Silverlight: 为ComboBox实现SelectedValue属性
silverlight中的comboBox并不像一般asp.net的dropdownlist或winform中的comboBox,有selectedValue属性。因为在silverlight中使用comboBox使用selectedItem就基本上满足了需求，如果还不够可以再为相应Tag赋值就OK了。
下面主要说一下为comboBox扩展一个selectedValue属性，其实也很简单，只要为ComboBox注册一个就OK。
1. 一个简单的效果图：
2. 调用方法:
代码
ComboBoxItemValueExtend cbmValueExtend
=
new
ComboBoxItemValueExtend();
cbmValueExtend.SelectionChanged
+=
(sender, arg)
=>
{
UI.Alert(cbmValueExtend.SelectedValue);
};
cbmValueExtend.ItemsSource
=
DepartmentDataSource();
cbmValueExtend.DisplayMemberPath
=
"
Name
"
;
cbmValueExtend.SelectedValuePath
=
"
ID
"
;
Dialog dlg
=
new
Dialog()
{
Height
=
300
,
Width
=
400
,
Title
=
"
ComboBox's SelectedValue Sample
"
,
Content
=
new
AutoGrid(
3
,
60
,
180
)
{
Children
=
{
new
Label(){Content
=
"
请选择：
"
},
cbmValueExtend
}
}
};
dlg.Show();
3. ComboBoxItemValueExtend的实现代码
代码
using
System;
using
System.Net;
using
System.Windows;
using
System.Windows.Controls;
using
System.Windows.Documents;
using
System.Windows.Ink;
using
System.Windows.Input;
using
System.Windows.Media;
using
System.Windows.Media.Animation;
using
System.Windows.Shapes;
using
System.Linq;
namespace
Top.Windows.Settings
{
public
class
ComboBoxItemValueExtend : ComboBox
{
#region
DependencyProperty: SelectedValuePathProperty-----------------------------------------
public
static
readonly
DependencyProperty SelectedValuePathProperty
=
DependencyProperty.Register(
"
SelectedValuePath
"
,
typeof
(
string
),
typeof
(ComboBoxItemValueExtend),
null
);
///
<summary>
///
Set the name or path of the property that is value for each date item.
///
</summary>
public
string
SelectedValuePath
{
get
{
return
(
string
)GetValue(ComboBoxItemValueExtend.SelectedValuePathProperty);
}
set
{
SetValue(ComboBoxItemValueExtend.SelectedValuePathProperty, value);
}
}
#endregion
DependencyProperty: SelectedValuePathProperty-----------------------------------------
#region
DependencyProperty: SelectedValueProperty-------------------------------------
public
static
DependencyProperty SelectedValueProperty
=
DependencyProperty.Register(
"
SelectedValue
"
,
typeof
(
object
),
typeof
(ComboBoxItemValueExtend),
new
PropertyMetadata(
new
PropertyChangedCallback(SelectedValuePropertyChanged)));
///
<summary>
///
Get Selected Value in the comboBox's SelectedItme
///
</summary>
public
object
SelectedValue
{
get
{
return
GetValue(SelectedValueProperty);
}
set
{
try
{
var q
=
(from item
in
Items
where
item.GetType().GetProperty(SelectedValuePath).GetValue(item,
null
).Equals(value)
select item).Single();
SelectedItem
=
q;
}
catch
{
throw
new
Exception();
}
}
}
private
static
void
SelectedValuePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
(d
as
ComboBoxItemValueExtend).SelectedValue
=
e.NewValue;
}
#endregion
DependencyProperty: SelectedValueProperty-------------------------------------
public
ComboBoxItemValueExtend()
:
base
()
{
base
.SelectionChanged
+=
new
SelectionChangedEventHandler(ComboBoxItemValueExtend_SelectionChanged);
}
void
ComboBoxItemValueExtend_SelectionChanged(
object
sender, SelectionChangedEventArgs e)
{
if
(SelectedItem
!=
null
&&
!
string
.IsNullOrEmpty(SelectedValuePath))
{
try
{
SetValue(ComboBoxItemValueExtend.SelectedValueProperty, SelectedItem.GetType().GetProperty(SelectedValuePath).GetValue(SelectedItem,
null
));
var value
=
SelectedValue;
}
catch
{
throw
new
Exception();
}
}
}
}
}
4. DepartmentDataSource()方法是获取一些测试数据
代码
public
struct
Department
{
public
int
ID {
set
;
get
; }
public
int
ParentId {
set
;
get
; }
public
string
Name {
set
;
get
; }
public
string
Description {
set
;
get
; }
}
public
List
<
Department
>
DepartmentDataSource()
{
List
<
Department
>
list
=
new
List
<
Department
>
() {
new
Department(){ID
=
1
, ParentId
=
0
, Name
=
"
Namespace
"
},
new
Department(){ID
=
2
, ParentId
=
1
, Name
=
"
Class
"
},
new
Department(){ID
=
3
, ParentId
=
1
, Name
=
"
Enum
"
},
new
Department(){ID
=
4
, ParentId
=
2
, Name
=
"
Method
"
},
new
Department(){ID
=
5
, ParentId
=
4
, Name
=
"
Attribute
"
},
new
Department(){ID
=
6
, ParentId
=
5
, Name
=
"
Private
"
},
new
Department(){ID
=
7
, ParentId
=
5
, Name
=
"
Publict
"
},
new
Department(){ID
=
8
, ParentId
=
7
, Name
=
"
DepartmentDataSource()
"
},
};
return
list;
}
谢谢指导！
备注：
关于DependencyProperty的相关知道可以翻阅MSDN学习一下，里面有详细的介绍，这里不再复述！
http://msdn.microsoft.com/zh-cn/library/cc221408.aspx