Insert Data Into My DB trouble - asp.net-mvc

Question

This is the View code, this view will show a list of preInscription Demande and two button Valide and Delete the first one it allow Webmaster To Inscription and the seconde one to Refuse Demande.
<%# Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<J2V.Models.preinscrit>>" %>
// some Html Code
<% foreach (var item in Model) { %>
<li>
<div class="listinfo">
<h3>
<%: Html.DisplayFor(modelItem => item.Nag) %>
</h3>
<p>
<%: Html.DisplayFor(modelItem => item.Idag) %>
</p>
<span class="price"> <%: Html.DisplayFor(modelItem => item.Adrag) %> <%: Html.DisplayFor(modelItem => item.Vilag) %> <%: Html.DisplayFor(modelItem => item.Gov) %></span> <span class="media">Tel : <%: Html.DisplayFor(modelItem => item.Telag) %> |</span> <%: Html.DisplayFor(modelItem => item.Mailag) %>
</div>
<div class="listingbtns">
<span class="listbuttons"><%: Html.ActionLink("Valide", "Valide", new {mod= item}) %> |</span>
<span class="listbuttons"><%: Html.ActionLink("Supprime", "Delete", new { id=item.Idag }) %></span>
</div>
<div class="clear">
</div>
</li>
<% } %>
This is the "Valide" Action it allow To Validate preinscription and add Data to Agence Table and user table:
[HttpGet]
public ActionResult Valide(Models.preinscrit model )
{
var db = new Models.J2VEntities();
Models.agence ag = new Models.agence();
Models.user user = new Models.user();
ag.Adrag = model.Adrag ;
ag.Gov = model.Gov ;
ag.Idag = model.Idag;
ag.Mailag = model.Mailag;
ag.Nomag = model.Nag;
ag.Vilag = model.Vilag;
user.IsAdmin = false;
user.iduser = model.Idag;
user.password = Models.LogModel.register.CreateRandomPassword();
db.AddTouser(user);
db.AddToagence(ag);
return View("index");
}
When I click on Valide on my view page I get this error :
System.NullReferenceException
at this line ag.Adrag = model.Adrag ;

Answer 1

no need to use form. use actionlink to send item.id.
<span class="listbuttons"><%: Html.ActionLink("Valide", "Valide", new {id= item.id}) %> |</span>
and get id in valide action and get the model in your database by item.id
public ActionResult Valide(int id )
{
var db = new Models.J2VEntities();
Models.agence ag = new Models.agence();
Models.user user = new Models.user();
//select from databese by id and valide
ag.Adrag = model.Adrag ;
ag.Gov = model.Gov ;
ag.Idag = model.Idag;
ag.Mailag = model.Mailag;
ag.Nomag = model.Nag;
ag.Vilag = model.Vilag;
user.IsAdmin = false;
user.iduser = model.Idag;
user.password = Models.LogModel.register.CreateRandomPassword();
db.AddTouser(user);
db.AddToagence(ag);
return View("index");
}
this code is from my project :
//select list by id
public IEnumerable<makale> select_makaleler_by_kategori(int kategori_id)
{
IEnumerable<makale> makale = (from m in entity.makale
where m.kategori_id == kategori_id
orderby m.olusturma_tarihi
select m).ToList<makale>();
return makale;
}
//select one element by id
public makale select_makale(int makale_id)
{
makale makale = (from m in entity.makale
where m.makale_id == makale_id
select m).SingleOrDefault();
return makale;
}

Answer 2

you are using ActionLink for the wrong reason , it isn't used for passing data , you should make a <form> and then submit it using <input type='submit' />
the problem happens because the 3rd parameter in the ActionLink() is the routing values that works with the routing rules , its not used for sending data
from the code sample i think the user didnt enter anything the view just for showing the page
if that is the case then just pass an id to the ActionLink and in the Controller action query again all the information from the database using the id
never depend on passing parameter used for showing purpose from page to page , a hacker can easily break your app
so if you dont want information from the user just pass the id then query again in the other page