Since Plotly 3.5.0 i get KeyError: 'titlefont'

[Endogen]

This code worked fine until i updated to plotly 3.5.0

        fig['layout'].update(
            title=coin,
            titlefont=dict(
                size=26
            ),
            yaxis=dict(
                title=base_coin,
                titlefont=dict(
                    size=18
                )
            )
        )

But since 3.5.0 i get

File "/usr/local/lib/python3.7/site-packages/plotly/basedatatypes.py", line 3021, in update
    BaseFigure._perform_update(self, kwargs)
  File "/usr/local/lib/python3.7/site-packages/plotly/basedatatypes.py", line 2249, in _perform_update
    validator = plotly_obj._get_prop_validator(key)
  File "/usr/local/lib/python3.7/site-packages/plotly/basedatatypes.py", line 3706, in _get_prop_validator
    return super(BaseLayoutHierarchyType, self)._get_prop_validator(prop)
  File "/usr/local/lib/python3.7/site-packages/plotly/basedatatypes.py", line 2622, in _get_prop_validator
    return self._validators[prop]
KeyError: 'titlefont'

Error seems to be at this line size=18
Is this a bug or do i have to change the way i set the title font?

Here is a bit more context if needed

        fig = fif.create_candlestick(o, h, l, c, pd.to_datetime(t, unit='s'))

        fig['layout']['yaxis'].update(
            tickformat=tickformat,
            tickprefix="   ",
            ticksuffix=f"  ")

        fig['layout'].update(
            title=coin,
            titlefont=dict(
                size=26
            ),
            yaxis=dict(
                title=base_coin,
                titlefont=dict(
                    size=18
                )
            )
        )

        fig['layout'].update(
            shapes=[{
                "type": "line",
                "xref": "paper",
                "yref": "y",
                "x0": 0,
                "x1": 1,
                "y0": c[len(c) - 1],
                "y1": c[len(c) - 1],
                "line": {
                    "color": "rgb(50, 171, 96)",
                    "width": 1,
                    "dash": "dot"
                }
            }])

        fig['layout'].update(
            paper_bgcolor='rgb(233,233,233)',
            plot_bgcolor='rgb(233,233,233)',
            autosize=False,
            width=800,
            height=600,
            margin=go.layout.Margin(
                l=margin_l,
                r=50,
                b=85,
                t=100,
                pad=4
            ))

EDIT: Actually, i'm not sure if this is only an issue in 3.5.0 since i realized that i previously used 3.3.0

[jonmmease]

Hi @Endogen ,

Thanks for taking the time to report this. It looks like a backwards compatibility oversight from the port to plotly.js 1.43 (#1376) that was released in plotly.py 3.5.0. Here's a minimal reproducible example:

import plotly.graph_objs as go
fig = go.Figure()
fig['layout'].update(
    titlefont=dict(
        size=26
    ),
)

For some context, plotly.js rearranged the title* properties in version 1.43.0 and moved them under the corresponding title object. So to update the title text and font using the structure in plotly.js 1.43.0 you would do this:

import plotly.graph_objs as go
fig = go.Figure()
fig['layout'].update(
    title=dict(
        text='Title',
        font=dict(
            size=26
        )
    ),
)

So if you don't need to keep compatibility with older versions of plotly.py you can go ahead and switch to this form.

That said, the old structure should still work everywhere and it looks like we're not handling something related to the update method properly.

[Endogen]

So if you don't need to keep compatibility with older versions of plotly.py you can go ahead and switch to this form.

Ah great! I don't need any compatibility 😄 Thanks for the MWE - that should have been my job 🙈