Synchronizing DataTable js and python

Hi all,

I have an application with a plot and DataTable. I used one of the examples using the BoxSelectTool to add rectangles to the plot. The dimensions of the rectangles are saved to a ColumnDataSource that is displayed in the DataTable. When the DataTable is modified I save those changes and redraw the boxes.

Currently, when I draw a box it gets added to the DataTable, but no sent back to python. When I edit an entry in the table then the current state gets sent back to python.

After reading some code and GH issues I found a work-around in my CustomJS callback for the BoxSelectTool:

selected_callback = CustomJS(args=dict(source=annotations, glyphs=glyph, table=annotation_table), code="""

var geometry = cb_data[‘geometry’];

// update data source with new Rect attributes

// < omitted .push to source >

// trigger update of data source




table.source.change.emit(); =


The work-around is the = which is required to trigger the “_tell_document_about_change” in the ColumnDataSource. Ideally I could just call that function after doing the push rather than doing a meaningless copy to trigger the notification.

Is that possible? I’m not good with js, but my tinkering hasn’t found that function exposed to me.