Facing problem on External Object Drag Event

Hello to all

I am a new GoProgrammer. I make an application as shown in picture below.when I drag a network element from left pane to right pane there are fillowing error show.
Can you please suggest where i am wrong.
I attched the code where this error shows.
Please suggest me It is Very urgent
private void myView_ExternalObjectsDropped(object sender, GoInputEventArgs e) {

SqlConnection conn = new SqlConnection(strCon);

GraphNode ParentNode = myView.PickObject(true, false, myView.LastInput.DocPoint, true) as GraphNode;
string strQuery = "INSERT INTO provision(provision_name,capacity_id,status_type_id,update_dt,insert_dt,last_user) "

  • “values(’” + ParentNode.Text.Trim() + “’,” + ParentNode.ImageID + “,1,’” + DateTime.Now + “’,’” + DateTime.Now + “’,‘cadebill’)”;
    SqlCommand Comm = new SqlCommand(strQuery, conn);
    int result = Comm.ExecuteNonQuery();
    catch (Exception ex)


You should be able to debug this with Visual Studio. My guess is that your “ParentNode” variable is null.

That’s because the user didn’t perform the drop onto a node. Why? At least two possibilities:

(1) the drop happened where there wasn’t any object in the document, or
(2) the drop happened on a part of the node, not on the whole node.

You need to handle both cases. I can’t tell you what to do for (1), but for (2), I suggest you do:

GoObject obj = myView.PickObject(true, false, e.DocPoint, true);

if (obj == null) {

... // didn't drop on top of a document object

} else {

GraphNode node = obj.ParentNode as GraphNode;

if (node != null) {

... // dropped onto (part of) a GraphNode

} else {

... // dropped onto a link?



Thanx Walter for quick reply.