analysis mysql conn string for get charset. set charset when use Sync()

hi,i'm using xorm.and i found when i sync table(create it).
the table is not support chinese word yet .
Even though open db like this : root:<password>@tcp(<ip>:3306)/crawler?charset=utf8
and i found CharSet() method in session.go and statement.go
but i can't find it in engine
so,i don't konw how to use it.
and i commit this to support chinese word