Merge pull request #49 from mtsoltan/fix-scan-value

Fix option to handle type conversion

.gitignore

@@ -34,3 +34,4 @@ go.work
 cover.out
 cover.html
 .vscode
+.idea

option.go

@@ -297,7 +297,7 @@ func (o *Option[T]) Scan(src any) error {
 		}
 	}
 
-	return fmt.Errorf("failed to scan Option[T]")
+	return o.scanConvertValue(src)
 }
 
 // Value implements the driver Valuer interface.
@@ -306,7 +306,7 @@ func (o Option[T]) Value() (driver.Value, error) {
 		return nil, nil
 	}
 
-	return o.value, nil
+	return driver.DefaultParameterConverter.ConvertValue(o.value)
 }
 
 // leftValue returns an error if the Option is None, otherwise nil

option_go118.go

@@ -0,0 +1,327 @@
+//go:build !go1.22
+// +build !go1.22
+
+package mo
+
+//
+// sql.Null[T] has been introduce in go1.22
+// This file is a copy of stdlib and ensure retro-compatibility.
+// See https://github.com/samber/mo/pull/49
+//
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"errors"
+	"fmt"
+	"reflect"
+	"strconv"
+	"time"
+)
+
+var errNilPtr = errors.New("destination pointer is nil")
+
+func cloneBytes(b []byte) []byte {
+	if b == nil {
+		return nil
+	}
+	c := make([]byte, len(b))
+	copy(c, b)
+	return c
+}
+
+func asString(src any) string {
+	switch v := src.(type) {
+	case string:
+		return v
+	case []byte:
+		return string(v)
+	}
+	rv := reflect.ValueOf(src)
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return strconv.FormatInt(rv.Int(), 10)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return strconv.FormatUint(rv.Uint(), 10)
+	case reflect.Float64:
+		return strconv.FormatFloat(rv.Float(), 'g', -1, 64)
+	case reflect.Float32:
+		return strconv.FormatFloat(rv.Float(), 'g', -1, 32)
+	case reflect.Bool:
+		return strconv.FormatBool(rv.Bool())
+	}
+	return fmt.Sprintf("%v", src)
+}
+
+func asBytes(buf []byte, rv reflect.Value) (b []byte, ok bool) {
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return strconv.AppendInt(buf, rv.Int(), 10), true
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return strconv.AppendUint(buf, rv.Uint(), 10), true
+	case reflect.Float32:
+		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 32), true
+	case reflect.Float64:
+		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 64), true
+	case reflect.Bool:
+		return strconv.AppendBool(buf, rv.Bool()), true
+	case reflect.String:
+		s := rv.String()
+		return append(buf, s...), true
+	}
+	return
+}
+
+func strconvErr(err error) error {
+	if ne, ok := err.(*strconv.NumError); ok {
+		return ne.Err
+	}
+	return err
+}
+
+// convertAssignRows copies to dest the value in src, converting it if possible.
+// An error is returned if the copy would result in loss of information.
+// dest should be a pointer type. If rows is passed in, the rows will
+// be used as the parent for any cursor values converted from a
+// driver.Rows to a *Rows.
+func convertAssign(dest, src any) error {
+	// Common cases, without reflect.
+	switch s := src.(type) {
+	case string:
+		switch d := dest.(type) {
+		case *string:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = s
+			return nil
+		case *[]byte:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = []byte(s)
+			return nil
+		case *sql.RawBytes:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = append((*d)[:0], s...)
+			return nil
+		}
+	case []byte:
+		switch d := dest.(type) {
+		case *string:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = string(s)
+			return nil
+		case *any:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = cloneBytes(s)
+			return nil
+		case *[]byte:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = cloneBytes(s)
+			return nil
+		case *sql.RawBytes:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = s
+			return nil
+		}
+	case time.Time:
+		switch d := dest.(type) {
+		case *time.Time:
+			*d = s
+			return nil
+		case *string:
+			*d = s.Format(time.RFC3339Nano)
+			return nil
+		case *[]byte:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = []byte(s.Format(time.RFC3339Nano))
+			return nil
+		case *sql.RawBytes:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = s.AppendFormat((*d)[:0], time.RFC3339Nano)
+			return nil
+		}
+	case nil:
+		switch d := dest.(type) {
+		case *any:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = nil
+			return nil
+		case *[]byte:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = nil
+			return nil
+		case *sql.RawBytes:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = nil
+			return nil
+		}
+	}
+
+	var sv reflect.Value
+
+	switch d := dest.(type) {
+	case *string:
+		sv = reflect.ValueOf(src)
+		switch sv.Kind() {
+		case reflect.Bool,
+			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
+			reflect.Float32, reflect.Float64:
+			*d = asString(src)
+			return nil
+		}
+	case *[]byte:
+		sv = reflect.ValueOf(src)
+		if b, ok := asBytes(nil, sv); ok {
+			*d = b
+			return nil
+		}
+	case *sql.RawBytes:
+		sv = reflect.ValueOf(src)
+		if b, ok := asBytes([]byte(*d)[:0], sv); ok {
+			*d = sql.RawBytes(b)
+			return nil
+		}
+	case *bool:
+		bv, err := driver.Bool.ConvertValue(src)
+		if err == nil {
+			*d = bv.(bool)
+		}
+		return err
+	case *any:
+		*d = src
+		return nil
+	}
+
+	if scanner, ok := dest.(sql.Scanner); ok {
+		return scanner.Scan(src)
+	}
+
+	dpv := reflect.ValueOf(dest)
+	if dpv.Kind() != reflect.Pointer {
+		return errors.New("destination not a pointer")
+	}
+	if dpv.IsNil() {
+		return errNilPtr
+	}
+
+	if !sv.IsValid() {
+		sv = reflect.ValueOf(src)
+	}
+
+	dv := reflect.Indirect(dpv)
+	if sv.IsValid() && sv.Type().AssignableTo(dv.Type()) {
+		switch b := src.(type) {
+		case []byte:
+			dv.Set(reflect.ValueOf(cloneBytes(b)))
+		default:
+			dv.Set(sv)
+		}
+		return nil
+	}
+
+	if dv.Kind() == sv.Kind() && sv.Type().ConvertibleTo(dv.Type()) {
+		dv.Set(sv.Convert(dv.Type()))
+		return nil
+	}
+
+	// The following conversions use a string value as an intermediate representation
+	// to convert between various numeric types.
+	//
+	// This also allows scanning into user defined types such as "type Int int64".
+	// For symmetry, also check for string destination types.
+	switch dv.Kind() {
+	case reflect.Pointer:
+		if src == nil {
+			dv.Set(reflect.Zero(dv.Type()))
+			return nil
+		}
+		dv.Set(reflect.New(dv.Type().Elem()))
+		return convertAssign(dv.Interface(), src)
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		if src == nil {
+			return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
+		}
+		s := asString(src)
+		i64, err := strconv.ParseInt(s, 10, dv.Type().Bits())
+		if err != nil {
+			err = strconvErr(err)
+			return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
+		}
+		dv.SetInt(i64)
+		return nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		if src == nil {
+			return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
+		}
+		s := asString(src)
+		u64, err := strconv.ParseUint(s, 10, dv.Type().Bits())
+		if err != nil {
+			err = strconvErr(err)
+			return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
+		}
+		dv.SetUint(u64)
+		return nil
+	case reflect.Float32, reflect.Float64:
+		if src == nil {
+			return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
+		}
+		s := asString(src)
+		f64, err := strconv.ParseFloat(s, dv.Type().Bits())
+		if err != nil {
+			err = strconvErr(err)
+			return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
+		}
+		dv.SetFloat(f64)
+		return nil
+	case reflect.String:
+		if src == nil {
+			return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
+		}
+		switch v := src.(type) {
+		case string:
+			dv.SetString(v)
+			return nil
+		case []byte:
+			dv.SetString(string(v))
+			return nil
+		}
+	}
+
+	return fmt.Errorf("unsupported Scan, storing driver.Value type %T into type %T", src, dest)
+}
+
+func (o *Option[T]) scanConvertValue(src any) error {
+	// we try to convertAssign values that we can't directly assign because ConvertValue
+	// will return immediately for v that is already a Value, even if it is a different
+	// Value type than the one we expect here.
+	var dest T
+	if err := convertAssign(&dest, src); err == nil {
+		o.isPresent = true
+		o.value = dest
+		return nil
+	}
+	return fmt.Errorf("failed to scan Option[T]")
+}

option_go122.go

@@ -0,0 +1,22 @@
+//go:build go1.22
+// +build go1.22
+
+package mo
+
+import (
+	"database/sql"
+	"fmt"
+)
+
+func (o *Option[T]) scanConvertValue(src any) error {
+	// we try to convertAssign values that we can't directly assign because ConvertValue
+	// will return immediately for v that is already a Value, even if it is a different
+	// Value type than the one we expect here.
+	var st sql.Null[T]
+	if err := st.Scan(src); err == nil {
+		o.isPresent = true
+		o.value = st.V
+		return nil
+	}
+	return fmt.Errorf("failed to scan Option[T]")
+}