All preferences and offline data for DevDocs are lost after VSCode restart

[volo-zyko]

As far as I understand this is restriction imposed by vscode.previewHtml but still it has to be tackled somehow. Either vscode.previewHtml has to be extended/superseded (that's on VSCode side) or DevDocs settings has to be saved externally (on vscode-devdocs side) and passed to DevDocs when it's opened.

This is really annoying issue and is a showstopper for me. :(

[sagaban]

I have the same issue :( Are you open to PR?

[jcw-]

It does not appear to currently be possible to do this because:

1. VS Code's previewHtml uses an Electron webview with a non-persistent session. This is because it specifies a partition name without a persist: prefix and avoids using the default (persistent) partition. This means the webview persists in-memory and is lost when VS Code is restarted.
2. There does not appear to be any way to use a persistent webview in VS Code.
3. The technique used by this extension is to load HTML containing an iframe pointing to devdocs.io. However, it is not possible to modify the contents of the iframe (e.g. to try and manually import/set preferences) due to cross-frame scripting security (this is a good thing). Any import/export or setting of preferences on the iframe would need to use an interface exposed by devdocs.io - and there isn't such a thing (not such a good thing). One option would be for devdocs to call a parent method (if it exists) to allow for the opportunity to override preferences, which could then be defined in this extension's HTML file.
4. Modifying where devdocs.io stores the preferences is also not really an option, as it uses a cookie to hold this data.

Workarounds:

• Use a tool such as Fiddler or Wireshark to inject the pre-configured cookie into the network communication between VS Code and devdocs.io.
• Run devdocs.io locally and modify the code so that the defaults match what you actually want, run it locally using rvmsudo bundle exec rackup -p 80 -o 0.0.0.0 and serve it instead of devdocs.io by leveraging etc/hosts. This is the option I ended up going with.

[cstuder]

That's too bad.

Another idea: Devdocs.io is open source, we could suggest a feature in which the initial configuration can be transmitted JSON encoded by pseudo-GET-parameter or in the hash part of the URI. Devdocs.io would then have to import the parameters during the initial load (As if the user had just 'imported' the setttings.)

This would shift the initial configuration into vscode-devdocs settings. Unfortunately this would mean that you would have to manually update these settings when you want to change the devdocs.io settings. Syncing these settings wouldn't be possible as far as I can see. (Havin only little extension development experience.)

[cstuder]

Alternatively add an option to open the documentation in an external browser window.

[jcw-]

@cstuder Yeah, I considered the same thing, I actually looked into submitting a PR against devdocs to support non-cookie based storage of configuration, but it turned out to be a bit more complicated than I had hoped, so I didn't pursue it: freeCodeCamp/devdocs#199
Probably still within the realm of possibility though.

I'm not sure it makes sense to open anything external in this particular extension, it's pretty focused on doing it inline - there is actually a second devdocs extension that does what you describe though (opens a search in a browser).

[akfish]

I agree with what @jcw- said. I investigated some possible fixes including:

• Making devdocs stateless by passing configurations via url parameters (won't fix offline caching obviously)
• Consume devdocs database directly and use vscode's native UI

They've proven to be too much work for me and I unfortunately don't have enough free time for this.

At this time I won't recommend using this extension any more. I moved on to using dash instead. Thanks for trying it out and sorry for the inconveniences. PLs are still welcome and I'll review and merge them whenever possible.

[wmertens]

There is also https://github.com/egoist/devdocs-desktop/ which has a global hotkey

[L3v3L]

would the new move from previewHtml to webView (microsoft/vscode#62630) help in solving this issue?

[wmertens]

Hmm that needs to be done anyway since the previewHtml is deprecated. It has a retainContextWhenHidden flag that keeps the window state when the tab is not visible, which will help, but it still destroy the content when the tab is closed, which may or may not mean cached content is gone.

If devdocs has an API to manage the cache though, the extension could use that to maintain the devdocs cache. That would be 💯