C# winforms 組合框動態自動完成

Question

我的問題與此類似： 如何動態更改 C# 組合框或文本框中的自動完成條目？ 但我仍然沒有找到解決方案。

問題簡述：

我有一個ComboBox和大量要在其中顯示的記錄。 當用戶開始輸入時，我想加載以輸入文本開頭的記錄並為用戶提供自動完成功能。 如上面的主題所述，我無法在сomboBox_TextChanged上加載它們，因為我總是覆蓋以前的結果並且從未看到它們。

我可以只使用ComboBox嗎？ （不是TextBox或ListBox ）

我使用這個設置：

сomboBox.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
сomboBox.AutoCompleteSource = AutoCompleteSource.CustomSource;

Answer 1

我最近也遇到了這些需求。 我在不編寫代碼的情況下設置了以下屬性並且它可以工作。 看看這是否對你有幫助。

Answer 2

這是我的最終解決方案。 它適用於大量數據。 我使用Timer來確保用戶想要找到當前值。 看起來很復雜，其實不然。 感謝Max Lambertini的想法。

        private bool _canUpdate = true; 

        private bool _needUpdate = false;       

        //If text has been changed then start timer
        //If the user doesn't change text while the timer runs then start search
        private void combobox1_TextChanged(object sender, EventArgs e)
        {
            if (_needUpdate)
            {
                if (_canUpdate)
                {
                    _canUpdate = false;
                    UpdateData();                   
                }
                else
                {
                    RestartTimer();
                }
            }
        }

        private void UpdateData()
        {
            if (combobox1.Text.Length > 1)
            {
                List<string> searchData = Search.GetData(combobox1.Text);
                HandleTextChanged(searchData);
            }
        }       

        //If an item was selected don't start new search
        private void combobox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            _needUpdate = false;
        }

        //Update data only when the user (not program) change something
        private void combobox1_TextUpdate(object sender, EventArgs e)
        {
            _needUpdate = true;
        }

        //While timer is running don't start search
        //timer1.Interval = 1500;
        private void RestartTimer()
        {
            timer1.Stop();
            _canUpdate = false;
            timer1.Start();
        }

        //Update data when timer stops
        private void timer1_Tick(object sender, EventArgs e)
        {
            _canUpdate = true;
            timer1.Stop();
            UpdateData();
        }

        //Update combobox with new data
        private void HandleTextChanged(List<string> dataSource)
        {
            var text = combobox1.Text;

            if (dataSource.Count() > 0)
            {
                combobox1.DataSource = dataSource;  

                var sText = combobox1.Items[0].ToString();
                combobox1.SelectionStart = text.Length;
                combobox1.SelectionLength = sText.Length - text.Length;
                combobox1.DroppedDown = true;


                return;
            }
            else
            {
                combobox1.DroppedDown = false;
                combobox1.SelectionStart = text.Length;
            }
        }

這個解決方案不是很酷。 因此，如果有人有其他解決方案，請與我分享。

Answer 3

是的，您當然可以……但需要一些工作才能使其無縫運行。 這是我想出的一些代碼。 請記住，它不使用組合框的自動完成功能，如果您使用它來篩選大量項目，它可能會很慢......

string[] data = new string[] {
    "Absecon","Abstracta","Abundantia","Academia","Acadiau","Acamas",
    "Ackerman","Ackley","Ackworth","Acomita","Aconcagua","Acton","Acushnet",
    "Acworth","Ada","Ada","Adair","Adairs","Adair","Adak","Adalberta","Adamkrafft",
    "Adams"

};
public Form1()
{
    InitializeComponent();
}

private void comboBox1_TextChanged(object sender, EventArgs e)
{
    HandleTextChanged();
}

private void HandleTextChanged()
{
    var txt = comboBox1.Text;
    var list = from d in data
               where d.ToUpper().StartsWith(comboBox1.Text.ToUpper())
               select d;
    if (list.Count() > 0)
    {
        comboBox1.DataSource = list.ToList();
        //comboBox1.SelectedIndex = 0;
        var sText = comboBox1.Items[0].ToString();
        comboBox1.SelectionStart = txt.Length;
        comboBox1.SelectionLength = sText.Length - txt.Length;
        comboBox1.DroppedDown = true;
        return;
    }
    else
    {
        comboBox1.DroppedDown = false;
        comboBox1.SelectionStart = txt.Length;
    }
}

private void comboBox1_KeyUp(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Back)
    {
        int sStart = comboBox1.SelectionStart;
        if (sStart > 0)
        {
            sStart--;
            if (sStart == 0)
            {
                comboBox1.Text = "";
            }
            else
            {
                comboBox1.Text = comboBox1.Text.Substring(0, sStart);
            }
        }
        e.Handled = true;
    }
}

Answer 4

我寫了這樣的東西......

private void frmMain_Load(object sender, EventArgs e)
{
    cboFromCurrency.Items.Clear();
    cboComboBox1.AutoCompleteMode = AutoCompleteMode.Suggest;
    cboComboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;
    // Load data in comboBox => cboComboBox1.DataSource = .....
    // Other things
}

private void cboComboBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    cboComboBox1.DroppedDown = false;
}

僅此而已 (Y)

Answer 5

我發現 Max Lambertini 的回答非常有幫助，但已經修改了他的 HandleTextChanged 方法：

    //I like min length set to 3, to not give too many options 
    //after the first character or two the user types
    public Int32 AutoCompleteMinLength {get; set;}

    private void HandleTextChanged() {
        var txt = comboBox.Text;
        if (txt.Length < AutoCompleteMinLength)
            return;

        //The GetMatches method can be whatever you need to filter 
        //table rows or some other data source based on the typed text.
        var matches = GetMatches(comboBox.Text.ToUpper());

        if (matches.Count() > 0) {
            //The inside of this if block has been changed to allow
            //users to continue typing after the auto-complete results
            //are found.
            comboBox.Items.Clear();
            comboBox.Items.AddRange(matches);
            comboBox.DroppedDown = true;
            Cursor.Current = Cursors.Default;
            comboBox.Select(txt.Length, 0);
            return;
        }
        else {
            comboBox.DroppedDown = false;
            comboBox.SelectionStart = txt.Length;
        }
    }

Answer 6

此代碼寫在您的表單加載上。 當用戶在組合框中輸入字母時，它會顯示數據庫中的所有 Tour。 此代碼會根據用戶的需要自動建議並附加正確的選擇。

            con.Open();
            cmd = new SqlCommand("SELECT DISTINCT Tour FROM DetailsTB", con);
            SqlDataReader sdr = cmd.ExecuteReader();
            DataTable dt = new DataTable();
            dt.Load(sdr);
            combo_search2.DisplayMember = "Tour";
            combo_search2.DroppedDown = true;

            List<string> list = new List<string>();
            foreach (DataRow row in dt.Rows)
            {
                list.Add(row.Field<string>("Tour"));
            }
            this.combo_search2.Items.AddRange(list.ToArray<string>());
            combo_search2.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
            combo_search2.AutoCompleteSource = AutoCompleteSource.ListItems;
            con.Close();

Answer 7

之前的回復都是缺點。 提供自己的版本，並在下拉列表中選擇所需的項目：

    private ConnectSqlForm()
    {
        InitializeComponent();
        cmbDatabases.TextChanged += UpdateAutoCompleteComboBox;
        cmbDatabases.KeyDown += AutoCompleteComboBoxKeyPress;
    }

    private void UpdateAutoCompleteComboBox(object sender, EventArgs e)
    {
        var comboBox = sender as ComboBox;
        if(comboBox == null)
        return;
        string txt = comboBox.Text;
        string foundItem = String.Empty;
        foreach(string item in comboBox.Items)
            if (!String.IsNullOrEmpty(txt) && item.ToLower().StartsWith(txt.ToLower()))
            {
                foundItem = item;
                break;
            }

        if (!String.IsNullOrEmpty(foundItem))
        {
            if (String.IsNullOrEmpty(txt) || !txt.Equals(foundItem))
            {
                comboBox.TextChanged -= UpdateAutoCompleteComboBox;
                comboBox.Text = foundItem;
                comboBox.DroppedDown = true;
                Cursor.Current = Cursors.Default;
                comboBox.TextChanged += UpdateAutoCompleteComboBox;
            }

            comboBox.SelectionStart = txt.Length;
            comboBox.SelectionLength = foundItem.Length - txt.Length;
        }
        else
            comboBox.DroppedDown = false;
    }

    private void AutoCompleteComboBoxKeyPress(object sender, KeyEventArgs e)
    {
        var comboBox = sender as ComboBox;
        if (comboBox != null && comboBox.DroppedDown)
        {
            switch (e.KeyCode)
            {
                case Keys.Back:
                    int sStart = comboBox.SelectionStart;
                    if (sStart > 0)
                    {
                        sStart--;
                        comboBox.Text = sStart == 0 ? "" : comboBox.Text.Substring(0, sStart);
                    }
                    e.SuppressKeyPress = true;
                    break;
            }

        }
    }

Answer 8

 using (var client = new UserServicesClient())
 {
     var list = new AutoCompleteStringCollection();
     list.AddRange(client.ListNames(query).ToArray());
     comboBoxName.AutoCompleteCustomSource = list;
 }

Answer 9

這是開始工作的主要痛苦。 我遇到了一堆死胡同，但最終結果相當直接。 希望它可以對某人有益。 它可能需要一點點吐痰和潤色，僅此而已。

注意：_addressFinder.CompleteAsync 返回一個 KeyValuePairs 列表。

public partial class MyForm : Form
{
    private readonly AddressFinder _addressFinder;
    private readonly AddressSuggestionsUpdatedEventHandler _addressSuggestionsUpdated;

    private delegate void AddressSuggestionsUpdatedEventHandler(object sender, AddressSuggestionsUpdatedEventArgs e);

    public MyForm()
    {
        InitializeComponent();

        _addressFinder = new AddressFinder(new AddressFinderConfigurationProvider());

        _addressSuggestionsUpdated += AddressSuggestions_Updated;

        MyComboBox.DropDownStyle = ComboBoxStyle.DropDown;
        MyComboBox.DisplayMember = "Value";
        MyComboBox.ValueMember = "Key";
    }

    private void MyComboBox_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (char.IsControl(e.KeyChar))
        {
            return;
        }

        var searchString = ThreadingHelpers.GetText(MyComboBox);

        if (searchString.Length > 1)
        {
            Task.Run(() => GetAddressSuggestions(searchString));
        }
    }

    private async Task GetAddressSuggestions(string searchString)
    {
        var addressSuggestions = await _addressFinder.CompleteAsync(searchString).ConfigureAwait(false);

        if (_addressSuggestionsUpdated.IsNotNull())
        {
            _addressSuggestionsUpdated.Invoke(this, new AddressSuggestionsUpdatedEventArgs(addressSuggestions));
        }
    }

    private void AddressSuggestions_Updated(object sender, AddressSuggestionsUpdatedEventArgs eventArgs)
    {
        try
        {
            ThreadingHelpers.BeginUpdate(MyComboBox);

            var text = ThreadingHelpers.GetText(MyComboBox);

            ThreadingHelpers.ClearItems(MyComboBox);

            foreach (var addressSuggestions in eventArgs.AddressSuggestions)
            {
                ThreadingHelpers.AddItem(MyComboBox, addressSuggestions);
            }

            ThreadingHelpers.SetDroppedDown(MyComboBox, true);

            ThreadingHelpers.ClearSelection(MyComboBox);
            ThreadingHelpers.SetText(MyComboBox, text);
            ThreadingHelpers.SetSelectionStart(MyComboBox, text.Length);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex);
        }
        finally
        {
            ThreadingHelpers.EndUpdate(MyComboBox);
        }
    }

    private class AddressSuggestionsUpdatedEventArgs : EventArgs
    {
        public IList<KeyValuePair<string, string>> AddressSuggestions { get; private set; }

        public AddressSuggestionsUpdatedEventArgs(IList<KeyValuePair<string, string>> addressSuggestions)
        {
            AddressSuggestions = addressSuggestions;
        }
    }
}

ThreadingHelpers 只是以下形式的一組靜態方法：

    public static string GetText(ComboBox comboBox)
    {
        if (comboBox.InvokeRequired)
        {
            return (string)comboBox.Invoke(new Func<string>(() => GetText(comboBox)));
        }

        lock (comboBox)
        {
            return comboBox.Text;
        }
    }

    public static void SetText(ComboBox comboBox, string text)
    {
        if (comboBox.InvokeRequired)
        {
            comboBox.Invoke(new Action(() => SetText(comboBox, text)));
            return;
        }

        lock (comboBox)
        {
            comboBox.Text = text;
        }
    }

Answer 10

采取 2. 我下面的回答並沒有讓我一直達到預期的結果，但它可能對某些人仍然有用。 ComboBox 的自動選擇功能讓我很痛苦。 這個使用位於 ComboBox 頂部的 TextBox，允許我忽略 ComboBox 本身中出現的任何內容，只響應選擇更改事件。

1. 創建表格
2. 添加組合框
   • 設置所需的大小和位置
   • 將 DropDownStyle 設置為DropDown
   • 將 TabStop 設置為false
   • 將 DisplayMember 設置為Value （我使用的是 KeyValuePairs 列表）
   • 將 ValueMember 設置為Key
3. 添加面板
   • 設置為與 ComboBox 相同的大小
   • 用面板覆蓋 ComboBox（這說明標准 ComboBox 比標准 TextBox 高）
4. 添加文本框
   • 將 TextBox 放在面板的頂部
   • 將 TextBox 的底部與 Panel/ComboBox 的底部對齊

背后的代碼

public partial class TestForm : Form
{
    // Custom class for managing calls to an external address finder service
    private readonly AddressFinder _addressFinder;

    // Events for handling async calls to address finder service
    private readonly AddressSuggestionsUpdatedEventHandler _addressSuggestionsUpdated;
    private delegate void AddressSuggestionsUpdatedEventHandler(object sender, AddressSuggestionsUpdatedEventArgs e);

    public TestForm()
    {
        InitializeComponent();

        _addressFinder = new AddressFinder(new AddressFinderConfigurationProvider());
        _addressSuggestionsUpdated += AddressSuggestions_Updated;
    }

    private void textBox1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
    {
        if (e.KeyCode == Keys.Tab)
        {
            comboBox1_SelectionChangeCommitted(sender, e);
            comboBox1.DroppedDown = false;
        }
    }

    private void textBox1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Up)
        {
            if (comboBox1.Items.Count > 0)
            {
                if (comboBox1.SelectedIndex > 0)
                {
                    comboBox1.SelectedIndex--;
                }
            }

            e.Handled = true;
        }
        else if (e.KeyCode == Keys.Down)
        {
            if (comboBox1.Items.Count > 0)
            {
                if (comboBox1.SelectedIndex < comboBox1.Items.Count - 1)
                {
                    comboBox1.SelectedIndex++;
                }
            }

            e.Handled = true;
        }
        else if (e.KeyCode == Keys.Enter)
        {
            comboBox1_SelectionChangeCommitted(sender, e);
            comboBox1.DroppedDown = false;

            textBox1.SelectionStart = textBox1.TextLength;

            e.Handled = true;
        }
    }

    private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (e.KeyChar == '\r')  // Enter key
        {
            e.Handled = true;
            return;
        }

        if (char.IsControl(e.KeyChar) && e.KeyChar != '\b') // Backspace key
        {
            return;
        }

        if (textBox1.Text.Length > 1)
        {
            Task.Run(() => GetAddressSuggestions(textBox1.Text));
        }
    }

    private void comboBox1_SelectionChangeCommitted(object sender, EventArgs e)
    {
        if (comboBox1.Items.Count > 0 &&
            comboBox1.SelectedItem.IsNotNull() &&
            comboBox1.SelectedItem is KeyValuePair<string, string>)
        {
            var selectedItem = (KeyValuePair<string, string>)comboBox1.SelectedItem;

            textBox1.Text = selectedItem.Value;

            // Do Work with selectedItem
        }
    }

    private async Task GetAddressSuggestions(string searchString)
    {
        var addressSuggestions = await _addressFinder.CompleteAsync(searchString).ConfigureAwait(false);

        if (_addressSuggestionsUpdated.IsNotNull())
        {
            _addressSuggestionsUpdated.Invoke(this, new AddressSuggestionsUpdatedEventArgs(addressSuggestions));
        }
    }

    private void AddressSuggestions_Updated(object sender, AddressSuggestionsUpdatedEventArgs eventArgs)
    {
        try
        {
            ThreadingHelper.BeginUpdate(comboBox1);

            ThreadingHelper.ClearItems(comboBox1);

            if (eventArgs.AddressSuggestions.Count > 0)
            {
                foreach (var addressSuggestion in eventArgs.AddressSuggestions)
                {
                    var item = new KeyValuePair<string, string>(addressSuggestion.Key, addressSuggestion.Value.ToUpper());
                    ThreadingHelper.AddItem(comboBox1, item);
                }

                ThreadingHelper.SetDroppedDown(comboBox1, true);
                ThreadingHelper.SetVisible(comboBox1, true);
            }
            else
            {
                ThreadingHelper.SetDroppedDown(comboBox1, false);
            }
        }
        finally
        {
            ThreadingHelper.EndUpdate(comboBox1);
        }
    }

    private class AddressSuggestionsUpdatedEventArgs : EventArgs
    {
        public IList<KeyValuePair<string, string>> AddressSuggestions { get; }

        public AddressSuggestionsUpdatedEventArgs(IList<KeyValuePair<string, string>> addressSuggestions)
        {
            AddressSuggestions = addressSuggestions;
        }
    }
}

您在設置 ComboBox 的 DroppedDown 屬性時可能有也可能沒有問題。 我最終只是將它包裹在一個帶有空 catch 塊的 try 塊中。 不是一個很好的解決方案，但它有效。

有關 ThreadingHelpers 的信息，請參閱下面我的其他答案。

享受。