如何在onsave中修改要保存的结果

[HWTsang]

editable={{
type: 'multiple',
editableKeys,
onSave: async (key, newRow, row) => {
const tmp = omit(newRow, 'id', 'exist', 'index');
for (const key in tmp) {
if (tmp[key] === '') {
tmp[key] = undefined;
}
}
if (row.exist) {}
else {row.exist=true}
}}

怎么实现这段逻辑
if (row.exist) {}
else {row.exist=true}
修改一个字段