How to Linq query against combobox using c#

Question

I have a simple question that is driving me mad. I am trying to query a data entity and everything works until I try to reference something external. In the code below (which works perfectly) I want to change the .where clientID == 15 to .where the client ID is the value shown in a combobox, the combobox valuemember is an integer:

 private void cboxcos_SelectionChangeCommitted(object sender, EventArgs e)
    {
        using (var context2 = new tvdm())
        {
            var cus = context2.tblContacts
                .Where(c => c.ClientID == 15)
               .Select(c => new {c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
                .OrderBy(p => p.LastName)
                .ToList();

            dataGridView1.DataSource = cus;               

        }
    }

Any simple help would be greatly appreciated.

I am using VS2015 Community with C# and EF6

Answer 1

Get the value first, cast it to the correct type and then use that parameter in the linq query:

    private void cboxcos_SelectionChangeCommitted(object sender, EventArgs e)
    {
        int value = (int)comboBox1.SelectedValue;
        using (var context2 = new tvdm())
        {
            var cus = context2.tblContacts
                .Where(c => c.ClientID == value)
               .Select(c => new { c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
                .OrderBy(p => p.LastName)
                .ToList();

            dataGridView1.DataSource = cus;

        }
    }

Answer 2

I suppose you need something like

var cus = context2.tblContacts
    .Where(c => c.ClientID == Convert.ToInt32(myComboBox.SelectedItem))
    .Select(c => new {c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
    .OrderBy(p => p.LastName)
    .ToList();

Answer 3

private void comboBox1_SelectionChangeCommitted(object sender, EventArgs e)
{

ComboBox senderComboBox = (ComboBox) sender;
int selectedValue = (int)senderComboBox.SelectedValue;

// and assuming that there's nothing wrong with this code
using (var context2 = new tvdm())
    {
        var cus = context2.tblContacts
            .Where(c => c.ClientID == selectedValue)
           .Select(c => new { c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
            .OrderBy(p => p.LastName)
            .ToList();

        dataGridView1.DataSource = cus;

    }

}

Answer 4

I actually ended up with:

private void cboxcos_SelectionChangeCommitted(object sender, EventArgs e)
    {
        using (var context2 = new tvdm())
        {
            int value = (int)cboxcos.SelectedValue;
            var cus = context2.tblContacts
                .Where(c => c.ClientID == value)
               .Select(c => new {c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
                .OrderBy(p => p.LastName)
                .ToList();

            dataGridView1.DataSource = cus;               

        }
    }