[FEATURE] Exporting tables as CSVs

[Vel-San]

Is your feature request related to a problem? Please describe.
Not a Problem per say, but i do need this almost everytime i use Bokeh.

Describe the solution you'd like
I've seen a lot of JS hacks to export table data as CSV in Bokeh, but i think just like we have a 'Save' toolbar button for graphs it would be great to also have a save button or export for tables too.

Describe alternatives you've considered
Using JS scripts and binding to Button widgets, but isn't always consistant.

[bryevdv]

@Vel-San The issue is that I don't really know how to make anything better than the example in the repo, which as you note, not perfect. This is why I have been more inclined to see it as an illustrative and hopefully useful example, but not something robust enough to add to the library proper.

I would say adding anything directly to the DataTable itself is also very unlikely. The DataTable implementation is based on a large third party library, that we only vendor in order to smooth out some build issues. We don't have the resources to take on direct modification and maintenance of such a large external component. It's also the case that there are times when it would be relevant to download a CSV even without a table present in the Document at all, so tying things to only the Datatable would be needlessly limiting. Much more likely would be something like a "canned" CustomJS action that is easily to attach to a button or toolbar or wherever with a single operation.

But first there would have to be a completely robust implementation that is tested to work correctly across (linux, osx, windows) x (chrome, firefox, safari, ie, edge, ...) If you have any pointers or links to anything useful we could certainly take a look.