CODEWITHSUNDEEP
c#winformscombobox
ghd
ghd

Reputation: 545

Update a combo box automatically when first combo box gets some value

I have two combo boxes. I insert one value in first combo box and now i want that my second combo box updates its value according to first one. How should i do that?

Upvotes: 4

Views: 21098

Answers (4)

Murat Topcu
Murat Topcu

Reputation: 1

I want to select Ders this cmbDers and then cmbKonu update related SQL like that Country-City. But I get a datatype mismatch. What is problem?

Form Load OleDbDataAdapter adp = new OleDbDataAdapter("select * from Ders ", baglanti); DataTable dt = new DataTable(); baglanti.Open(); adp.Fill(dt); cmbDers.DataSource = dt; cmbDers.DisplayMember = "DersAd"; cmbDers.ValueMember = "DersID"; baglanti.Close();

private void cmbDers_SelectedIndexChanged(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    OleDbDataAdapter adp = new OleDbDataAdapter ("select * from Konu where DersID = '" +cmbDers.SelectedItem+"'",baglanti);   
    adp.Fill(dt);
    cmbKonu.DataSource = dt;
    cmbKonu.DisplayMember = "KonuAd";
    cmbKonu.ValueMem`enter code here`ber = "KonuID";
    baglanti.Close();`enter code here`

Upvotes: 0

Gary Kindel
Gary Kindel

Reputation: 17709

Code Example, Winform with two comboBoxes databound to two tables in a dataset. Table "lstCountries" list of current countries Table "lstState" list of all states/provinces for all countries.

Table lstCountries(Int32 CountryID,string CountryName) Table lstStates(Int32 StateID, Int32 CountryID, string StateName)

In this code, I populate cboState based in value selected cboCountry while both combodropdowns are bound to data tables fetched from a database.

//  Load data from database (not shown)
// _dataSet.Tables["lstCountries"] datasource for cboCountry
// _dataSet.Tables["lstStates"] datasource for cboState
//  
// cboCountry - comboDropDown - List on countries 
// cboState  = comboDropDown  - List of states

// Use boolean bloading to prevent setting datasource for cboState when cboCountry is intially loaded.

    void cboCountry_SelectedIndexChanged(object sender, EventArgs e)
    {
        ComboBox cbo = (sender as ComboBox);
        if (cbo.SelectedIndex > -1 && !bloading)
        {
            Int32 countryID = Convert.ToInt32(((System.Data.DataRowView)(cbo.SelectedItem)).Row.ItemArray[0].ToString());

            cboState.Text = "";
            DataView view = _dataSet.Tables["lstStates"].DefaultView;
            view.RowFilter = string.Format("CountryID={0}", countryID);
            DataTable table = view.ToTable();
            cboState.DataSource = table;
            cboState.SelectedIndex = -1;
    }

Upvotes: 0

abatishchev
abatishchev

Reputation: 100368

Subscribe to first combobox's value changed event and populate the second:

combobox1.SelectedIndexChanged+= new EventHandler(ListBox1_SelectedIndexChanged);

private combobox1_SelectedIndexChanged(object sender, EventArgs e)
{
    // do stuff with combobox2
}

or

combobox1.SelectedValueChanged += new EventHandler(ListBox1_SelectedValueChanged);

private combobox1_SelectedValueChanged(object sender, EventArgs e)
{
    // do stuff with combobox2
}

Population:

combobox2.Items.Add(new object());
combobox2.Items.Add(new ListItem("caption", "value"));
// etc

Find an existing item:

var index = combobox2.FindStringExact(combobox1.SelectedText);
if (index != -1)
    comobox2.SelectedItem = combobox2.Items[index];

Upvotes: 2

fletcher
fletcher

Reputation: 13790

Handle the SelectedIndexChanged event for the first ComboBox, then update the second combo box based on the SelectedItem value for the first ComboBox.

A quick example (sans error handling when retrieving the SelectedItem):

public partial class Form1 : Form
{
    private string[] comboBox1Range = new[] { "A", "B", "C", "D" };
    private string[] comboBox2RangeA = new[] { "A1", "A2", "A3", "A4" };
    private string[] comboBox2RangeB = new[] { "B1", "B2", "B3", "B4" };
    private string[] comboBox2RangeC = new[] { "C1", "C2", "C3", "C4" };
    private string[] comboBox2RangeD = new[] { "D1", "D2", "D3", "D4" };

    public Form1()
    {
        InitializeComponent();
        comboBox1.SelectedIndexChanged += comboBox1_SelectedIndexChanged;
        comboBox1.Items.AddRange(comboBox1Range);
    }

    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string selectedValue = comboBox1.SelectedItem as string;

        switch (selectedValue)
        {
            case "A":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeA);
                break;
            case "B":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeB);
                break;
            case "C":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeC);
                break;
            case "D":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeD);
                break;
        }
    }
}

Upvotes: 9

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