Archived discussions · Captured October 28, 2026

How to subclass ColumnDataSource

lukas.schranglApr 10, 2017 #1

Hi,

I want to subclass ColumnDataSource. However, when trying to use this source for plotting (in a jupyter notebook), I get

Javascript error adding output!

Error:
Model `NbColumnDataSource’ does not exist. This could be due to a widget or a custom model not being registered before first usage.

See your browser Javascript console for more details.

The subclass definition is as simple as possible (for now),

class NbColumnDataSource(bokeh.models.ColumnDataSource):

pass

Is there a trick to subclassing? When looking at the source code for the source included in bokeh I colud not see one…

Best,
Lukas

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Mateusz_Paprocki3Apr 10, 2017 #2

Hi,

···

On Mon, Apr 10, 2017 at 11:00 AM, lukas.schrangl@tuwien.ac.at wrote:

Hi,

I want to subclass ColumnDataSource. However, when trying to use this source for plotting (in a jupyter notebook), I get

Javascript error adding output!

Error:
Model `NbColumnDataSource’ does not exist. This could be due to a widget or a custom model not being registered before first usage.

See your browser Javascript console for more details.

The subclass definition is as simple as possible (for now),

class NbColumnDataSource(bokeh.models.ColumnDataSource):

pass

Is there a trick to subclassing? When looking at the source code for the source included in bokeh I colud not see one…

every model in bokeh has to have a corresponding model implementation in bokehjs. You can override this behavior by implementing NbColumnDataSource as:

class NbColumnDataSource(bokeh.models.ColumnDataSource):

subtype = “NbColumnDataSource”

view_model = “ColumnDataSource”

…

This is how e.g. Figure model is implemented (see bokeh.plotting.figure). I’m pretty sure you won’t be able to add new properties to a model if it’s implemented like this.

Mateusz

Best,
Lukas

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BryanApr 10, 2017 #3

Lukas,

Can you elaborate on what you are trying to accomplish? If you want new BokehJS behaviour, then you'd provide a JS implementation as described in:

Extending Bokeh — Bokeh 0.12.5 documentation

but then you would not need the technique Mateusz mentions with "__subtype__". That technique is useful when you want to re-use a BokehJS implementation but want to add some new capability to the python side model only. I don't see what could ever be useful about a model subclass that just has "pass" as the entire body.

Thanks,

Bryan

···

On Apr 10, 2017, at 09:12, Mateusz Paprocki <mpaprocki@continuum.io> wrote:

Hi,

On Mon, Apr 10, 2017 at 11:00 AM, <lukas.schrangl@tuwien.ac.at> wrote:
Hi,

I want to subclass ColumnDataSource. However, when trying to use this source for plotting (in a jupyter notebook), I get

Javascript error adding output!
Error: Model `NbColumnDataSource' does not exist. This could be due to a widget or a custom model not being registered before first usage.
See your browser Javascript console for more details.

The subclass definition is as simple as possible (for now),

class NbColumnDataSource(bokeh.models.ColumnDataSource):
pass

Is there a trick to subclassing? When looking at the source code for the source included in bokeh I colud not see one…

every model in bokeh has to have a corresponding model implementation in bokehjs. You can override this behavior by implementing NbColumnDataSource as:

class NbColumnDataSource(bokeh.models.ColumnDataSource):
    __subtype__ = "NbColumnDataSource"
    __view_model__ = "ColumnDataSource"

   ...

This is how e.g. Figure model is implemented (see bokeh.plotting.figure). I'm pretty sure you won't be able to add new properties to a model if it's implemented like this.

Mateusz

Best,
Lukas

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lukas.schranglApr 10, 2017 #4

Hi,

Lukas,

Can you elaborate on what you are trying to accomplish?

I just wanted to modify init to call a custom function but otherwise the class should behave exactly like ColumnDataSource. Mateusz’ solution works perfectly for that.

Thanks a lot,
Lukas

···

Am Montag, 10. April 2017 16:19:31 UTC+2 schrieb Bryan Van de ven:

If you want new BokehJS behaviour, then you’d provide a JS implementation as described in:
    [http://bokeh.pydata.org/en/0.12.5/docs/user_guide/extensions.html](http://bokeh.pydata.org/en/0.12.5/docs/user_guide/extensions.html)
but then you would not need the technique Mateusz mentions with “subtype”. That technique is useful when you want to re-use a BokehJS implementation but want to add some new capability to the python side model only. I don’t see what could ever be useful about a model subclass that just has “pass” as the entire body.

Thanks,

Bryan

On Apr 10, 2017, at 09:12, Mateusz Paprocki mpap...@continuum.io wrote:

Hi,

On Mon, Apr 10, 2017 at 11:00 AM, lukas.s...@tuwien.ac.at wrote:

Hi,

I want to subclass ColumnDataSource. However, when trying to use this source for plotting (in a jupyter notebook), I get

Javascript error adding output!

Error: Model `NbColumnDataSource’ does not exist. This could be due to a widget or a custom model not being registered before first usage.

See your browser Javascript console for more details.

The subclass definition is as simple as possible (for now),

class NbColumnDataSource(bokeh.models.ColumnDataSource):

pass

Is there a trick to subclassing? When looking at the source code for the source included in bokeh I colud not see one…

every model in bokeh has to have a corresponding model implementation in bokehjs. You can override this behavior by implementing NbColumnDataSource as:

class NbColumnDataSource(bokeh.models.ColumnDataSource):
__subtype__ = "NbColumnDataSource"
__view_model__ = "ColumnDataSource"
…

This is how e.g. Figure model is implemented (see bokeh.plotting.figure). I’m pretty sure you won’t be able to add new properties to a model if it’s implemented like this.

Mateusz

Best,

Lukas

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lukas.schranglApr 10, 2017 #5

Hi,

Hi,

Hi,

I want to subclass ColumnDataSource. However, when trying to use this source for plotting (in a jupyter notebook), I get

Javascript error adding output!

Error:
Model `NbColumnDataSource’ does not exist. This could be due to a widget or a custom model not being registered before first usage.

See your browser Javascript console for more details.

The subclass definition is as simple as possible (for now),

class NbColumnDataSource(bokeh.models.ColumnDataSource):

pass

Is there a trick to subclassing? When looking at the source code for the source included in bokeh I colud not see one…

every model in bokeh has to have a corresponding model implementation in bokehjs. You can override this behavior by implementing NbColumnDataSource as:

class NbColumnDataSource(bokeh.models.ColumnDataSource):

subtype = “NbColumnDataSource”

view_model = “ColumnDataSource”

…

This is how e.g. Figure model is implemented (see bokeh.plotting.figure). I’m pretty sure you won’t be able to add new properties to a model if it’s implemented like this.

That’s all I need. It works perfectly. Thank you very much!

Lukas

···

Am Montag, 10. April 2017 16:12:47 UTC+2 schrieb mateusz.paprocki:

On Mon, Apr 10, 2017 at 11:00 AM, lukas.s...@tuwien.ac.at wrote:

Mateusz

Best,
Lukas

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systemJul 21, 2021 #6

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