CODEWITHSUNDEEP
c#
saeed
saeed

Reputation: 673

Item of one combobox should not come into the other

Im using c# .net windows form application. I have a database with some tables.I have two comboboxes (A & B). I have populated a combo box A with column names of a table using sys.columns. Now when i select an item in combo box A ,combo box B should be populated with the same items except the selected item which was selected in combobox A .

Upvotes: 0

Views: 217

Answers (4)

code4life
code4life

Reputation: 15794

I'd use a combination of static extension methods and LINQ.

The static extension part would look like this:

// static class...
public static class ComboBoxHelper
{
    public static string GetSelectedIndexText(this ComboBox target)
    {
        return target.Items[target.SelectedIndex].ToString();
    }

    public static object[] GetNonSelectedItems(this ComboBox target)
    {
        string selected = GetSelectedIndexText(target);

        try
        {
            object[] result = 
              target.Items.Cast<object>().Where(c => c.ToString() 
              != selected).ToArray();
            return result;
        }
        catch
        {
            return new object[] { };
        }
    }

    public static void ReplaceItems(this ComboBox target, object[] newRange)
    {
        target.Items.Clear();
        target.Items.AddRange(newRange);
    }
}

And the LINQ:

// LINQ:
private void ComboBoxA_SelectedIndexChanged(object sender, EventArgs e)
{
    comboBoxB.ReplaceItems(comboBoxA.GetNonSelectedItems());
}

HTH!

Note: there's probably more efficient way than returning an array of list items, but I haven't found this to be a big issue in terms of the big picture (e.g. overall performance, etc).....

Upvotes: 1

Patrik Svensson
Patrik Svensson

Reputation: 13844

m_comboB.Items.AddRange((from item in m_comboA.Items.Cast<object>() 
                         where item != m_comboA.SelectedItem 
                         select item).ToArray());

Or you can use this way which don't remove duplicate items (Sam pointed this out in his comment):

m_comboB.Items.AddRange(Enumerable.Range(0, m_comboA.Items.Count)
    .Where(index => index != m_comboA.SelectedIndex)
    .Select(index => m_comboA.Items[index]).ToArray());

Upvotes: 0

Daniel Dolz
Daniel Dolz

Reputation: 2421

I think you will have to code the filling/removal of B in the Change Event of A

Upvotes: 0

Sam Holder
Sam Holder

Reputation: 32936

You should delete either this question or this one which are about identical things. anyway, here is my identical answer:

in the selected item changed event of A, add code which clears B, then loops round each item in A's Item collection and adds it to B as long as the index of the current item is different from the index of the SelectedItem in A.

Something like (pseudo code, not tested)

b.Items.Clear;
for(int i=0; i<A.Items.Count; i++)
{
    if (i!=A.SelectedItemIndex)
    {
    b.Items.Add(A.Items[i]);
    } 
}

or 

B.Items.Clear;
foreach(object o in A.Items)
{
     b.Items.Add(o);
}
b.Items.Remove(A.SelectedItem);

should do it as well.

Upvotes: 1

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