Supply url_fetcher to weasyprint to support /media and /static files

[LqdBcnAtWork]

Pull request with changes from a comment made on #9351.

This allows weasyprint to grab files from /media and /static locations by redirecting them to open() calls with respect to MEDIA_ROOT and STATIC_ROOT settings.

Probably could be made better. But at least ensures that the resulting path is always still a child of the parent folder.

[netlify]

✅ Deploy Preview for inventree-web-pui-preview canceled.

Name	Link
🔨 Latest commit	c55c53a
🔍 Latest deploy log	https://app.netlify.com/sites/inventree-web-pui-preview/deploys/67e459500d4d47000802ac1b

[SchrodingersGat]

@LqdBcnAtWork FYI there are already template tags available to the reporting system for displaying uploaded images:

• https://docs.inventree.org/en/stable/report/helpers/#media-files
• https://docs.inventree.org/en/stable/report/helpers/#uploaded_image
• https://docs.inventree.org/en/stable/report/helpers/#encode_svg_image
• https://docs.inventree.org/en/stable/report/helpers/#part_image
• https://docs.inventree.org/en/stable/report/helpers/#company_image
• https://docs.inventree.org/en/stable/report/helpers/#report-assets

[SchrodingersGat]

An issue here is that the request URL may or may not exactly match the server's internal URL, depending on proxying settings. Adding a hard-coded URL here is not a good idea.

[LqdBcnAtWork]

Just a clarifying question, would it be possible to use these somehow with markdownify?

That was the "problem" this code was meant to solve. The notes editor uses relative paths (eg: /media/notes/image.png) for the SRC attribute. Which markdownify uses without transformation.

This pull request makes it so weasyprint can grab those images as well for pdf generation. Currently images aren't included when notes are transformed into html by markdownify, as weasyprint has no method of getting the assets. It actually throws an error as there are relative paths with no base path provided.

[SchrodingersGat]

@LqdBcnAtWork yeah I definitely appreciate what you are trying to achieve here. Having another read through, this might not be a terrible idea ;)

• You upload an image into the notes for a part, which then loads an image against /media/images/my_image.png
• When you try to render the same markdown into HTML (for weasyprint report rendering) it fails because it doesn't know how to access the image
• Add a custom fetcher to weasyprint which supports just /media/ and /static/ requests
• This works not just for markdown code, but any HTML we want to render into the report

So, there are still some issues to deal with here:

1. Remove the hard-coded URL prefix - should use the defined site_url
2. Can we support lookup of assets without a HOST prefix e.g. /media/images/my_image.png vs http://server.com/media/images/my_image.png
3. We need to be able to support other types of django storage backends - not just filesystem storage

[matmair]

Let us know if you want pointers how the requested changes might be achieved

[SchrodingersGat]

@LqdBcnAtWork are you still looking into this?

[LqdBcnAtWork]

My apologies, I am still planning on doing more on this. But I've been pulled aside to other projects for the time being.

I'll get back to this eventually. It's becoming a conversation of when, not if, we'll switch to Inventree.