Question

我有一个绑定到对象列表的下拉列表。该列表可以有超过20000个项目。我不想立即填充列表。但是，当用户键入列表的文本部分时，控件应该开始过滤列表并显示匹配项。

我正在尝试以下方法：

    private void cboName_TextChanged(object sender, EventArgs e)
    {
        var query1 = allNames.Where(x => x.firstname.Contains(cboName.Text) || x.lastname.Contains(cboName.Text)).ToList();

        cboName.DataSource = query1;
        cboName.ValueMember = "id";
        cboName.DisplayMember = "firstname";
    }

但它在性能方面不起作用。有没有办法实现这个目标？

Answer 1

根据您的要求，您可以试试这个

TextBox.AutoCompleteMode Property

示例：

private void Form1_Load(object sender, EventArgs e)
{
    // Create the list to use as the custom source.  
    var source = new AutoCompleteStringCollection();
    source.AddRange(new string[]
                    {
                        "January",
                        "February",
                        "March",
                        "April",
                        "May",
                        "June",
                        "July",
                        "August",
                        "September",
                        "October",
                        "November",
                        "December"
                    });

    // Create and initialize the text box. 
    var textBox = new TextBox
                  {
                      AutoCompleteCustomSource = source,
                      //Appends both Suggest and Append options.
                      AutoCompleteMode = 
                          AutoCompleteMode.SuggestAppend,
                      AutoCompleteSource =
                          AutoCompleteSource.CustomSource,
                      Location = new Point(20, 20),
                      Width = ClientRectangle.Width - 40,
                      Visible = true
                  };

    // Add the text box to the form.
    Controls.Add(textBox);
}

Answer 2

您可以坚持使用已有的代码。

private void cboName_TextChanged(object sender, EventArgs e)
    {
        var query1 = allNames.Where(x => x.firstname.Contains(cboName.Text) || x.lastname.Contains(cboName.Text)).ToList();

        cboName.DataSource = query1;
        cboName.ValueMember = "id";
        cboName.DisplayMember = "firstname";
    }

您可以在过滤前设置延迟，或者使用keydown并聆听enter密钥，然后过滤列表。

过滤下拉列表

2 个答案: