add support custom type Nullfloat64 (go-xorm#1450)

Author: lunny

session_convert.go

@@ -84,6 +84,10 @@ func (session *Session) byte2Time(col *core.Column, data []byte) (outTime time.T
 	return session.str2Time(col, string(data))
 }
 
+var (
+	nullFloatType = reflect.TypeOf(sql.NullFloat64{})
+)
+
 // convert a db data([]byte) to a field value
 func (session *Session) bytes2Value(col *core.Column, fieldValue *reflect.Value, data []byte) error {
 	if structConvert, ok := fieldValue.Addr().Interface().(core.Conversion); ok {
@@ -583,6 +587,12 @@ func (session *Session) value2Interface(col *core.Column, fieldValue reflect.Val
 			t := fieldValue.Convert(core.TimeType).Interface().(time.Time)
 			tf := session.engine.formatColTime(col, t)
 			return tf, nil
+		} else if fieldType.ConvertibleTo(nullFloatType) {
+			t := fieldValue.Convert(nullFloatType).Interface().(sql.NullFloat64)
+			if !t.Valid {
+				return nil, nil
+			}
+			return t.Float64, nil
 		}
 
 		if !col.SQLType.IsJson() {

session_test.go

@@ -5,6 +5,7 @@
 package xorm
 
 import (
+	"database/sql"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -21,3 +22,24 @@ func TestClose(t *testing.T) {
 	sess2.Close()
 	assert.True(t, sess2.IsClosed())
 }
+
+func TestNullFloatStruct(t *testing.T) {
+	type MyNullFloat64 sql.NullFloat64
+
+	type MyNullFloatStruct struct {
+		Uuid   string
+		Amount MyNullFloat64
+	}
+
+	assert.NoError(t, prepareEngine())
+	assert.NoError(t, testEngine.Sync2(new(MyNullFloatStruct)))
+
+	_, err := testEngine.Insert(&MyNullFloatStruct{
+		Uuid: "111111",
+		Amount: MyNullFloat64(sql.NullFloat64{
+			Float64: 0.1111,
+			Valid:   true,
+		}),
+	})
+	assert.NoError(t, err)
+}