public function edit(){
$Id=input('Id');
$admins=db('admin')->find($Id);//该方法无法通过Id获取相应的数据
if (request()->isPost()) {
$data=[
'Id'=>input('Id'),
'username'=>input('username'),
//'password'=>input('password'),
];
if (input('password')) {
$data['password']=input('password');
} else {
$data['password']=$admins['password'];
}

if (db('admin')->update($data)) {
$this->success('修改管理员成功','lst');
} else {
$this->success('修改管理员失败');
}
return;
}

$this->assign('admins',$admins);
return $this->fetch();
}