add "Quick Fix"/"Code Action" implementation example to Language Server Extension Guide

[hamirmahal]

https://code.visualstudio.com/api/language-extensions/language-server-extension-guide has detailed documentation on simple validation and publishing diagnostics: https://code.visualstudio.com/api/language-extensions/language-server-extension-guide#adding-a-simple-validation.

It would be really helpful if the documentation could also show the "correct" way, if such a thing exists, to communicate between the client and server when there is an appropriate "Quick Fix" or "Code Action" for a diagnostic.

For instance, in the example, we add diagnostics for words that have more than two uppercase letters. Even just documentation describing how to do something simple, like converting those words to lowercase, or deleting those words, would be very instructive.

To be specific, it would be extremely helpful to know what code to write in extension.ts and server.ts to achieve that functionality.

@dbaeumer I'd be more than happy to write, proofread, and contribute documentation for this, if you could describe to me the steps, both at a high-level, and low-level, meaning in terms of the actual code, on how to add basic "Quick Fix" and "Code Action" functionality.

@rictic has a very helpful comment in microsoft/language-server-protocol#144, but it provides a high-level overview, and not the specific code to write in server.ts and extension.ts.

@kdvolder also created a Stack Overflow post regarding this topic: https://stackoverflow.com/questions/43328582/how-to-implement-quickfix-via-a-language-server. It is also useful, but it, too, provides a high-level overview, and not code examples to implement the "Quick Fix" functionality. There's a corresponding issue in microsoft/language-server-protocol#219.

[KamasamaK]

The repo for VS Code documentation such as that guide is https://github.com/microsoft/vscode-docs.

[dbaeumer]

@hamirmahal I would start with the implementation which can be done here: https://github.com/microsoft/vscode-extension-samples.git in the folder lsp-sample.

If we have the sample we can check if we need to add this to the doc or if the code is enough.

[hamirmahal]

@dbaeumer Thanks for the reply!

I looked at a folder adjacent to lsp-sample, https://github.com/microsoft/vscode-extension-samples/tree/main/lsp-user-input-sample, and it was very helpful in learning how Code Action population works.

I think that example suffices and there's no need to "reinvent the wheel" by writing documentation that explains how Code Action communication works in https://code.visualstudio.com/api/language-extensions/language-server-extension-guide.

In case it helps anyone who comes across this in a search in the future, I was able to get my connection.onCodeAction( in server.ts to actually be able to receive client Code Action requests by adding codeActionProvider: true, as a property to the server's capabilities object in connection.onInitialize(() => { in server.ts. Hope it helps!