How to use yaml formatter with Neovim builtin LSP client?

[dhruvmanila]

The codebase contains a yamlFormatter although the server capabilities says otherwise:

        documentFormattingProvider: false,

The formatter runs perfectly well in VSCode. I installed the server using npm and running the server with the default settings.

[dhruvmanila]

So, I did a bit of experimentation where I forced Neovim to send the formatting request by specifying that the server actually supports it using client.resolved_capabilities.document_formatting = true and the server responded appropriately.

My only question is why is the server specifying documentFormattingProvider: false while it actually can do the formatting?

[evidolob]

That true, we return false there https://github.com/redhat-developer/yaml-language-server/blob/main/src/yamlServerInit.ts#L99 for documentFormattingProvider.
@JPinkney Do you remember why?

[dhruvmanila]

I tracked it down to this PR (#179) which fixes this issue (redhat-developer/vscode-yaml#220) although I'm not sure I understand the reasoning behind this.

[JPinkney]

IIRC it was done that way because VSCode needed formatters to be registered dynamically so that you could dispose of them after they weren't in use. I'm not sure if that's still neccessary though. You might be able to set documentFormattingProvider to true now

[dhruvmanila]

There's already an open PR for this: #316 although it's outdated and needs rebasing.

[dhruvmanila]

For reference, the vscode-json-languageserver provides the initialization option provideFormatter which will then determine whether to provide the formatter on initialization or not.

Source: https://github.com/microsoft/vscode/blob/41c86e5bb8c29f801d6036b738c0c6b548be58e5/extensions/json-language-features/server/src/jsonServer.ts#L140-L141

From the README (server#initialization-options):

provideFormatter: boolean | undefined. If defined, the value defines whether the server provides the documentRangeFormattingProvider capability on initialization. If undefined, the setting json.format.enable is used to determine whether formatting is provided. The formatter will then be registered through dynamic registration. If the client does not support dynamic registration, no formatter will be available.

[ttys3]

I encountered the same problem, the formatter does not work (or can not find a way to enable it)

[lewissetter]

Why was #316 closed? I think #657 is the same problem we're talking about here. From what @dhruvmanila mentioned, it looks like documentFormattingProvider can be set to true since leaving provideFormatter undefined will cause the formatter to be registered dynamically.

[meatballs]

So, I did a bit of experimentation where I forced Neovim to send the formatting request by specifying that the server actually supports it using client.resolved_capabilities.document_formatting = true and the server responded appropriately.

Would you mind sharing how you did that?

[meatballs]

Never mind. I got it working myself by adding a line to my on_attach function:

local on_attach = function(client, bufnr)
  client.resolved_capabilities.document_formatting = true

[dhruvmanila]

I think you should directly use prettier for YAML files as the language server uses that internally.

yaml-language-server/src/languageservice/services/yamlFormatter.ts

Line 47 in f03324a

const formatted = prettier.format(text, prettierOptions);

But, if you want to use the language server, then I suggest to guard the line so that it only affects the YAML language server:

local on_attach = function(client, buffer)
  if client.name == "yamlls" then
    client.resolved_capabilities.document_formatting = true
  end
end

[seanturner026]

I think you should directly use prettier for YAML files as the language server uses that internally.

How would one implement this with neovim?

[dhruvmanila]

How would one implement this with neovim?

Using a formatter plugin like https://github.com/stevearc/conform.nvim. You can find a list here: https://github.com/rockerBOO/awesome-neovim#formatting

[seanturner026]

Awesome! I was able to get it working super easily (the method above in this PR wasn't working).

seanturner026/kickstart.nvim@507223e