dialect/sqlscan: add interface{} scanning support

Summary: Pull Request resolved: https://github.com/facebookincubator/ent/pull/223

Reviewed By: alexsn

Differential Revision: D18878581

fbshipit-source-id: 4a60ceea6c092f065e52e6b3bb625487451a815d

dialect/sql/scan.go

@@ -98,6 +98,8 @@ func (r *rowScan) values() []interface{} {
 // scanType returns rowScan for the given reflect.Type.
 func scanType(typ reflect.Type, columns []string) (*rowScan, error) {
 	switch k := typ.Kind(); {
+	case k == reflect.Interface && typ.NumMethod() == 0:
+		fallthrough // interface{}
 	case k == reflect.String || k >= reflect.Bool && k <= reflect.Float64:
 		return &rowScan{
 			columns: []reflect.Type{typ},

dialect/sql/scan_test.go

@@ -6,6 +6,7 @@ package sql
 
 import (
 	"database/sql"
+	"database/sql/driver"
 	"testing"
 
 	"github.com/DATA-DOG/go-sqlmock"
@@ -139,6 +140,24 @@ func TestScanInt64(t *testing.T) {
 	require.EqualValues(t, 10, n)
 }
 
+func TestInterface(t *testing.T) {
+	mock := sqlmock.NewRows([]string{"age"}).
+		AddRow("10").
+		AddRow("20")
+	var values []driver.Value
+	err := ScanSlice(toRows(mock), &values)
+	require.NoError(t, err)
+	require.Equal(t, []driver.Value{"10", "20"}, values)
+
+	mock = sqlmock.NewRows([]string{"age"}).
+		AddRow(10).
+		AddRow(20)
+	values = values[:0:0]
+	err = ScanSlice(toRows(mock), &values)
+	require.NoError(t, err)
+	require.Equal(t, []driver.Value{int64(10), int64(20)}, values)
+}
+
 func toRows(mrows *sqlmock.Rows) *sql.Rows {
 	db, mock, _ := sqlmock.New()
 	mock.ExpectQuery("").WillReturnRows(mrows)