Question

我在Windows Forms应用程序中使用CheckBoxList，并尝试为其应用数据源。

拥有一个DataTable，'dt'，列id，name和ischecked，我使用了这样的代码：

((ListBox)MyCheckBoxList).DataSource = dt;
((ListBox)MyCheckBoxList).DisplayMember = "name";
((ListBox)MyCheckBoxList).ValueMember = "id";

如何为MyCheckBoxList中的所有项设置CheckState？

我将此值保留在我的数据表中，并希望将它们与MyCheckBoxList链接。

Answer 1

我分两步确定了我的问题。首先，我应用了数据源，然后在圆圈中设置每个项目的Checked属性，如下面的代码所示：

((ListBox)MyCheckBoxList).DataSource = dt;
((ListBox)MyCheckBoxList).DisplayMember = "name";
                    ...

for (int i = 0; i < folloving.Items.Count; i++ )
{
    DataRowView row = (DataRowView)MyCheckBoxList.Items[i];
    bool isChecked = Convert.ToBoolean(row["checked"]);
    MyCheckBoxList.SetItemChecked(i, isChecked);
}

Answer 2

作为另一种解决方法，我实现了CheckedListBox.Format事件，以自动使用数据更新显示的CheckedState;并实现CheckedListBox.ItemCheck事件以使用CheckedState自动更新数据。

private DataTable myDataTable = null;
private BindingSource myBindingSource = new BindingSource();

// Column Name Constants
private const string C_ITEM_INDEX = "Item_Index";      // CheckedListBox Item's Index
private const string C_ITEM_TEXT = "Item_Text";        // Item's Text
private const string C_ITEM_CHECKED = "Item_Checked";  // Item's Checked State
private const string C_DATA_KEY = "Data_Key";          // Arbitrary Key Value for Relating Item to Other Data

private void Startup()
{
  // Create DataTable 
  // This DataTable has 4 Columns described by the constants above
  myDataTable = new DataTable();
  myDataTable.Columns.Add(new DataColumn(C_ITEM_INDEX, typeof(Int32)));
  myDataTable.Columns[C_ITEM_INDEX].DefaultValue = 0;
  myDataTable.Columns.Add(new DataColumn(C_ITEM_TEXT, typeof(string)));
  myDataTable.Columns[C_ITEM_TEXT].DefaultValue = "";

  // I personally like Integer 1=true, 0=false values.  typeof(bool) will also work.
  myDataTable.Columns.Add(new DataColumn(C_ITEM_CHECKED, typeof(Int32)));
  myDataTable.Columns[C_ITEM_CHECKED].DefaultValue = 0;

  // Other columns can be included in the DataTable
  myDataTable.Columns.Add(new DataColumn(C_DATA_KEY, typeof(Int32)));
  myDataTable.Columns[C_DATA_KEY].DefaultValue = 0;     
  myDataTable.AcceptChanges();

  // Bind the DataTable's DefaultView to the CheckedListBox
  myBindingSource.DataSource = myDataTable.DefaultView;
  this.myCheckedListBox.DataSource = myBindingSource;

  // Set the DisplayMember to the DataColumn you want displayed as the CheckedListBox Items's Text
  this.myCheckedListBox.DisplayMember = C_ITEM_TEXT;

  // Set the ValueMember to the Data.  Note:  The ValueMember is not displayed and is Not the CheckBox value.
  this.myCheckedListBox.ValueMember = C_DATA_KEY;

  // Hookup Event Handler for the CheckedListBox.Format Event.  
  /// * The Format event enables us to just in time update the CheckBoxes with the values in the DataTable
  this.myCheckedListBox.Format += myCheckedListBox_Format;

  // Hookup Event Handler for the CheckedListBox.ItemCheck Event.
  /// * The ItemCheck event enables us to just in time update the DataTable with the values from the Item CheckBoxes
  this.myCheckedListBox.ItemCheck += myCheckedListBox_ItemCheck;
}


void myCheckedListBox_Format(object sender, ListControlConvertEventArgs e)
{
  /// * The Format event enables us to just in time update the CheckBoxes with the values in the DataTable
  // Retrieve the Index of the Item in the CheckedListBox by finding the DataRowView in the BindingSource
  //   Note:  Use a column with unique values for the BindingSource.Find() function
  int listindex = myBindingSource.Find(C_ITEM_INDEX, ((DataRowView)e.ListItem)[C_ITEM_INDEX]);

  // The argument, e.ListItem, is the current DataRowView in the DataTable's DefaultView
  // Check to see if the checkbox value is different from the data
  if (((CheckedListBox)sender).GetItemChecked(listindex) !=  Convert.ToBoolean(((DataRowView)e.ListItem)[C_ITEM_CHECKED]))
  {
    // Set the CheckList Item's CheckState to match the data
    ((CheckedListBox)sender).SetItemChecked(listindex, Convert.ToBoolean(((DataRowView)e.ListItem)[C_ITEM_CHECKED]));
  }
}


void myCheckedListBox_ItemCheck(object sender, ItemCheckEventArgs e)
{
  /// * The ItemCheck event enables us to just in time update the DataTable with the values from the Item CheckBoxes
  // Update the data with the new CheckState value.  
  if (e.NewValue == CheckState.Checked)
  {
    myDataTable.DefaultView[e.Index][C_ITEM_CHECKED] = 1;
  }
  else
  {
    myDataTable.DefaultView[e.Index][C_ITEM_CHECKED] = 0;
  }
  // Update other data values too if you need to.
}

Answer 3

我不确定是否有办法通过ValueMember属性设置检查。

你可以试一试：

foreach (DataRow item in dt.Rows)
{
     MyCheckedListBox.Items.Add(item["Name"].ToString(), Convert.ToBoolean(item["Checked"]));
}

在CheckBoxList中使用数据源

3 个答案: