nil {
 				for idx, column := range columns {
 					if field := sch.LookUpField(column); field != nil && field.Readable {
-						fields[idx] = field
+						if curIndex, ok := selectedColumnsMap[column]; ok {
+							for fieldIndex, selectField := range sch.Fields[curIndex:] {
+								if selectField.DBName == column && selectField.Readable {
+									selectedColumnsMap[column] = curIndex + fieldIndex + 1
+									fields[idx] = selectField
+									break
+								}
+							}
+						} else {
+							fields[idx] = field
+							selectedColumnsMap[column] = idx
+						}
 					} else 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 {

tests/go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/golang-sql/civil v0.0.0-20220223132316-b832511892a9 // indirect
 	github.com/google/uuid v1.3.0
 	github.com/jackc/pgx/v4 v4.15.0 // indirect
-	github.com/jinzhu/now v1.1.4
+	github.com/jinzhu/now v1.1.5
 	github.com/lib/pq v1.10.4
 	github.com/mattn/go-sqlite3 v1.14.12 // indirect
 	golang.org/x/crypto v0.0.0-20220315160706-3147a52a75dd // indirect

tests/scan_test.go

@@ -10,6 +10,11 @@ import (
 	. "gorm.io/gorm/utils/tests"
 )
 
+type PersonAddressInfo struct {
+	Person  *Person  `gorm:"embedded"`
+	Address *Address `gorm:"embedded"`
+}
+
 func TestScan(t *testing.T) {
 	user1 := User{Name: "ScanUser1", Age: 1}
 	user2 := User{Name: "ScanUser2", Age: 10}
@@ -156,3 +161,34 @@ func TestScanRows(t *testing.T) {
 		t.Fatalf("failed to scan ages, got error %v, ages: %v", err, name)
 	}
 }
+
+func TestScanToEmbedded(t *testing.T) {
+	person1 := Person{Name: "person 1"}
+	person2 := Person{Name: "person 2"}
+	DB.Save(&person1).Save(&person2)
+
+	address1 := Address{Name: "address 1"}
+	address2 := Address{Name: "address 2"}
+	DB.Save(&address1).Save(&address2)
+
+	DB.Create(&PersonAddress{PersonID: person1.ID, AddressID: int(address1.ID)})
+	DB.Create(&PersonAddress{PersonID: person1.ID, AddressID: int(address2.ID)})
+	DB.Create(&PersonAddress{PersonID: person2.ID, AddressID: int(address1.ID)})
+
+	var personAddressInfoList []*PersonAddressInfo
+	if err := DB.Select("people.*, addresses.*").
+		Table("people").
+		Joins("inner join person_addresses on people.id = person_addresses.person_id").
+		Joins("inner join addresses on person_addresses.address_id = addresses.id").
+		Find(&personAddressInfoList).Error; err != nil {
+		t.Errorf("Failed to run join query, got error: %v", err)
+	}
+
+	for _, info := range personAddressInfoList {
+		if info.Person != nil {
+			if info.Person.ID == person1.ID && info.Person.Name != person1.Name {
+				t.Errorf("Failed, expected %v, got %v", person1.Name, info.Person.Name)
+			}
+		}
+	}
+}