在一个项目中,我遇到这样一个问题: 数据库字段只存储了一个字典ID1,在DataGrid中显示时,需要用相应的字典Value1来代替字典ID1显示.解决这个问题一般有两个方法:
方法1: 数据库查询Sql脚本直接把相应的字典Value1值查询出来.
方法2: 在显示DataGrid时,把相应的字典ID1转换成字典Value1显示.
关于方法1, 实现相对简单但是不灵活,并且我们采用的是强类型的DataSet,不想经常修改强类型Dataset的定义
关于方法2, 实现上相对复杂一些但是比较灵活,也不用破坏已定义的强类型DataSet.
于是我就决定采用方法二,上网也找了不少资料,终于在codeproejct找到一篇比较符合我需求的文章,我的实现逻辑如下:在创建Datagrid的column时,对于需要替换的column:Dict1用自定义的LookUpColumn来代替, 设置LookupColumn的Datasource DispalyMember及ValueMember,当Dataset中相应字段的值与LookupColumn的Datasource的ValueMember值相匹配时,显示相应的DispalyMember值.具体代码如下:
DataGridLookupColumn lcolumnex = new DataGridLookupColumn();
lcolumnex.MappingName = "Dict1";
lcolumnex.HeaderText = lcolumnex.MappingName;
lcolumnex.comboBox.ValueMember = "DictID";
lcolumnex.comboBox.DisplayMember = "DictValue";
lcolumnex.Width = 80;
lcolumnex.comboBox.DataSource = CommonValue.GetDictList();//返回Dict结构(有DictID,DictValue属性)组成的一个ArrayList
lTableStyle.GridColumnStyles.Add(lcolumnex);具体的DataGridLookupColumn类实现代码如下:
/**//*本代码原稿由http://www.codeproject.com/cs/miscctrl/RenDataGridComboBoxColumn.asp获取,并做了相应的改动 by Zendyhu
*/
DataGridLookupColumn#region DataGridLookupColumn
//**********************************************************************************************
// DataGridLookupColumn
//**********************************************************************************************
public class DataGridLookupColumn : DataGridColumnStyle
{ //DataGridLookupColumn {
private DataGridComboBox combobox;
private bool edit;
//-------------------------------------------------------------------------------------------
// Constructors and destructors
//-------------------------------------------------------------------------------------------
public DataGridLookupColumn()
{
combobox = new DataGridComboBox();
combobox.Visible = false;
combobox.DropDownStyle = ComboBoxStyle.DropDownList;
combobox.Leave += new EventHandler(ComboHide);
combobox.SelectionChangeCommitted += new EventHandler(ComboStartEditing);
edit = false;
} // DataGridLookupColumn
//-------------------------------------------------------------------------------------------
// Properties
//-------------------------------------------------------------------------------------------
public ComboBox comboBox
{
get
{
return combobox;
}
} // comboBox
//-------------------------------------------------------------------------------------------
// ComboBox event handlers
//-------------------------------------------------------------------------------------------
private void ComboHide(object sender, EventArgs e)
{
// When the ComboBox looses focus, then simply hide it.
combobox.Hide();
} // ComboHide
private void ComboStartEditing(object sender, EventArgs e)
{
// Enter edit mode.
edit = true;
base.ColumnStartedEditing((Control)sender);
} // ComboStartEditing
//-------------------------------------------------------------------------------------------
// Override DataGridColumnStyle
//-------------------------------------------------------------------------------------------
protected override void SetDataGridInColumn(DataGrid value)
{
// Add the ComboBox to the DataGrids controls collection.
// This ensures correct DataGrid scrolling.
value.Controls.Add(combobox);
base.SetDataGridInColumn(value);
} // SetDataGridInColumn
protected override void Abort(int rowNum)
{
// Abort edit mode, discard changes and hide the ComboBox.
edit = false;
Invalidate();
combobox.Hide();
} // Abort
protected override void Edit(System.Windows.Forms.CurrencyManager source, int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string instantText, bool cellIsVisible)
{
// Setup the ComboBox for action.
// This includes positioning the ComboBox and showing it.
// Also select the correct item in the ComboBox before it is shown.
combobox.Parent = this.DataGridTableStyle.DataGrid;
combobox.Bounds = bounds;
combobox.Size = new Size(this.Width, this.comboBox.Height);
comboBox.SelectedValue = base.GetColumnValueAtRow(source, rowNum).ToString();
combobox.Visible = (cellIsVisible == true) && (readOnly == false);
combobox.BringToFront();
combobox.Focus();
} // Edit
protected override bool Commit(System.Windows.Forms.CurrencyManager source, int rowNum)
{
// Commit the selected value from the ComboBox to the DataGrid.
if (edit == true)
{
edit = false;
this.SetColumnValueAtRow(source, rowNum, combobox.SelectedValue);
}
return true;
} // Commit
protected override object GetColumnValueAtRow(System.Windows.Forms.CurrencyManager source, int rowNum)
{
// Return the display text associated with the data, insted of the
// data from the DataGrid datasource.
return combobox.GetDisplayText(base.GetColumnValueAtRow(source, rowNum));
} // GetColumnValueAtRow
protected override void SetColumnValueAtRow(CurrencyManager source, int rowNum, object value)
{
// Save the data (value) to the DataGrid datasource.
// I try a few different types, because I often uses GUIDs as keys in my
// data.
// String.
try
{
base.SetColumnValueAtRow(source, rowNum, value.ToString());
return;
}
catch {}
// Guid.
try
{
base.SetColumnValueAtRow(source, rowNum, new Guid(value.ToString()));
return;
}
catch {}
// Object (default).
base.SetColumnValueAtRow(source, rowNum, value);
} // SetColumnValueAtRow
protected override int GetMinimumHeight()
{
// Return the ComboBox preferred height, plus a few pixels.
return combobox.PreferredHeight;
} // GetMinimumHeight
protected override int GetPreferredHeight(Graphics g, object val)
{
// Return the font height, plus a few pixels.
return FontHeight + 2;
} // GetPreferredHeight
protected override Size GetPreferredSize(Graphics g, object val)
{
// Return the preferred width.
// Iterate through all display texts in the dropdown, and measure each
// text width.
int widest = 0;
SizeF stringSize = new SizeF(0, 0);
foreach (string text in combobox.GetDisplayText())
{
stringSize = g.MeasureString(text, base.DataGridTableStyle.DataGrid.Font);
if (stringSize.Width > widest)
{
widest = (int)Math.Ceiling(stringSize.Width);
}
}
return new Size(widest + 25, combobox.PreferredHeight + 2);
} // GetPreferredSize
protected override void Paint(Graphics g, Rectangle bounds, CurrencyManager source, int rowNum)
{
Paint(g, bounds, source, rowNum, false);
} // Paint
protected override void Paint(Graphics g, Rectangle bounds, CurrencyManager source, int rowNum, bool alignToRight)
{
string text = GetColumnValueAtRow(source, rowNum).ToString();
Brush backBrush = new SolidBrush(base.DataGridTableStyle.BackColor);
Brush foreBrush = new SolidBrush(base.DataGridTableStyle.ForeColor);
Rectangle rect = bounds;
StringFormat format = new StringFormat();
// Handle that the row can be selected.
if (base.DataGridTableStyle.DataGrid.IsSelected(rowNum) == true)
{
backBrush = new SolidBrush(base.DataGridTableStyle.SelectionBackColor);
foreBrush = new SolidBrush(base.DataGridTableStyle.SelectionForeColor);
}
// Handle align to right.
if (alignToRight == true)
{
format.FormatFlags = StringFormatFlags.DirectionRightToLeft;
}
// Handle alignment.
switch (this.Alignment)
{
case HorizontalAlignment.Left:
format.Alignment = StringAlignment.Near;
break;
case HorizontalAlignment.Right:
format.Alignment = StringAlignment.Far;
break;
case HorizontalAlignment.Center:
format.Alignment = StringAlignment.Center;
break;
}
// Paint.
format.FormatFlags = StringFormatFlags.NoWrap;
g.FillRectangle(backBrush, rect);
rect.Offset(0, 2);
rect.Height -= 2;
g.DrawString(text, this.DataGridTableStyle.DataGrid.Font, foreBrush, rect, format);
format.Dispose();
} // PaintText
} // DataGridLookupColumn
#endregion
DataGridComboBox#region DataGridComboBox
//**********************************************************************************************
// DataGridComboBox
//**********************************************************************************************
public class DataGridComboBox : ComboBox
{
private const int WM_KEYUP = 0x101;
protected override void WndProc(ref System.Windows.Forms.Message message)
{
// Ignore keyup to avoid problem with tabbing and dropdown list.
if (message.Msg == WM_KEYUP)
{
return;
}
base.WndProc(ref message);
} // WndProc
public string GetValueText(int index)
{
// Validate the index.
if ((index < 0) && (index >= base.Items.Count))
throw new IndexOutOfRangeException("Invalid index.");
// Get the text.
string text = string.Empty;
int memIndex = -1;
try
{
base.BeginUpdate();
memIndex = base.SelectedIndex;
base.SelectedIndex = index;
text = base.SelectedValue.ToString();
base.SelectedIndex = memIndex;
}
catch
{
}
finally
{
base.EndUpdate();
}
return text;
} // GetValueText
public string GetDisplayText(int index)
{
// Validate the index.
if ((index < 0) && (index >= base.Items.Count))
throw new IndexOutOfRangeException("Invalid index.");
// Get the text.
string text = string.Empty;
int memIndex = -1;
try
{
base.BeginUpdate();
memIndex = base.SelectedIndex;
base.SelectedIndex = index;
text = base.SelectedItem.ToString();
base.SelectedIndex = memIndex;
}
catch
{
}
finally
{
base.EndUpdate();
}
return text;
} // GetDisplayText
public string GetDisplayText(object value)
{ //mdified by zendyhu 2004-12 to fixed bug when the getValueByID
string text1 = this.ValueMember;
if (text1.Equals(string.Empty))
return "";
if (DataSource == null)
return "";
if (!(DataSource is IList))
{
return "";
}
foreach(object obj in (IList)DataSource)
{
object obj2 = FilterItemOnProperty(obj,text1);
if(value.ToString().Trim().ToUpper() == obj2.ToString().Trim().ToUpper())
{
return GetItemText(obj);
}
}
return "";
// Get the text.
// string text = string.Empty;
// int memIndex = -1;
// try
// {
// base.BeginUpdate();
// memIndex = base.SelectedIndex;
// base.SelectedValue = value;
// text = base.Text.ToString();
// base.SelectedIndex = memIndex;
// }
// catch
// {
// }
// finally
// {
// base.EndUpdate();
// }
//
// return text;
} // GetDisplayText
public string[] GetDisplayText()
{
// Get the text.
string[] text = new string[base.Items.Count];
int memIndex = -1;
try
{
base.BeginUpdate();
memIndex = base.SelectedIndex;
for (int index = 0; index < base.Items.Count; index++)
{
base.SelectedIndex = index;
text[index] = base.SelectedItem.ToString();
}
base.SelectedIndex = memIndex;
}
catch
{
}
finally
{
base.EndUpdate();
}
return text;
} // GetDisplayText
} // DataGridComboBox
#endregion
