XPages: Dynamically binding document events without breaking existing

Update 19.03.10: I rewrote the script library so that it executes the dynamically added event handlers in a queue, instead of trying to modify the expression string of the embedded event handler.

Update 29.04.10: Fixed a bug in the script. var dataSource = this.getDataSource( datasourceId );. dataSourceId was missing, resulting in only the first document data source being returned.


One of many things I miss in XPages is the possibility to dynamically bind multiple event listeners per document event (e.g. querySaveDocument). You can dynamically bind a single document event quite easy.

In beforePageLoad:

var application = facesContext.getApplication();
var methodBinding = application.createMethodBinding( '#{javascript:yourCode}', null);

// get(0) -> The first data source in the page
view.getData().get(0).setQuerySaveDocument( methodBinding );

The problem with the above code, is that if someone puts querySaveDocument code in the XPage you're setting the above event, that code is overwritten/ignored.

Here's some server side javascript that lets you add document event code without breaking existing code. I suggest running this function beforePageLoad.

Example usage (beforePageLoad):

Events.addToDocumentEvent( 'querySaveDocument', 'xspTestDoc.setValue( "description", "Overridden" )' );

If you're wondering why I'd want to bind events dynamically..

In an XPages application I'm working on, I've made a custom control that's similar to the "prevent save conflicts" custom control I wrote about a little while back.

The difference between the one I posted, and the one in the application is that it uses a custom field on the document. The field is used to test if the document has been modified by a user. When a user saves a document, the field value is set to @Now().

The custom control I wrote about earlier uses the "@Modified-value" that's set whenever a document is modified. I only want the validation to trigger when a user has modified the document/another user has the document open for editing.

The custom control in the application I'm working on dynamically adds a little querySaveDocument code so that the modified-by-user field is set when the document is saved. This code has to work alongside existing code in the querySaveDocument-event.

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I probably couldn't have written the above function without my API Inspector. If you want to hack around the limitations of Domino Designer, I suggest you take a look at it.

If you're having a hard time debugging XPages, I suggest you take a look at the Medusa project written by three wizards from Lotus911.