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C# combobox drop down

Posted on 2004-08-03
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Last Modified: 2010-04-15
Hello Expert,
I was am programming a c# windows form and on it i have a comobox populated with Cities. The combo box is populated from a database I set the type of box to dropdown because I want to be able to as the user types in letters for it to narrow down to the city in the combobox and if it is not there I want to be able to add the newly typed city to the database. Is this possible?
Thanks
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Question by:jvoros1
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8 Comments
 
LVL 25

Expert Comment

by:nauman_ahmed
ID: 11706132
On ComboBox Leave event, run a query in your database and see if the typed city exist. If it doesnt add it. You know how to add and run queries in the databse right?

-Nauman
0
 
LVL 37

Expert Comment

by:gregoryyoung
ID: 11706148
sure ... make it a combobox (which allows typing) then when they say ok check to see if the value they enterred is in the list, if not insert it ...
0
 

Author Comment

by:jvoros1
ID: 11706513
Is there a way to do it on the fly check as they type in each letter??
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LVL 37

Expert Comment

by:gregoryyoung
ID: 11706530
yeah there is ... you can trap the OnKeyPress event and check your list for matches on the string they have typed so far
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LVL 8

Accepted Solution

by:
rajaloysious earned 500 total points
ID: 11707966
           private void combobox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
            {
                  int nCmbIdx = 0;
                  int nlength = 0;
                  string sprevval = "";
                  ComboBox cmbBox = (ComboBox)sender;

                  if (cmbBox.DroppedDown == false)
                        cmbBox.DroppedDown = true;
                  
                  nlength = cmbBox.SelectionStart;
                  sprevval = cmbBox.Text.Substring(0,nlength);
                  nCmbIdx = cmbBox.FindString(sprevval + e.KeyChar.ToString());

                  //if the item exists
                  if (nCmbIdx >= 0)
                  {
                        e.Handled = true;
                        cmbBox.SelectedIndex = nCmbIdx;
                        cmbBox.SelectedItem = cmbBox.Items[nCmbIdx];
                        cmbBox.SelectionStart = nlength + 1;
                        cmbBox.SelectionLength = cmbBox.Text.Length - sprevval.Length;
                  }
                  else
                  {
                        //item is new one
                        //Have a track and add it on combobox1_Leave
                        Set a flag = true and a varaible to remember the new item
                        bNewItem = true;
                        sNewItem = sprevval + e.KeyChar.ToString()
                  }

            private void combobox1_Leave(object sender, System.EventArgs e)
            {
                  combobox1.Items.Add sNewItem
                  nCmbIdx = cmbBox.FindString(sNewItem);
                  cmbBox.SelectedIndex = nCmbIdx;
            }

Cheers...
0
 

Author Comment

by:jvoros1
ID: 11709278
Thanks I tried on keypress
 cmbCity.SelectedIndex = cmbCity.FindString(e.KeyChar.ToString());
but this only gets first letter is there a way to get them to narrow down so they can type Toro and as they type it narrows it down.
0
 
LVL 37

Expert Comment

by:gregoryyoung
ID: 11709297
why not use the .Text property to access the text they have typed in so far ? or you could just maintain a string of the data they have enterred so far.
0
 

Author Comment

by:jvoros1
ID: 11709397
Thanks rajaloysious  I got it working that was great help
0

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