WebPart.AfterDeserialize 方法
从 SharePoint 数据库或 Web 部件描述文件 （.dwp) SharePoint Web 部件的属性反序列化之后调用。SharePoint Web 部件升级代码的的建议的位置。
命名空间： Microsoft.SharePoint.WebPartPages
程序集： Microsoft.SharePoint（位于 Microsoft.SharePoint.dll 中）
语法
声明
Public Overridable Sub AfterDeserialize
用法
Dim instance As WebPart
instance.AfterDeserialize()
public virtual void AfterDeserialize()
备注
AfterDeserialize方法支持 Web 部件的新版本需要适应对已保存的以前版本的 Web 部件的属性的更改的升级方案。如果 Web 部件开发人员只需将添加一个或多个新属性，不所需的任何升级的逻辑。但是，如果属性被删除或重命名，或保存的值发生了变化，然后重写AfterDeserialize方法提供一种方法，用于处理这些更改时 SharePoint Web 部件升级。
示例
下面的代码示例演示如何从 Web 部件的更高版本中删除了一个或多个属性时处理情况。由于该程序集无法识别的元素将添加到UnknownXmlElementCollection集合，下面的代码示例显示循环访问该集合并删除未知的元素。
有关在升级 Web 部件，使用AfterDeserialize方法的详细信息，请参阅升级 Web 部件程序集。
' Override the AfterDeserialize method to remove any items in
' the UnknownXmlElementCollection within the MyWebPartNamespace
Public Overrides Sub AfterDeserialize()
Try
Dim itemsRemoved As Boolean = False
If UnknownXmlElements.Count > 0 Then
Dim element As XmlElement
Dim index As Integer = UnknownXmlElements.Count - 1
' Loop from the end of the collection to eliminate the need to
' update the index based on whether or not an item was deleted.
While index >= 0
element = UnknownXmlElements(index)
' Check if the element is within the namespace.
' Do a case-insensitive match to be consistent with the
' XmlSerializer.
If element.NamespaceURI = "MyWebPartNamespace" Then
' If the element is in the namespace, remove it
' from the collection.
UnknownXmlElements.RemoveAt(index)
itemsRemoved = True
End If
index -= 1
End While
End If
' If your assembly is installed in the application's bin directory, which defaults to minimal trust,
' make sure that your Web Part assembly has UnsafeSaveOnGet permission or the following
' attempt to save changes will return an error.
If itemsRemoved Then
SaveProperties = True
End If
Catch Else
' Handle or ignore errors.
End Try
End Sub
// Override the AfterDeserialize method to remove any items in
// the UnknownXmlElementCollection within the MyWebPartNamespace
public override void AfterDeserialize()
{
try
{
bool itemsRemoved = false;
if (UnknownXmlElements.Count>0)
{
XmlElement element;
int index = UnknownXmlElements.Count - 1;
// Loop from the end of the collection to eliminate the need to
// update the index based on whether or not an item was deleted.
while (index >= 0)
{
element = UnknownXmlElements[index];
// Check if the element is within the namespace.
// Do a case-insensitive match to be consistent with the
// XmlSerializer.
if (element.NamespaceURI == "MyWebPartNamespace")
{
// If the element is in the namespace, remove it from the collection.
UnknownXmlElements.RemoveAt(index);
itemsRemoved = true;
}
--index;
}
}
// If your assembly is installed in the application's bin directory, which defaults to minimal trust,
// make sure that your Web Part assembly has UnsafeSaveOnGet permission or the following
// attempt to save changes will return an error.
if (itemsRemoved)
{
SaveProperties = true;
}
}
catch
{
// Handle or ignore errors.
}
}