Refactor find (#2031)

Reviewed-on: https://gitea.com/xorm/xorm/pulls/2031
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-committed-by: Lunny Xiao <xiaolunwen@gmail.com>

convert/conversion.go

@@ -325,6 +325,9 @@ func AssignValue(dv reflect.Value, src interface{}) error {
 	if src == nil {
 		return nil
 	}
+	if v, ok := src.(*interface{}); ok {
+		return AssignValue(dv, *v)
+	}
 
 	if dv.Type().Implements(scannerType) {
 		return dv.Interface().(sql.Scanner).Scan(src)

internal/utils/new.go

@@ -0,0 +1,25 @@
+// Copyright 2021 The Xorm Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package utils
+
+import "reflect"
+
+// New creates a value according type
+func New(tp reflect.Type, length, cap int) reflect.Value {
+	switch tp.Kind() {
+	case reflect.Slice:
+		slice := reflect.MakeSlice(tp, length, cap)
+		x := reflect.New(slice.Type())
+		x.Elem().Set(slice)
+		return x
+	case reflect.Map:
+		mp := reflect.MakeMapWithSize(tp, cap)
+		x := reflect.New(mp.Type())
+		x.Elem().Set(mp)
+		return x
+	default:
+		return reflect.New(tp)
+	}
+}

session_find.go

@@ -161,6 +161,16 @@ func (session *Session) find(rowsSlicePtr interface{}, condiBean ...interface{})
 }
 
 func (session *Session) noCacheFind(table *schemas.Table, containerValue reflect.Value, sqlStr string, args ...interface{}) error {
+	elemType := containerValue.Type().Elem()
+	var isPointer bool
+	if elemType.Kind() == reflect.Ptr {
+		isPointer = true
+		elemType = elemType.Elem()
+	}
+	if elemType.Kind() == reflect.Ptr {
+		return errors.New("pointer to pointer is not supported")
+	}
+
 	rows, err := session.queryRows(sqlStr, args...)
 	if err != nil {
 		return err
@@ -177,31 +187,8 @@ func (session *Session) noCacheFind(table *schemas.Table, containerValue reflect
 		return err
 	}
 
-	var newElemFunc func(fields []string) reflect.Value
+	var newElemFunc = func(fields []string) reflect.Value {
-	elemType := containerValue.Type().Elem()
+		return utils.New(elemType, len(fields), len(fields))
-	var isPointer bool
-	if elemType.Kind() == reflect.Ptr {
-		isPointer = true
-		elemType = elemType.Elem()
-	}
-	if elemType.Kind() == reflect.Ptr {
-		return errors.New("pointer to pointer is not supported")
-	}
-
-	newElemFunc = func(fields []string) reflect.Value {
-		switch elemType.Kind() {
-		case reflect.Slice:
-			slice := reflect.MakeSlice(elemType, len(fields), len(fields))
-			x := reflect.New(slice.Type())
-			x.Elem().Set(slice)
-			return x
-		case reflect.Map:
-			mp := reflect.MakeMap(elemType)
-			x := reflect.New(mp.Type())
-			x.Elem().Set(mp)
-			return x
-		}
-		return reflect.New(elemType)
 	}
 
 	var containerValueSetFunc func(*reflect.Value, schemas.PK) error
@@ -226,10 +213,15 @@ func (session *Session) noCacheFind(table *schemas.Table, containerValue reflect
 
 		containerValueSetFunc = func(newValue *reflect.Value, pk schemas.PK) error {
 			keyValue := reflect.New(keyType)
-			err := convertPKToValue(table, keyValue.Interface(), pk)
+			cols := table.PKColumns()
-			if err != nil {
+			if len(cols) == 1 {
+				if err := convert.AssignValue(keyValue, pk[0]); err != nil {
 					return err
 				}
+			} else {
+				keyValue.Set(reflect.ValueOf(&pk))
+			}
+
 			if isPointer {
 				containerValue.SetMapIndex(keyValue.Elem(), newValue.Elem().Addr())
 			} else {
@@ -241,8 +233,7 @@ func (session *Session) noCacheFind(table *schemas.Table, containerValue reflect
 
 	if elemType.Kind() == reflect.Struct {
 		var newValue = newElemFunc(fields)
-		dataStruct := utils.ReflectValue(newValue.Interface())
+		tb, err := session.engine.tagParser.ParseWithCache(newValue)
-		tb, err := session.engine.tagParser.ParseWithCache(dataStruct)
 		if err != nil {
 			return err
 		}
@@ -266,7 +257,6 @@ func (session *Session) noCacheFind(table *schemas.Table, containerValue reflect
 		default:
 			err = rows.Scan(bean)
 		}
-
 		if err != nil {
 			return err
 		}
@@ -278,16 +268,6 @@ func (session *Session) noCacheFind(table *schemas.Table, containerValue reflect
 	return rows.Err()
 }
 
-func convertPKToValue(table *schemas.Table, dst interface{}, pk schemas.PK) error {
-	cols := table.PKColumns()
-	if len(cols) == 1 {
-		return convert.Assign(dst, pk[0], nil, nil)
-	}
-
-	dst = pk
-	return nil
-}
-
 func (session *Session) cacheFind(t reflect.Type, sqlStr string, rowsSlicePtr interface{}, args ...interface{}) (err error) {
 	if !session.canCache() ||
 		utils.IndexNoCase(sqlStr, "having") != -1 ||