Persisting Custom Objects

You do not need to implement custom persistence for the custom objects that you create as long as their properties use only simple data types such as integer and string. The default implementation of persistence saves the metadata for your object along with the values of all its properties.

However, if your object has properties that use complex data types, or if you want to perform custom processing on property values as they are loaded and saved, you can implement the IDTSComponentPersist interface and its LoadFromXML and SaveToXML methods. In these methods you load from (or save to) the XML definition of the package an XML fragment that contains the properties of your object and their current values. The format of this XML fragment is not defined; it must only be well-formed XML.

Important

When you implement custom persistence, you must persist all the properties of the object, including both inherited properties and custom properties that you have added.

Example

Although the Sql Server Custom Connection Manager Sample does not require custom persistence for its three properties of type string, the following code shows an example of the custom code that would be required to persist the connection manager and its properties. The class that contains this code must implement the IDTSComponentPersist interface.

Private Const PERSIST_ELEMENT As String = "SqlConnectionManager"  
Private Const PERSIST_SERVER As String = "Server"  
Private Const PERSIST_DATABASE As String = "Database"  
Private Const PERSIST_CONNECTIONSTRING As String = "ConnectionString"  

Public Sub LoadFromXML(ByVal node As System.Xml.XmlElement, _  
  ByVal infoEvents As Microsoft.SqlServer.Dts.Runtime.IDTSInfoEvents) _  
  Implements Microsoft.SqlServer.Dts.Runtime.IDTSComponentPersist.LoadFromXML  

  Dim propertyNode As XmlNode  

  ' Make sure that the correct node is being loaded.  
  If node.Name <> PERSIST_ELEMENT Then  
    Throw New Exception("Persisted element is not of type " & PERSIST_ELEMENT)  
  End If  

  ' Load the three properties of the object from XML into variables.  
  For Each propertyNode In node.ChildNodes  
    Select Case propertyNode.Name  
      Case PERSIST_SERVER  
        _serverName = propertyNode.InnerText  
      Case PERSIST_DATABASE  
        _databaseName = propertyNode.InnerText  
      Case PERSIST_CONNECTIONSTRING  
        _connectionString = propertyNode.InnerText  
    End Select  
  Next  

End Sub  

Public Sub SaveToXML(ByVal doc As System.Xml.XmlDocument, _  
  ByVal infoEvents As Microsoft.SqlServer.Dts.Runtime.IDTSInfoEvents) _  
  Implements Microsoft.SqlServer.Dts.Runtime.IDTSComponentPersist.SaveToXML  

  Dim elementRoot As XmlElement  
  Dim propertyNode As XmlNode  

  ' Create a new node to persist the object and its properties.  
  elementRoot = doc.CreateElement(String.Empty, PERSIST_ELEMENT, String.Empty)  

  ' Save the three properties of the object from variables into XML.  
  propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_SERVER, String.Empty)  
  propertyNode.InnerText = _serverName  
  elementRoot.AppendChild(propertyNode)  

  propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_DATABASE, String.Empty)  
  propertyNode.InnerText = _databaseName  
  elementRoot.AppendChild(propertyNode)  

  propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_CONNECTIONSTRING, String.Empty)  
  propertyNode.InnerText = _connectionString  
  elementRoot.AppendChild(propertyNode)  

  doc.AppendChild(elementRoot)  

End Sub  
private const string PERSIST_ELEMENT = "SqlConnectionManager";  
private const string PERSIST_SERVER = "Server";  
private const string PERSIST_DATABASE = "Database";  
private const string PERSIST_CONNECTIONSTRING = "ConnectionString";  

public void LoadFromXML(System.Xml.XmlElement node,  
  Microsoft.SqlServer.Dts.Runtime.IDTSInfoEvents infoEvents)  
{  

  // Make sure that the correct node is being loaded.  
  if (node.Name != PERSIST_ELEMENT)  
  {  
    throw new Exception("Persisted element is not of type " + PERSIST_ELEMENT);  
  }  

  // Save the three properties of the object from variables into XML.  
  foreach (XmlNode propertyNode in node.ChildNodes)  
  {  
    switch (propertyNode.Name)  
    {  
      case PERSIST_SERVER:  
        _serverName = propertyNode.InnerText;  
        break;  
      case PERSIST_DATABASE:  
        _databaseName = propertyNode.InnerText;  
        break;  
      case PERSIST_CONNECTIONSTRING:  
        _connectionString = propertyNode.InnerText;  
        break;  
    }  
  }  

}  

public void SaveToXML(System.Xml.XmlDocument doc,  
  Microsoft.SqlServer.Dts.Runtime.IDTSInfoEvents infoEvents)  
{  

  XmlElement elementRoot;  
  XmlNode propertyNode;  

  // Create a new node to persist the object and its properties.  
  elementRoot = doc.CreateElement(String.Empty, PERSIST_ELEMENT, String.Empty);  

  // Save the three properties of the object from variables into XML.  
  propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_SERVER, String.Empty);  
  propertyNode.InnerText = _serverName;  
  elementRoot.AppendChild(propertyNode);  

  propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_DATABASE, String.Empty);  
  propertyNode.InnerText = _databaseName;  
  elementRoot.AppendChild(propertyNode);  

  propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_CONNECTIONSTRING, String.Empty);  
  propertyNode.InnerText = _connectionString;  
  elementRoot.AppendChild(propertyNode);  

  doc.AppendChild(elementRoot);  

}  

See Also

Developing Custom Objects for Integration Services
Building, Deploying, and Debugging Custom Objects