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Archived discussions · Captured October 28, 2026

JS: monitor changes in core properties?

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ltalirz
ltalirzSep 18, 2018   #1

The helpful example for wrapping a JS library uses a bokeh.models.ColumnDataSource in order to update the graph whenever the data changes.

Can I also monitor changes in, say, a bokeh.core.properties.String or bokeh.core.properties.Dict?

I’m trying to write a JSmol bokeh extension and I’m currently just awkwardly passing things through a ColumnDataSource that don’t really belong there.

The code that does the monitoring in the example is

    # Set a listener so that when the Bokeh data source has a change
    # event, we can process the new data
    @connect(@model.data_source.change, () =>
        @_graph.setData(@get_data())
    )

``

which uses the .change property that does not seem to be available for core properties

Best,

Leopold

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Mateusz_Paprocki2
Mateusz_Paprocki2Sep 19, 2018   #2

Hi,

···

On Tue, Sep 18, 2018 at 11:28 PM, Leopold Talirz leopold.talirz@gmail.com wrote:

The helpful example for wrapping a JS library uses a bokeh.models.ColumnDataSource in order to update the graph whenever the data changes.

Can I also monitor changes in, say, a bokeh.core.properties.String or bokeh.core.properties.Dict?

I’m trying to write a JSmol bokeh extension and I’m currently just awkwardly passing things through a ColumnDataSource that don’t really belong there.

The code that does the monitoring in the example is

    # Set a listener so that when the Bokeh data source has a change
    # event, we can process the new data
    @connect(@model.data_source.change, () =>
        @_graph.setData(@get_data())
    )

``

which uses the .change property that does not seem to be available for core properties

there are two types of change signals, one for models and one for individual properties:

  1. this.connect(this.model.data_source.change, listener) will invoke the listener when the contents of the object referenced by data_source changed

  2. this.connect(this.model.properties.data_source.properties.change, listener) will invoke the listener when the value of data_source property changed

If you want to listen listen to change to a particular property of a data source (e.g. data), then you would use this.connect(this.model.data_source.properties.data.change, listener).

Mateusz

Best,

Leopold

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ltalirz
ltalirzSep 20, 2018   #3

Dear Mateusz,

thank you very much for your advice! It already simplifies things to be able to just watch the “data” property without having to re-create the whole object.

What I was trying to get at originally - do I need to use ColumnDataSource at all?

I.e. if what I would like to watch is not really columnar data but, say, a string or a dictionary, what object should I use on the python side?

As an alternative to watching, it would also be fine to add a function to the extension that can be called explicitly from the python side - could you maybe point me to an example of how to do this?

Best wishes,

Leopold

···

On Wednesday, September 19, 2018 at 2:03:16 PM UTC+2, mateusz.paprocki wrote:

Hi,

On Tue, Sep 18, 2018 at 11:28 PM, Leopold Talirz leopold...@gmail.com wrote:

The helpful example for wrapping a JS library uses a bokeh.models.ColumnDataSource in order to update the graph whenever the data changes.

Can I also monitor changes in, say, a bokeh.core.properties.String or bokeh.core.properties.Dict?

I’m trying to write a JSmol bokeh extension and I’m currently just awkwardly passing things through a ColumnDataSource that don’t really belong there.

The code that does the monitoring in the example is

    # Set a listener so that when the Bokeh data source has a change
    # event, we can process the new data
    @connect(@model.data_source.change, () =>
        @_graph.setData(@get_data())
    )

``

which uses the .change property that does not seem to be available for core properties

there are two types of change signals, one for models and one for individual properties:

  1. this.connect(this.model.data_source.change, listener) will invoke the listener when the contents of the object referenced by data_source changed
  1. this.connect(this.model.properties.data_source.properties.change, listener) will invoke the listener when the value of data_source property changed

If you want to listen listen to change to a particular property of a data source (e.g. data), then you would use this.connect(this.model.data_source.properties.data.change, listener).

Mateusz

Best,

Leopold

–

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