c# - 用于实现 "Search as you type"Combobox 的 BackgroundWorker

Question

我为我的组合框创建了一个代码，它可以在存储过程的帮助下在 Sql Server 上的一个非常大的表中搜索地址(我正在使用 Entity Framework )。我的存储过程返回 10 次匹配，我的代码用搜索结果填充组合框。为此，我使用了 BackgroundWorker。

但是我现在遇到了大问题:- 虽然组合框充满了我的搜索结果，但它总是选择第一项。即使我只输入一个字母，整个文本也会被选中；

• 此后搜索地址不再有效。它只在这 10 个结果中搜索，我不知道如何解决这个问题。这是我的全部代码，它给我带来了问题:

  public String searchedItem = "";    
  public delegate void DelegateUpdateComboboxSelection(ComboBox myCombo,string value,int count);
  
  BackgroundWorker m_bgworker = new BackgroundWorker();        
  static AutoResetEvent resetWorker = new AutoResetEvent(false);
  
  m_bgworker.WorkerSupportsCancellation = true;
  m_bgworker.DoWork += new DoWorkEventHandler(FillComboboxBindingList);
  m_bgworker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(m_bgworker_RunWorkerCompleted);
  
  BindingList<spIskalnikNaslovi_Result1> m_addresses = new BindingList<SP_Result1>(); 
  
  
  void m_bgworker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
  {
      int count = (int)((object[])e.Result)[0];
      string value = (string)((object[])e.Result)[1];
      ComboBox myCombo = (ComboBox)((object[])e.Result)[2];
      DelegateUpdateComboboxSelection ndelegate = new DelegateUpdateComboboxSelection(UpdateComboSelection);
      if (this.InvokeRequired)
      {
          Invoke(ndelegate, new object[] {myCombo, value, count});
          return; 
      }
      else
      {
          UpdateComboSelection(myCombo, value, count);
          return; 
      }               
  }
  
  private void UpdateComboSelection(ComboBox myCombo, String value, int count)
  {
      myCombo = comboBox9;
      myCombo.DataSource = m_addresses;
      searchedItem = myCombo.Text;  
      if (count > 0)
      {
          myCombo.SelectionStart = value.Length;
          myCombo.SelectionLength = searchedItem.Length - value.Length;
          myCombo.DroppedDown = true;
      }
      else
      {
          myCombo.DroppedDown = false;
          myCombo.SelectionStart = value.Length;
      }
  } 
  
  public void FillComboboxBindingList(object sender, DoWorkEventArgs e)
  {
      if (m_bgworker.CancellationPending)
      {
          resetWorker.Set();
          e.Cancel = true;
          return;
      }
      else
      {
          string value = (String)((Object[])e.Argument)[0];
          List<SP_Result1> result;
          result = _vsebina.SP_searcher(value).ToList<SP_Result1>();
          m_addresses = new BindingList<SP_Result1>();
  
          foreach (SP_Result1 rez in result)
          {
              if (m_addresses.Contains(rez))
              {
                  continue;
              }
              else
              {
                  m_addresses.Add(rez);
              }
          }
          foreach (SP_Result1 r in m_addresses.ToArray())
          {
              if (!result.Contains(r))
              {
                  m_addresses.Remove(r);
              }
          }
          e.Result = new object[] { rezultat.Count, vrednost, null };
          return;
      }
  }
  
  private void comboBox9_KeyUp(object sender, KeyEventArgs e)
  {
      if (e.KeyCode == Keys.Back)
      {
          int searchStart = comboBox9.SelectionStart;
          if (searchStart > 0)
          {
              searchStart--;
              if (searchStart == 0)
              {
                  comboBox9.Text = "";
              }
              else
              {
                  comboBox9.Text = comboBox9.Text.Substring(0, searchStart + 1);
              }
          }
          else 
          {
              searchStart = 0;
          }
          e.Handled = true;
      }
  }
  
  private void comboBox9_Enter(object sender, EventArgs e)
  {
      comboBox9.SelectionStart = 0;
      comboBox9.SelectionLength = 0;
  }
  
  private void comboBox9_Click(object sender, EventArgs e)
  {
      comboBox9.Text = "";
  }
  
  private void comboBox9_KeyPress(object sender, KeyPressEventArgs e)
  {
      Search();
  }
  
  public void Search()
  {
      if (comboBox9.Text.Length < 4)
      {
          return;
      }
      else
      {
          if (m_bgworker.IsBusy)
          {
             m_bgworker.CancelAsync();
  
             m_bgworker = new BackgroundWorker();
             m_bgworker.WorkerSupportsCancellation = true;
             m_bgworker.DoWork += new DoWorkEventHandler(FillComboboxBindingList);
             m_bgworker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(m_bgworker_RunWorkerCompleted);
          }
          m_bgworker.RunWorkerAsync(new object[] { comboBox9.Text, comboBox9 });
      }  
  }
  

也许有人可以启发我，我做错了什么。这是我第一次使用 BackgroundWorker。我不知道，怎么办以任何其他方式使用组合框实现“键入时搜索”，因为我的地址数据表非常大(百万条记录)。

提前感谢您提供任何类型的帮助或代码示例。

弗拉基米尔

编辑 1:好的，这是我的代码，在我使用 BackGroundWorker 之前。它有效，但搜索速度非常非常慢(最多可能需要 10 秒):

    private void comboBox9_TextChanged(object sender, EventArgs e)
    {
        if (comboBox9.Text.Length < 4)
        {
            return;
        }
        else
        {
            FillCombobox(comboBox9.Text, comboBox9);
        }

    }

    public void FillCombobox(string value, ComboBox myCombo)
    {
        List<spIskalnikNaslovi_Result1> result;
        result = _vsebina.spIskalnikNaslovi1(value).ToList(); 
        if (result.Count() > 0)
        {
            myCombo.DataSource = result;
            myCombo.ValueMember = "HS_MID";
            myCombo.DisplayMember = "NASLOV1";
            var searchedItem = myCombo.Items[0].ToString();
            myCombo.SelectionStart = value.Length;
            myCombo.SelectionLength = searchedItem.Length - value.Length;
            myCombo.DroppedDown = true;
        }
        else
        {
            myCombo.DroppedDown = false;
            myCombo.SelectionStart = value.Length;
        }
        return;
    }

有没有办法在没有 backgroundworker 的情况下加快速度？

Answer 1

创建一个按钮，你将调用 searchbutton并在此按钮的 click_event 中调用运行 backgroundworker 的 search() 方法填充组合框清除组合框的 key_press 事件，它将起作用错误是你的 key_press 事件调用了你的搜索方法发生的每一次击键所以取回它