feat: go code style adjust and optimize code for callbacks package (#4861)

* feat: go code style adjust and optimize code for callbacks package

* Update scan.go

callbacks/associations.go

@@ -39,7 +39,8 @@ func SaveBeforeAssociations(create bool) func(db *gorm.DB) {
 				switch db.Statement.ReflectValue.Kind() {
 				case reflect.Slice, reflect.Array:
 					var (
-						objs      = make([]reflect.Value, 0, db.Statement.ReflectValue.Len())
+						rValLen   = db.Statement.ReflectValue.Len()
+						objs      = make([]reflect.Value, 0, rValLen)
 						fieldType = rel.Field.FieldType
 						isPtr     = fieldType.Kind() == reflect.Ptr
 					)
@@ -49,10 +50,12 @@ func SaveBeforeAssociations(create bool) func(db *gorm.DB) {
 					}
 
 					elems := reflect.MakeSlice(reflect.SliceOf(fieldType), 0, 10)
-					for i := 0; i < db.Statement.ReflectValue.Len(); i++ {
+					for i := 0; i < rValLen; i++ {
 						obj := db.Statement.ReflectValue.Index(i)
+						if reflect.Indirect(obj).Kind() != reflect.Struct {
+							break
+						}
 
-						if reflect.Indirect(obj).Kind() == reflect.Struct {
 						if _, zero := rel.Field.ValueOf(obj); !zero { // check belongs to relation value
 							rv := rel.Field.ReflectValueOf(obj) // relation reflect value
 							objs = append(objs, obj)
@@ -62,9 +65,6 @@ func SaveBeforeAssociations(create bool) func(db *gorm.DB) {
 								elems = reflect.Append(elems, rv.Addr())
 							}
 						}
-						} else {
-							break
-						}
 					}
 
 					if elems.Len() > 0 {

callbacks/create.go

@@ -200,15 +200,16 @@ func ConvertToCreateValues(stmt *gorm.Statement) (values clause.Values) {
 
 		switch stmt.ReflectValue.Kind() {
 		case reflect.Slice, reflect.Array:
-			stmt.SQL.Grow(stmt.ReflectValue.Len() * 18)
+			rValLen := stmt.ReflectValue.Len()
-			values.Values = make([][]interface{}, stmt.ReflectValue.Len())
+			stmt.SQL.Grow(rValLen * 18)
-			defaultValueFieldsHavingValue := map[*schema.Field][]interface{}{}
+			values.Values = make([][]interface{}, rValLen)
-			if stmt.ReflectValue.Len() == 0 {
+			if rValLen == 0 {
 				stmt.AddError(gorm.ErrEmptySlice)
 				return
 			}
 
-			for i := 0; i < stmt.ReflectValue.Len(); i++ {
+			defaultValueFieldsHavingValue := map[*schema.Field][]interface{}{}
+			for i := 0; i < rValLen; i++ {
 				rv := reflect.Indirect(stmt.ReflectValue.Index(i))
 				if !rv.IsValid() {
 					stmt.AddError(fmt.Errorf("slice data #%v is invalid: %w", i, gorm.ErrInvalidData))
@@ -234,11 +235,11 @@ func ConvertToCreateValues(stmt *gorm.Statement) (values clause.Values) {
 
 				for _, field := range stmt.Schema.FieldsWithDefaultDBValue {
 					if v, ok := selectColumns[field.DBName]; (ok && v) || (!ok && !restricted) {
-						if v, isZero := field.ValueOf(rv); !isZero {
+						if rvOfvalue, isZero := field.ValueOf(rv); !isZero {
 							if len(defaultValueFieldsHavingValue[field]) == 0 {
-								defaultValueFieldsHavingValue[field] = make([]interface{}, stmt.ReflectValue.Len())
+								defaultValueFieldsHavingValue[field] = make([]interface{}, rValLen)
 							}
-							defaultValueFieldsHavingValue[field][i] = v
+							defaultValueFieldsHavingValue[field][i] = rvOfvalue
 						}
 					}
 				}
@@ -274,9 +275,9 @@ func ConvertToCreateValues(stmt *gorm.Statement) (values clause.Values) {
 
 			for _, field := range stmt.Schema.FieldsWithDefaultDBValue {
 				if v, ok := selectColumns[field.DBName]; (ok && v) || (!ok && !restricted) {
-					if v, isZero := field.ValueOf(stmt.ReflectValue); !isZero {
+					if rvOfvalue, isZero := field.ValueOf(stmt.ReflectValue); !isZero {
 						values.Columns = append(values.Columns, clause.Column{Name: field.DBName})
-						values.Values[0] = append(values.Values[0], v)
+						values.Values[0] = append(values.Values[0], rvOfvalue)
 					}
 				}
 			}

callbacks/delete.go

@@ -156,16 +156,19 @@ func Delete(config *Config) func(db *gorm.DB) {
 		}
 
 		if !db.DryRun && db.Error == nil {
-			if ok, mode := hasReturning(db, supportReturning); ok {
+			ok, mode := hasReturning(db, supportReturning)
-				if rows, err := db.Statement.ConnPool.QueryContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...); db.AddError(err) == nil {
+			if !ok {
-					gorm.Scan(rows, db, mode)
-					rows.Close()
-				}
-			} else {
 				result, err := db.Statement.ConnPool.ExecContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...)
 				if db.AddError(err) == nil {
 					db.RowsAffected, _ = result.RowsAffected()
 				}
+
+				return
+			}
+
+			if rows, err := db.Statement.ConnPool.QueryContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...); db.AddError(err) == nil {
+				gorm.Scan(rows, db, mode)
+				rows.Close()
 			}
 		}
 	}

callbacks/preload.go

@@ -61,12 +61,13 @@ func preload(db *gorm.DB, rel *schema.Relationship, conds []interface{}, preload
 		fieldValues := make([]interface{}, len(joinForeignFields))
 		joinFieldValues := make([]interface{}, len(joinRelForeignFields))
 		for i := 0; i < joinResults.Len(); i++ {
+			joinIndexValue := joinResults.Index(i)
 			for idx, field := range joinForeignFields {
-				fieldValues[idx], _ = field.ValueOf(joinResults.Index(i))
+				fieldValues[idx], _ = field.ValueOf(joinIndexValue)
 			}
 
 			for idx, field := range joinRelForeignFields {
-				joinFieldValues[idx], _ = field.ValueOf(joinResults.Index(i))
+				joinFieldValues[idx], _ = field.ValueOf(joinIndexValue)
 			}
 
 			if results, ok := joinIdentityMap[utils.ToStringKey(fieldValues...)]; ok {

callbacks/raw.go

@@ -9,8 +9,9 @@ func RawExec(db *gorm.DB) {
 		result, err := db.Statement.ConnPool.ExecContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...)
 		if err != nil {
 			db.AddError(err)
-		} else {
+			return
+		}
+
 		db.RowsAffected, _ = result.RowsAffected()
 	}
-	}
 }

callbacks/row.go

@@ -7,8 +7,10 @@ import (
 func RowQuery(db *gorm.DB) {
 	if db.Error == nil {
 		BuildQuerySQL(db)
+		if db.DryRun {
+			return
+		}
 
-		if !db.DryRun {
 		if isRows, ok := db.Get("rows"); ok && isRows.(bool) {
 			db.Statement.Settings.Delete("rows")
 			db.Statement.Dest, db.Error = db.Statement.ConnPool.QueryContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...)
@@ -18,5 +20,4 @@ func RowQuery(db *gorm.DB) {
 
 		db.RowsAffected = -1
 	}
-	}
 }

callbacks/transaction.go

@@ -20,11 +20,12 @@ func BeginTransaction(db *gorm.DB) {
 func CommitOrRollbackTransaction(db *gorm.DB) {
 	if !db.Config.SkipDefaultTransaction {
 		if _, ok := db.InstanceGet("gorm:started_transaction"); ok {
-			if db.Error == nil {
+			if db.Error != nil {
-				db.Commit()
-			} else {
 				db.Rollback()
+			} else {
+				db.Commit()
 			}
+
 			db.Statement.ConnPool = db.ConnPool
 		}
 	}

callbacks/update.go

@@ -157,7 +157,7 @@ func ConvertToAssignments(stmt *gorm.Statement) (set clause.Set) {
 		case reflect.Slice, reflect.Array:
 			if size := stmt.ReflectValue.Len(); size > 0 {
 				var primaryKeyExprs []clause.Expression
-				for i := 0; i < stmt.ReflectValue.Len(); i++ {
+				for i := 0; i < size; i++ {
 					var exprs = make([]clause.Expression, len(stmt.Schema.PrimaryFields))
 					var notZero bool
 					for idx, field := range stmt.Schema.PrimaryFields {

migrator/migrator.go

@@ -156,7 +156,9 @@ func (m Migrator) AutoMigrate(values ...interface{}) error {
 }
 
 func (m Migrator) GetTables() (tableList []string, err error) {
-	return tableList, m.DB.Raw("SELECT TABLE_NAME FROM information_schema.tables where TABLE_SCHEMA=?", m.CurrentDatabase()).Scan(&tableList).Error
+	err = m.DB.Raw("SELECT TABLE_NAME FROM information_schema.tables where TABLE_SCHEMA=?", m.CurrentDatabase()).
+		Scan(&tableList).Error
+	return
 }
 
 func (m Migrator) CreateTable(values ...interface{}) error {

scan.go

@@ -102,9 +102,9 @@ func (db *DB) scanIntoStruct(sch *schema.Schema, rows *sql.Rows, reflectValue re
 type ScanMode uint8
 
 const (
-	ScanInitialized         ScanMode = 1 << 0
+	ScanInitialized         ScanMode = 1 << 0    // 1
-	ScanUpdate                       = 1 << 1
+	ScanUpdate              ScanMode = 1 << 1    // 2
-	ScanOnConflictDoNothing          = 1 << 2
+	ScanOnConflictDoNothing ScanMode = 1 << 2    // 4
 )
 
 func Scan(rows *sql.Rows, db *DB, mode ScanMode) {