ComboBox.ValueMember 和 DisplayMember

Question

如何设置这个值？我有一个数据表，其中包含我想要在组合框中设置的所有数据，但我找不到如何设置它。

我试过了

ComboBox1.DataSource = dataTable;
ComboBox1.ValueMember = "id"; // --> once hes here, he just jumps out the method
ComboBox1.DisplayMember = "name";

没有编译错误，警告，什么都没有..只是跳出来！

这是填充数据表的查询

"Select * from \"Table\""

我用调试器检查，数据表已填满。列名称是“id”和“name”。组合框为空。我是第一次填写！

Answer 1

您不应该按此顺序设置列表框和/或组合框的

datasource

ComboBox1.DataSource = dataTable;

ComboBox1.ValueMember = "id"; 

ComboBox1.DisplayMember = "name";

相反，这是正确的顺序：

ComboBox1.ValueMember = "id"; 

ComboBox1.DisplayMember = "name";

ComboBox1.DataSource = dataTable;

注意：设置

datasource

应该是最后一行。

如果您先设置

datasource

，

SelectedIndexChanged

事件将触发，您可能会收到转换错误或其他异常。

Answer 2

使用键值对填充组合框

填充组合框的一个巧妙方法是将数据源设置为键值对列表。它还可能会激发使用存储在某种列表中的数据：

//Some values to show in combobox
string[] ports= new string[3] {"COM1", "COM2", "COM3"};

//Set datasource to string array converted to list of keyvaluepairs
combobox.Datasource = ports.Select(p => new KeyValuePair<string, string>(p, p)).ToList();

//Configure the combo control
combobox.DisplayMember = "Key";
combobox.ValueMember = "Value";
combobox.SelectedValue = ports[0];

也可以使用以下语法填充数据源：

ports.Select(p => new { Key = p, Value = p }).ToList();

该技术可以通过多列列表的更多属性名称进行扩展。

字典项等已经是键值对的对象可以直接使用

combobox.DataSource = new Dictionary<int, string>()
{
    {0, "COM1"},
    {1, "COM2"},
    {2, "COM3"},
}.ToList();
combobox.ValueMember = "Key";
combobox.DisplayMember = "Value";

元组可以这样初始化和使用

var ports= new List<Tuple<int, string>>()
{
    Tuple.Create(0, "COM1"),
    Tuple.Create(1, "COM2"),
    Tuple.Create(2, "COM3")
};

combobox.DataSource = ports;
combobox.ValueMember = "Item1";
combobox.DisplayMember = "Item2";

Answer 3

  ComboBox1.DataSource= dt; //the data table which contains data
  ComboBox1.ValueMember = "id";   // column name which you want in SelectedValue
  ComboBox1.DisplayMember = "name"; // column name that you need to display as text

Answer 4

他们拿着绳子...

ComboBox1.ValueMember = "id"; 
ComboBox1.DisplayMember = "name";

Answer 5

我也有同样的烦恼。在我的例子中，SelectedIndexChanged 事件触发并且只是跳出该方法。尝试不要使用 SelectedIndexChanged 事件。或者类似这样的东西：

ComboBox1.SelectedIndexChanged -= new System.EventHandler(ComboBox1_SelectedIndexChanged); 
ComboBox1.DataSource = dataTable; 
ComboBox1.ValueMember = "id";  
ComboBox1.DisplayMember = "name";
ComboBox1.SelectedIndexChanged += new System.EventHandler(ComboBox1_SelectedIndexChanged);

这对我有用。 =)

Answer 6

ComboBox1.ValueMember = dataTable.Columns["id"].ColumnsName;   // column name which the values are not visible 
ComboBox1.DisplayMember = dataTable.Columns ["name"].ColumnsName;
 /* 
       column name that you need to select item by proprity : 
ComboBox1.SelectedItem; 
Or   you can use easly this : 
ComboBox1.Text; 
*/

ComboBox1.DataSource= dataTable; //the data table which contains data 
// and this should be last :)

Answer 7

public class ComboDeger {
    private string yazi;
    private int deger;
    public ComboDeger(string stryazi, int strdeger) {
        this.yazi = stryazi;
        this.deger = strdeger;
    }
    public string yazisi {
        get {
            return yazi;
        }
    }
    public int degeri {
        get {
            return deger;
        }
    }
}
private void combobox_doldur() {
    ArrayList ComboDegerleri = new ArrayList();
    ComboDegerleri.Add(new ComboDeger("9 : NORMAL", 9));
    ComboDegerleri.Add(new ComboDeger("10 : ENGELLİ", 10));
    comboBox1.DataSource = ComboDegerleri;
    comboBox1.DisplayMember = "yazisi";
    comboBox1.ValueMember = "degeri";
}
private void Form3_Load(object sender, EventArgs e) {
    con.Open();
    combobox_doldur();

    // Populate the COMBOBOX using an array as DataSource.
}

Answer 8

你可以这样指定

  ComboBox1.ValueMember = "id";  
  ComboBox1.DisplayMember = "name"; 

Answer 9

也许不完全是所描述的问题，但在我的例子中，类型名称显示在 ComboBox 中，而不是 DisplayValue 中，尽管一切似乎都已正确连接。结果发现，类型的公共属性被定义为没有getter和setter！ :)

Answer 10

通过组合给定的示例并添加组合框中的选择：

private void Combobox_SelectedIndexChanged(object? sender, EventArgs e)
{
    string colorIdx = ((ComboBox)sender).SelectedValue.ToString();
    string colorName = ((System.Tuple<int, string>)((ComboBox)sender).SelectedItem).Item2;
}

private void AddItemsToComboBox()
{
    var myItems = new List<Tuple<int, string>>()
        {
            Tuple.Create(0, "Black"),
            Tuple.Create(1, "White"),
            Tuple.Create(2, "Red")
        };
    combobox.DataSource = myItems;
    combobox.ValueMember = "Item1";
    combobox.DisplayMember = "Item2";
}