@using (Html.BeginForm("", "actionname", FormMethod.Post, new { id = "card-activate-form" , data_parsley_validate="true" }))
will render
<form action="actionname" data-parsley-validate="true" id="card-activate-form" method="post">
but ideally it should be 'data-parsley-validate' only
<form action="actionname" data-parsley-validate id="card-activate-form" method="post">
how to add data-parsley-validate only in the form