public async Task EditRoleIds(long userId, long[] roleIds)
{
using (var db = new WeixinDbContext())
{
CommonService <User> userCs = new CommonService <User>(db);
var user = await userCs.GetById(userId);
if (user == null)
{
throw new ArgumentException("用户不存在" + userId);
}
user.Roles.Clear();//先清空用户的角色
CommonService <Role> roleCs = new CommonService <Role>(db);
//寻找数据库里的roleId和传入的roleId的交集
var roles = await roleCs.GetAll().Where(r => roleIds.Contains(r.Id)).ToArrayAsync();
foreach (var role in roles)
{
user.Roles.Add(role);//重新添加角色
}
await db.SaveChangesAsync();
}
}