write_image() doesn't work with pathlib.Path() objects

This code works as expected:

import plotly.express as px
fig = px.scatter(x=[1,2,3], y=[1,2,3])
# Works with a string
fig.write_image('test.png', format='png')

However, if you try to use a pathlib.Path object instead of a string, you get an exception:

import plotly.express as px
import pathlib
fig = px.scatter(x=[1,2,3], y=[1,2,3])
# Doesn't work with a Path
fig.write_image(pathlib.Path('test.png'), format='png')

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-6-402d35877fa7> in <module>
      6 fig.write_image('test.png', format='png')
      7 # Doesn't work with a Path
----> 8 fig.write_image(pathlib.Path('test.png'), format='png')

/opt/conda/lib/python3.8/site-packages/plotly/basedatatypes.py in write_image(self, *args, **kwargs)
   3249         import plotly.io as pio
   3250 
-> 3251         return pio.write_image(self, *args, **kwargs)
   3252 
   3253     # Static helpers

/opt/conda/lib/python3.8/site-packages/plotly/io/_kaleido.py in write_image(fig, file, format, scale, width, height, validate, engine)
    258             f.write(img_data)
    259     else:
--> 260         file.write(img_data)
    261 
    262 

AttributeError: 'PosixPath' object has no attribute 'write'

This code works, though:

import plotly.express as px
import pathlib
fig = px.scatter(x=[1,2,3], y=[1,2,3])
fig.write_image(str(pathlib.Path('test.png')), format='png')

So, at a minimum this could be fixed by checking if file is an instance of pathlib.Path and if so, cast it as a str.

PS Thanks for all the hard work on this project, it’s great watching it continually improve. This isn’t a particularly important issue for me, just wanted to add it to the list of potential fixes for the next version in case others are also interested.

[nicolaskruchten]

Support for this just came out with version 5.0 😃

[nicolaskruchten]

Thanks for the bug report and the attempted PR 😃

I wonder if there’s not a more generic solution than spot-checking for pathlib objects, like “if it’s not writeable, try to stringify it” or something like that.