Optimize reflect value length and method (#4280)

* Respect ignore migration when add column (#4276)

continue https://github.com/go-gorm/gorm/pull/4028

* feat: Optimal value type acquisition for v (#4278)

* feat: optimize relect value length and value

* feat: optimize ConvertSliceOfMapToValuesForCreate method

Co-authored-by: yrong1997 <yrong1997@gmail.com>

callbacks/associations.go

@@ -288,12 +288,13 @@ func SaveAfterAssociations(create bool) func(db *gorm.DB) {
 					appendToElems(db.Statement.ReflectValue)
 				}
 
-				if elems.Len() > 0 {
+				// optimize elems of reflect value length
+				if elemLen := elems.Len(); elemLen > 0 {
 					if v, ok := selectColumns[rel.Name+".*"]; !ok || v {
 						saveAssociations(db, rel, elems.Interface(), selectColumns, restricted, nil)
 					}
 
-					for i := 0; i < elems.Len(); i++ {
+					for i := 0; i < elemLen; i++ {
 						appendToJoins(objs[i], elems.Index(i))
 					}
 				}

callbacks/helper.go

@@ -42,15 +42,20 @@ func ConvertMapToValuesForCreate(stmt *gorm.Statement, mapValue map[string]inter
 func ConvertSliceOfMapToValuesForCreate(stmt *gorm.Statement, mapValues []map[string]interface{}) (values clause.Values) {
 	var (
 		columns = make([]string, 0, len(mapValues))
-		result                    = map[string][]interface{}{}
-		selectColumns, restricted = stmt.SelectAndOmitColumns(true, false)
 	)
 
+	// when the length of mapValues,return directly here
+	// no need to call stmt.SelectAndOmitColumns method
 	if len(mapValues) == 0 {
 		stmt.AddError(gorm.ErrEmptySlice)
 		return
 	}
 
+	var (
+		result                    = make(map[string][]interface{}, len(mapValues))
+		selectColumns, restricted = stmt.SelectAndOmitColumns(true, false)
+	)
+
 	for idx, mapValue := range mapValues {
 		for k, v := range mapValue {
 			if stmt.Schema != nil {

schema/utils.go

@@ -71,10 +71,10 @@ func GetRelationsValues(reflectValue reflect.Value, rels []*Relationship) (refle
 					reflectResults = reflect.Append(reflectResults, result.Addr())
 				case reflect.Slice, reflect.Array:
 					for i := 0; i < result.Len(); i++ {
-						if result.Index(i).Kind() == reflect.Ptr {
+						if elem := result.Index(i); elem.Kind() == reflect.Ptr {
-							reflectResults = reflect.Append(reflectResults, result.Index(i))
+							reflectResults = reflect.Append(reflectResults, elem)
 						} else {
-							reflectResults = reflect.Append(reflectResults, result.Index(i).Addr())
+							reflectResults = reflect.Append(reflectResults, elem.Addr())
 						}
 					}
 				}

statement.go

@@ -328,8 +328,10 @@ func (stmt *Statement) BuildCondition(query interface{}, args ...interface{}) []
 					} else if _, ok := v[key].(Valuer); ok {
 						conds = append(conds, clause.Eq{Column: key, Value: v[key]})
 					} else {
-						values := make([]interface{}, reflectValue.Len())
+						// optimize relect value length
-						for i := 0; i < reflectValue.Len(); i++ {
+						valueLen := reflectValue.Len()
+						values := make([]interface{}, valueLen)
+						for i := 0; i < valueLen; i++ {
 							values[i] = reflectValue.Index(i).Interface()
 						}
 
@@ -396,8 +398,10 @@ func (stmt *Statement) BuildCondition(query interface{}, args ...interface{}) []
 				if len(args) == 1 {
 					switch reflectValue.Kind() {
 					case reflect.Slice, reflect.Array:
-						values := make([]interface{}, reflectValue.Len())
+						// optimize relect value length
-						for i := 0; i < reflectValue.Len(); i++ {
+						valueLen := reflectValue.Len()
+						values := make([]interface{}, valueLen)
+						for i := 0; i < valueLen; i++ {
 							values[i] = reflectValue.Index(i).Interface()
 						}