[BUG] select(CategoricalColorMapper) returns an empty array

[vanHekthor]

Software versions

Python version : 3.8.16 | packaged by conda-forge | (default, Feb 1 2023, 16:01:55)
IPython version : 8.11.0
Tornado version : 6.2
Bokeh version : 3.1.0
BokehJS static path : /home/[user]/git/chartify/.conda/lib/python3.8/site-packages/bokeh/server/static
node.js version : v18.14.2
npm version : 9.5.0
Operating system : Linux-5.15.90.1-microsoft-standard-WSL2-x86_64-with-glibc2.10

Browser name and version

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Jupyter notebook / Jupyter Lab version

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Expected behavior

In case of the code example that is attached, p.select(CategoricalColorMapper) should return an instance of CategoricalColorMapper.

Observed behavior

Instead an empty array [] is returned.

Example code

from bokeh.plotting import figure, show
from bokeh.sampledata.penguins import data
from bokeh.transform import factor_cmap, factor_mark
from bokeh.models import CategoricalColorMapper

SPECIES = sorted(data.species.unique())
MARKERS = ['hex', 'circle_x', 'triangle']

p = figure(title = "Penguin size", background_fill_color="#fafafa")

p.scatter("flipper_length_mm", "body_mass_g", source=data,
          legend_group="species", fill_alpha=0.4, size=12,
          marker=factor_mark('species', MARKERS, SPECIES),
          color=factor_cmap('species', 'Category10_3', SPECIES))

print(p.select(CategoricalColorMapper)) # output: []

(provided by Bryan)

Stack traceback or browser console output

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Screenshots

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[bryevdv]

@mattpap it seems possible that when Field was added, that select etc were not taught how to handle them, since in the above code:

In [17]: p.renderers[0].glyph.fill_color

Out[17]: Field(field='species', transform=CategoricalColorMapper(id='p1049', ...), units=Unspecified)

tentatively triaged with python but we should make sure it does not affect the BokehJS select as well.