field: models.SysUserBean.Username, unsupport field type &{{ %!s(bool=false)}}, may be miss setting tag

[dishuiya]

I use beego with "nuu.v4", create struct

type SysUserBean struct { UserId int64 orm:"auto" json:"userId" Username null.String json:"username" }

when run "bee run", then tips, "field: models.SysUserBean.Username, unsupport field type &{{ %!s(bool=false)}}, may be miss setting tag", can't go on

how to fix it