asp.net mvc 5 get related data from different tables

Question

I'm trying to get specific data from different tables based on some requirements, The program is supposed to take some columns of choosing from tables: Contatti, Contacts and Companies which are at different locations and bring them together.

Contact is connected to Companies through CompanyID

What i want is to display the company name basing on the CompanyID field in Contact table. The problem is that i iterate through a list to get the data in the view, and because of that i can't seem to get a company name based on the company ID attribute which is the Contact Foreign Key to the Companies table, what i get is all the companies names, because they're in the same list.

I'm sure there is an easy way to do this but this is a new world for me, thank you for any help.

Contact Model:

public class Contact
{
[Key]
public int ContactId { get; set; }
public string Name { get; set; }
public string Address { get; set; }
public string City { get; set; }
public string State { get; set; }
public string Zip { get; set; }
[DataType(DataType.EmailAddress)]
public string Email { get; set; }
[ForeignKey("Companies")]
public int CompanyId { get; set; }
public virtual ICollection<Companies> Companies { get; set; }
[Required]
//public virtual Contatti Contatti { get; set; }
public virtual ICollection<Contatti> Contatti { get; set; }
}

Companies model:

public class Companies
{
[Key]
public int CompanyId { get; set; }
public string CompanyName { get; set; }
public string CompanyAddress { get; set; }
public string CompanyCity { get; set; }
public string CompanyState { get; set; }
public string CompanyZip { get; set; }
public string CompanyArea { get; set; }
}

Controller:

public ActionResult Index(String Page)
    {

        ContactsUni2 CU = new ContactsUni2();
        CU.Contattis = db2.Contatti.ToList();
        CU.Contacts = db.Contacts.ToList();
        CU.Companies = db.Companies.ToList();
        List<ContactsUni2> contactlist = new List<ContactsUni2>();
        contactlist.Add(CU);
        return View(contactlist);
    }

View:

    @foreach (var item in Model)
    {
        for (int i = 0; i < item.Contacts.Count; i++)
        {
            <tr>
                <td>
                    @item.Contacts[i].ContactId
                </td>
                <td>
                    @item.Contacts[i].Name
                </td>
                <td>
                    @item.Contacts[i].Address
                </td>
                <td>
                    @item.Contacts[i].CompanyId
                </td>
                    @if (@item.Contacts[i].CompanyId == item.Companies[i].CompanyId)
                        {
                    <td>
                        @item.Companies[i].CompanyName
                    </td>
                    <td>
                        @item.Companies[i].CompanyCity
                    </td>
                    <td>
                        @item.Companies[i].CompanyArea
                    </td>
                        }
                    }
                </tr>
                <tr>
                    <td>
                        @item.Contattis[i].ContattoID
                    </td>
                    <td>
                        @item.Contattis[i].Nome
                    </td>
                    <td>
                        @item.Contattis[i].Citta
                    </td>
                    <td>
                        @item.Contattis[i].CodicePostale
                    </td>
                    <td>
                        @item.Contattis[i].Email
                    </td>
            </tr>


        }
    }

</table>

</body>
</html>

Answer 1

You can try populating the company collection for each of your contacts and then fix the view to access its own member directly instead of looking for it in the Companies list.

public ActionResult Index(String Page)
{

    ContactsUni2 CU = new ContactsUni2();
    CU.Contattis = db2.Contatti.ToList();
    CU.Contacts = db.Contacts.ToList();
    CU.Companies = db.Companies.ToList();

    foreach(var contact in CU.Contacts)
    {
        contact.Companies = CU.Companies
                          .Where(com => com.CompanyId == contact.CompanyId)
                          .ToList();
    }

    List<ContactsUni2> contactlist = new List<ContactsUni2>();
    contactlist.Add(CU);
    return View(contactlist);
}

In the view, you can replace:

@if (@item.Contacts[i].CompanyId == item.Companies[i].CompanyId)
{
  <td>
   @item.Companies[i].CompanyName
 </td>
 <td>
   @item.Companies[i].CompanyCity
 </td>
 <td>
   @item.Companies[i].CompanyArea
 </td>
}

With something like this: (Notice that the if statement is removed)

<td>
   @item.Contacts[i].Companies[0].CompanyName
</td>
<td>
   @item.Contacts[i].Companies[0].CompanyCity
</td>
<td>
   @item.Contacts[i].Companies[0].CompanyArea
</td>

EDIT: Since ICollection does not support indexes, the companies collection should be changed from

public virtual ICollection<Companies> Companies { get; set; }

to

public virtual IList<Companies> Companies { get; set; }

Or any other type of collection supporting indexes.