Adding a layout shape line with custom dash lenght lists is not working

[dvd7587]

Example:
plotly.graph_objects.layout.shape.Line(color='black', width=2, dash='5px,3px,3px,2px')

produces the following:

ValueError: 
    Invalid value of type 'builtins.str' received for the 'dash' property of layout.shape.line
        Received value: '5px,3px,3px,2px'

    The 'dash' property is a string and must be specified as:
      - One of the following strings:
            ['solid', 'dot', 'dash', 'longdash', 'dashdot',
            'longdashdot']
      - A number that will be converted to a string

Moreover, the documentation and the Line docstring state that it should be allowed, but the layout.shape.Line.dash property docstring states otherwise.

[kvanderwijst]

Had the same issue. After looking around a bit, I found that the problem is that the DashValidator from validators/layout/shape/line inherits from StringValidator instead of DashValidator (same actually for validators/scattersmith/line and validators/layout/newshape/line). Changing this line:

class DashValidator(_plotly_utils.basevalidators.StringValidator):

to this:

class DashValidator(_plotly_utils.basevalidators.DashValidator):

in the file C:\Users\[USER]\Anaconda3\Lib\site-packages\plotly\validators\layout\shape\line\_dash.py on Windows (probably similar on Linux/Mac) fixes the issue. Not sure how to make a patch of this though.